Impact Test

Passive means of vibration attenuation have been employed successfully and efficiently in machining systems such as turning and milling. Traditional approach to controlling vibration in a milling system is to develop control mechanisms for cutting tools or machine spindles. However, due to the nature of milling operations where the cutting tools rotate at high speed, the passive vibration control methods

This paper presents the results from experiments and AUTODYN-3D s simulations on the ballistic impact of a KEVLAR s helmet. In the experiment, spherical projectile ($11.9 g), launched from a light gas gun, strikes the helmet with an impact velocity of 205 m/s. The interaction of the projectile with the KEVLAR s helmet is captured using high-speed photography. This helmet-projectile interaction is compared with that obtained from the AUTODYN-3D s simulation. Post-test damage photos from the experiments are also compared with those from the simulations. The response of the helmet from the simulations is consistent with those from the experiments. Also included in this paper are AUTODYN-3D s simulations on two ballistics test standards for KEVLAR s helmets. They are namely the NIJ-STD-0106.01 Type II and the V 50 requirement of the US military specification for Personal Armor System Ground Troops (PASGT) Helmet, MIL-H-44099A. For the simulation on MIL-H-44099A, a fragment-simulating projectile (FSP) strikes the helmet with an impact velocity of 610 m/s. The simulation revealed that an impact velocity above 610 m/s is required to perforate the KEVLAR s helmet. For the simulation on NIJ-STD-0106.01 Type II helmet, the projectile is a 9 mm full-jacketed bullet with a striking velocity of 358 m/s. Results from the simulation show that the KEVLAR s helmet is able to defeat a 9 mm full-jacketed bullet traveling at 358 m/s.

The development of railway wheel steel grades has gone towards higher strength to enhance rolling contact fatigue resistance and ability to withstand thermally induced damage throughout the service lifetime. In this study a recently developed wheel steel material for passenger trains containing high levels of manganese and silicon, approximately 1 wt% of each, was tested in low cycle fatigue at different total strain amplitudes. In addition, monotonic tensile and Charpy V-notch impact testings in the temperature range −60 • C to 180 • C were performed. The results were compared to another steel grade commonly used in Europe for railway wheels. The low cycle fatigue results show similar cyclic lifetime N f , and fatigue stress amplitude development for both materials, but the highly alloyed steel exhibits reduced cyclic softening and hardening during the fatigue life and is in this respect more stable in its behaviour. As is typical for pearlitic-ferritic steels both materials show a pronounced monotonic strain hardening. It was concluded that the increased levels of manganese and silicon have minor effects on monotonic behaviour but substantial influence on cyclic behaviour at ambient temperatures. At increased temperatures, though, there are indications of additional effects on monotonic behaviour. However, the high temperature properties have to be investigated further to gain full understanding of mechanisms and effects.

The split Hopkinson bar is a reliable experimental technique for measuring high strain rate properties of highstrength materials. Attempts to apply the split Hopkinson bar in measurement on more compliant materials, such as plastics, rubbers and foams, suffer from limitations on the maximum achievable strain and from high noise-to-signal ratios. The present work introduces an all-polymeric split Hopkinson bar (APSHB) experiment, which overcomes these limitations. The proposed method uses polymeric pressure bars to achieve a closer impedance match between the pressure bars and the specimen materials, thus providing both a low noiseto-signal ratio data and a longer input pulse for higher maximum strain. The APSHB requires very careful data reduction procedures because of the viscoelastic behavior of the incident and transmitter pressure bars. High-quality stress-strain data for a variety of compliant materials, such as polycarbonate, polyurethane foam and styrofoam, are presented.

Experiments were conducted to study the deformation behaviour of front wheel-tyre assembly of a motorcycle when subjected to frontal impact loading. Impact tests were conducted using an in-house developed pendulum impact test apparatus. Statistical software, Minitab version 13, was employed to support the entire experimental process. Some of the parameters that influence response of the motorcycle in a frontal crash, viz., impact speed, impact mass, inflation pressure level of the tyre, contact geometry of the striker and offset distance of impact location from the axle were varied during the experiments. A 2 5À1 V fractional factorial design was incorporated in the experimental investigation and is described in detail. Experimental results are presented in terms of the maximum residual crush sustained by the wheel, normalized area of deformation and dissipated impact energy. Regression analysis to relate the impact energy to maximum residual crush and normalized area of deformation was then performed. It was found that the deformation of the wheel-tyre assembly is well correlated to the dissipated impact energy. Factorial analysis was also performed to investigate the effect of individual parameters on response of the assembly. These are presented in factorial plots, followed by a brief discussion.

The 3D image correlation technique is used for full field measurement of strain (and strain rate) in compression and tensile split Hopkinson bar experiments using commercial image correlation software and two digital high-speed cameras that provide a synchronized stereo view of the specimen. Using an array of 128×80 (compression tests) and 258×48 (tensile tests) pixels, the cameras record about 110,000 frames per second. A random dot pattern is applied to the surface of the specimens. The image correlation algorithm uses the dot pattern to define a field of overlapping virtual gage boxes, and the 3-D coordinates of the center of each gage box are determined at each frame. The coordinates are then used for calculating the strains throughout the surface of the specimen. The strains determined with the image correlation method are compared with those determined from analyzing the elastic waves in the bars, and with strains measured with strain gages placed on the specimens. The system is used to study the response of OFE C10100 copper. In compression tests, the image correlation shows a nearly uniform deformation which agrees with the average strain that is determined from the waves in the bars and the strains measured with strain gages that are placed directly on the specimen. In tensile tests, the specimen geometry and properties affect the outcome from the experiment. The full field strain measurement provides means for examining the validity and accuracy of the tests. In tests where the deforming section of the specimen is well defined and the deformation is uniform, the strains measured with the image correlation technique agree with the average strain that is determined from the split Hopkinson bar wave records. If significant deformation is taking place outside the gage section, and when necking develops, the strains determined from the waves are not valid, but the image correlation method provides the accurate full field strain history.

In this paper, the composite laminates were fabricated to different weight percentage of uni-directional and stitched cross mat E-glass fibers, glass and Kevlar fiber reinforced with epoxy resins and hardener. For laminates fabrication epoxy matrix is maintained is constant weight percentage (60%) and glass fibers with different stacking sequences is added with various weight percentage. Mechanical behaviour of composites such as tensile property, flexural property & impact resistance are study in this investigation. The various geometry of E-Glass/Kevlar fiber reinforced laminates manufactured by hand lay-up method and followed by compression moulding technique. Where epoxy is constant (60%) and change the fiber percentage, specimens prepared with difference stacking sequences material are tested. The results show tensile strength and impact resistance are high to the stitched cross glass(SCM) fiber mat(40% ) .The flexural strength and natural frequency is high in order to Chopped strand (CSM) mat(10%)/Kevlar(K) fiber(30%), CSM(30%)/K(10%). (Impact Factor: 0.997) 37 addition of 10 wt% short Kevlar fibers into glass fiber composite was shown to be the advisable reinforcement content to achieve better impact strengths. [22] M.T.Isa et al (2013) Effect of fiber type and combinations on the mechanical, physical and thermal stability of polyester hybrid composites. Composites: Part B 52 (2013) 217-223 [23] A.

In this work, 316L stainless steel (SS) powder was used. The composition of the powder is as follows: 0.015% C, 1.75% Mn, 0.45% Si, 17.24% Cr, 2.79% Mo, 14.65% Ni, and balance iron. Mixed powder was compressed cold using single action press under 800 MPa pressure. Compressed samples were sintered at 1200°C, 1250°C, and 1300°C into the nitrogen gas atmosphere. In order to determine the mechanical properties of the produced specimens, the fatigue tests, tensile test, three-point bending test, impact test and hardness tests were applied to the specimens. Determined mechanical properties in the result of this work were compared to the properties as stated in ASTM F138-G2. Besides that to define the microstructures of the produced specimens in detail, metallographic studies were performed.

Passive means of vibration attenuation have been employed successfully and efficiently in machining systems such as turning and milling. Traditional approach to controlling vibration in a milling system is to develop control mechanisms for cutting tools or machine spindles. However, due to the nature of milling operations where the cutting tools rotate at high speed, the passive vibration control methods find very limited application with the traditional approach. In order to utilise the potential of the passive vibration control methodology in milling applications, the milling operation should be viewed as a system comprising an elastic structure and operation parameters. Dynamics of this closed-loop system should improve with improvement in dynamics of any of the system components, especially within the elastic structure that comprises the cutting tool, the machine tool, the workholding system and the workpiece. Although the level of improvement will vary depending on which component of the elastic chain is targeted for this purpose. This paper presents the development and testing of tuned viscoelastic dampers (TVDs) for vibration control through their application on a workpiece in milling operations. This work targets workpiece held on a palletised workholding system for the control of unwanted vibration and thus deviates from the traditional approach where cutting tool and/or machine spindles are targeted for vibration control strategies. Palletised workholding systems, due to their compact design, offer an opportunity to design passive damping mechanisms that are easier to implement in the case of a milling system. The TVD developed through this research is based on a commercially available viscoelastic damping polymer. Advantage of such materials is their high damping performance over a wide range of excitation frequencies. The TVD design process has used a unique combination of analytical modelling with experimental FRF data. Modal impact testing showed that the application of the TVD reduced the amplitude of vibration acceleration by 20 dB for the target mode. Since the target mode corresponded to torsional vibration, the TVD was effective in two planar coordinates, i.e. X and Y. In addition, the TVD also significantly reduced the amplitude of a vibration mode far from the mode it was designed for. The system has been tested experimentally to demonstrate significant reduction in vibration amplitudes during a milling process. The milling tests with different combinations of cutting parameters show that multi-TVD approach is always valid regardless of the parameters being used. The only requirement for TVDs to function effectively is that the natural frequency of the system, for which the TVDs are designed, is excited during the milling process. r

Mild steel and stainless steels are the two utmost steels used in the automotive industries as well as in various constructional and industrial applications. Welding of these steels with lesser defects and higher strengths is the most important need of the current industries. In this paper, TIG and MIG welding is preformed between two dissimilar steels. Transitional changes happen frequently in physical and microstructural properties; therefore, this study carries out an experimental and microstructural analysis to determine the properties like hardness, impact strength, tensile strength and microstructure of the weld zone.

Increasing competition and innovation in automobile sector tends to modify the existing products by new and advanced products. Today composite materials have changed all the material engineering. The evolution of composite materials has given an opportunity to various designers to use new and better materials resulting in cost reduction, increase in efficiency and better utilization of available resource. Most of the industries are using composite materials such as Epoxy resin, glass fiber and epoxy carbon. In this paper, the objective is to manufacture the composite lever clutch to replace the conventional aluminium lever clutch. The composite lever clutch will be compared the results with conventional lever clutch under different mechanical testing with evaluating of different mechanical properties such as tensile strength, bending strength, impact strength, fatigue strength by using appropriate experimental technique.

A flip chip package was assembled by using 6-layer laminated polyimide coreless substrate, eutectic Sn37Pb solder bump, two kinds of underfill materials and Sn 3.0 Ag 0.5 Cu solder balls. Regarding to the yield, the peripheral solder joints were often found not to connect with the substrate due to the warpage at high temperature, modification of reflow profile was benefit to improve this issue. All the samples passed the moisture sensitive level test with a peak temperature of 260°C and no delamination at the interface of underfill and substrate was found. In order to know the reliability of coreless flip chip package, five test items including temperature cycle test (TCT), thermal shock test (TST), highly accelerated stress test (HAST), high temperature storage test (HTST) and thermal humidity storage test (THST) were done. Both of the two underfill materials could make the samples pass the HTST and THST, however, in the case of TCT, TST and HAST, the reliability of coreless flip chip package was dominated by underfill material. A higher Young's modules of underfill, the more die crack failures were found. Choosing a correct underfill material was the key factor for volume production of coreless flip chip package.

Prestressed concrete sleepers (or railroad ties) are among the major and the most common structural components of railway track structures. Their main duty is to carry and transfer the wheel loads from the rails to the ground. In general, railway tracks suffer with the extreme loading conditions, which are attributable to the train operations with either wheel or rail abnormalities such as flat wheels, dipped rails, etc. These loads are of very high magnitude but short duration, as well as they are of low-possibility occurrence during the design life of the prestressed concrete sleepers. In spite of the most common use of the prestressed concrete sleepers in railway tracks, their impact responses and behaviours are not deeply appreciated nor taken into the design consideration. This experimental investigation was aimed at understanding the progressive dynamic behaviours of prestressed concrete sleepers in railway track structures under repeated impact loading, in order to form the state of the art of limit states design concept for prestressed concrete sleepers. A high-capacity drop weight impact testing machine was constructed at the University of Wollongong as to achieve the purpose. Series of repeated impact tests for the insitu prestressed concrete sleepers were carried out, ranging from a low drop height to the ultimate drop height where the ultimate failure occurred. The accumulative impact damage and crack propagation are highlighted in this paper. The effects of track environment including soft and hard tracks together with the relationship between the resultant bending moment of prestressed concrete sleepers and the applied impact force as a design guideline were also presented.

This paper presents the failure analysis of AISI-304 stainless steel tank that was fabricated by welding and used for the storage of styrene monomers. After about 13 years of satisfactory operation, significant cracking was observed adjacent to the weld joints and in base plate near tank foundation. Weld repair was by shielded gas arc welding using AISI 308 stainless steel filler

Natural fibers have the advantage that they are renewable resources and bio- degradable. These agricultural wastes can be used to prepare fiber reinforced polymer composites for commercial use. Application of composite materials to structures has presented the need for the engineering analysis the present work focuses on the fabrication of polymer matrix sandwich composites by using natural fibers kenaf and jute which are abundant nature in desired shape by the help of various structures of patterns. Here E-glass fibers are used to improve strength. This sandwich composite are Fabricated by simple Hand layup technique. In this composite produce more tensile strength than other composite materials like as banana, sisal, coir, etc.,, The mechanical properties (flexural strength, Tensile strength, impact, and compression) are determined by flexural test, tensile test, impact test, density test, and their results are measured on sections of the material and make use of the natural fiber reinforced polymer sandwich composite material for automotive seat shell manufacturing, marine like boat, ships panels and aero vehicles parts.

A detailed description of the instrumented dropweight impact machine is presented. The instrumentation, the calibration, the inertial loading correction, and the dynamic analysis of a concrete beam specimen undergoing three-point impact flexural loading are described. Some results, using such an impact testing machine, obtained from tests done on plain concrete, fiber-reinforced concrete, and conventionally reinforced concrete are presented. It is concluded that the use of such a testing machine may be successfully made in order to test cementitious materials under)mpact.

Nanocomposites based on low-density polyethylene (LDPE), containing 0.5, 1, 2, 3, and 5 wt of nanoalumina, were prepared by melt-mixing at 125°C and hot melt-pressing to thin polymer film at 125°C. To enhance the interfacial interaction between alumina and LDPE, alumina surface was treated with silane which acts as coupling agent. The effects of alumina additions to the structure and morphology of LDPE matrix were characterized using Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM), respectively. The mechanical behaviour of nanoalumina-reinforced LDPE composite was studied using tensile tests, flexural tests, and impact tests. The interfacial adhesion between nano alumina particle and LDPE matrix was investigated. The result showed that the reinforcement performance of nano alumina to LDPE matrix was attributed to the interfacial adhesion between nanoparticle and polymer matrix. The addition of 1 wt nano alumina has successfully enhanced the mechanical properties of LDPE material. © 2012 Ching Yern Chee et al.

http://dl.acm.org/citation.cfm?id=2490013

In order to establish a rational verification method for each limit state (mainly the serviceability and ultimate limit states) in the case of impact-resistant reinforced concrete structures, an experimentallybased study using not only small-scale but also prototype models should be conducted. However, it is not easy or economical to conduct prototype experiments. If a satisfactory numerical analysis method could be established then it would be easier to perform than experiments, due to the advances in computer technology. However, it is not easy to numerically analyze prototype structures under impact loading by means of 3D elasto-plastic finite element (FE) analysis method because very large matrices must be handled. Here, in order to establish a modified method for the tensile strength of the concrete so as to be able to satisfactorily perform the analysis using a coarse mesh, an equivalent tensile fracture energy concept for the concrete elements is proposed and its applicability is investigated by comparing with the experimental results. From this study, it is shown that even though a coarse mesh is used for the prototype reinforced concrete girder, similar results to those using a fine mesh can be obtained and these results are in good agreement with the experimental ones.

An investigation of the low velocity impact load level at which a composite laminate will delaminate is presented. The delamination threshold load is described as the load level, obtained from the load-time history or load-displacement plot, at which a sudden load drop occurs due to specimen stiffness loss as a result of laminate level damage. Approximately 500 low velocity impact load-time histories from the Air Force Research Laboratory (AFRL) Low Velocity Impact Database are used to investigate the delamination threshold load. The database contains laminate impact test data for graphite/epoxy (AS4/3501-6), graphite/PEEK (AS4/APC-2), and graphite/BMI (IM7/5260) material systems. The delamination threshold load observations are compared to C-scan damage measurements of impacted specimens to determine if the sudden load drop corresponds to delamination development. Published by Elsevier Science Ltd.

This paper concerns the protective structures against rock fall. We propose a new concept of rock-shed protection. The proposed rock-shed protection is made of reinforced concrete slabs held up by specially designed supports that act as a type of expendable fuse to absorb high rock-fall energy especially when shock occurs on the side of the slab. Thus, by a simple change of damaged supports and local restoration of concrete in the impact area, the structure can continue to be used. We present also an experimental method to characterize and analyze shock absorption effected by this type of reinforced concrete slab. The analyzed slab is a 1/3 scale reproduction of an actual structure. r

Large scale heterogeneity is a major problem when shock properties of concrete materials shall be derived efficiently. A mesomechanical method proposed earlier [Riedel W. Beton unter dynamischen Lasten: Meso-und makromechanische Modelle und ihre Parameter, Ed.: Fraunhofer-Institut fu¨r Kurzzeitdynamik, Ernst-Mach-Institut EMI. Freiburg/Brsg.: Fraunhofer IRB Verlag; 2004. p. 117-43. ISBN: 3-8167-6340-5 /http://www.irbdirekt.de/irbbuch/S; Thoma K, Riedel W, Hiermaier S. Mesomechanical modeling of concrete shock response, experiments and linking to macromechanics by numerical analysis. In: Proceedings of European conference on computational mechanics, Mu¨nchen, Germany, September 1999 (CD-ROM).], combining plate impact experiments on the constituents 'cement' and 'aggregate' together with simulations of the concrete mesostructure, is extended in this work. Hereby, the parameters describing macroscopic stress wave propagation are analysed in direct simulations of the discontinuous composite of aggregate, mortar and pores. This allows the replacement of an important number of experiments on large samples with inevitable scattering by a reduced set of smaller standard tests together with simulations. The basics and the validation of this methodology are demonstrated in the acoustic regime and compared to available shock experiments for a wide pressure range. The present paper describes the enlargement of the pressure range for the derived equation of state properties. Therefore, the concrete mortar has been impact tested in shock reverberation configuration leading to reflected pressures up to 18 GPa. The shock and equation of state properties are derived for two 35 MPa conventional strength mixtures and a 135 MPa high strength concrete. The results are compared to available literature sources. r

The importance of materials in modern world can be realized from the fact that much of the research is being done to apply new materials to different components. The evolution of composite materials has given an opportunity to various designers to use new and better materials resulting in cost reduction and increase in efficiency. This paper presents development and manufacturing of two wheeler lever clutch by using epoxy resin and glass fiber composite material. In this paper, the aim is to manufacture the composite two wheeler lever clutch and compare the results with conventional aluminium lever clutch under different mechanical testing with evaluating of different mechanical properties such as tensile strength, bending strength, impact strength, fatigue strength by using appropriate experimental technique.

During automotive related accidents, PVB plays an important role in both pedestrian and passenger protection as an interlayer of automotive windshield. In this paper, dynamic constitutive behavior of PVB material is thoroughly studied. Firstly, a set of dynamic compression impact experiments on PVB specimens using SHPB (Split Hopkinson Pressure Bar) method are conducted at strain rates from 700/s to 4500/s. Details of the constitutive response is analyzed based on the validation of experiment data. Stress-strain curve of PVB is then divided into two parts, i.e., "Compaction Stage" and "Hardening Stage". Dislocations and entanglements among molecules are major reasons for the two-stage phenomena. Constitutive behaviors are different in low and high speed impacts, leading to three times more energy absorption ability of PVB in high speed impact scenario. Further, data fitting models based on both MooneyeRivlin and Ogden Model are studied and then compared. MooneyeRivlin Model is found to be more appropriate to describe PVB material. Moreover, PVB is proved to be a rate-dependent material with the failure strength intensify factor b z 4. PVB material shows little viscoelasticity after comparison of the both models with and without the viscoelasticity part. Results offer critical experimental data, constitutive models and analysis of PVB material to further study of automotive crashworthiness and pedestrian/passenger protection.

In ballasted railway tracks, one of the important components that supports the rails and distributes wheel/rail loading onto the ballast supporting formation is a railway sleeper (sometimes is also called a Brailway tie^). This paper presents results of an experimental modal analysis of prestressed concrete sleepers in both free-free and in-situ conditions, incorporating the dynamic influence of sleeper/ballast interaction. Dynamic interaction between concrete sleepers and ballast support is crucial for the development of a dynamic model of railway track capable of predicting its responses to impact loads due to wheel flats, wheel burns, irregularities of the rail, etc. In this study, four types of prestressed concrete sleepers were in-kind provided by the Australian manufacturers. The concrete sleepers were tested using an impact hammer excitation technique over the frequency range of interest, 0-1600 Hz. Frequency response functions (FRFs) were measured using PULSE modal testing system. The FRFs were processed using STAR modal analysis package to identify natural frequencies and the corresponding mode shapes for the sleepers. The conclusions are presented about the effect of the sleeper/ballast interaction on the dynamic properties of prestressed concrete sleepers and their use for predicting railway track dynamic responses.

Quasisteady modeling of linear stroke flow mode magnetorheological (MR) (or electrorheological (ER)) dampers has focused primarily on the utilization of the Binghamplastic constitutive model to assess performance metrics such as damping capacity. In such Bingham-plastic MR (or ER) flows, the variable yield stress of the fluid, y , is activated by applying magnetic (or electric) field. The Bingham-plastic model assumes that the material is in either (1) a pre-yield condition where the local shear stress is less than the yield stress, 5 y , or (2) a post-yield condition, where the local shear stress is greater than the yield stress, > y , so that the material flows with a constant post-yield viscosity. The objective of this study is to analyze the damping capacity of such a controllable MR or ER damper in the situation when the field dependent fluid exhibits post-yield shear thinning or thickening behavior, that is, the postyield viscosity is a function of shear rate. A Herschel-Bulkley model with a field dependent yield stress is proposed, and the impact of shear rate dependent viscosity on damping capacity is assessed. Key analysis results -velocity profile, pre-yield thickness, and damping coefficient -are presented in a nondimensional formulation that is consistent with prior results for the Binghamplastic analysis. The nondimensional analysis formulated here clearly establishes the Bingham number as the independent variable for assessing flow mode damper performance.

a b s t r a c t PVD coatings are of great interest due to their high hardness, wear and oxidation resistance, thermal stability and lubricity. Gradient deposition technology allows improving adhesion to substrate and mechanical properties of the coating-substrate system by elimination of the mismatch in materials properties at the interface and reduction of residual stresses. The present study aims at the assessment of performance of the nano-composite gradient superhard AlTiN/Si 3 N 4 and also TiN, TiCN, TiAlN, AlTiN gradient PVD coatings deposited onto cemented carbide substrate. Erosive, abrasive and impact wear tests were conducted to obtain the insight into qualitative and quantitative aspects of PVD coatings resistance to wear. Microstructural analysis has indicated that gradient deposition technology allows reducing the risk of coatings decohesion due to weak adherence. The fracture of AlTiN/Si 3 N 4 and other coating systems investigated under all conditions is initiated at the defect areas (such as pores and protuberances). The performance of nano-composite gradient superhard AlTiN/Si 3 N 4 coating is superior under abrasive wear; very good under erosive wear; and quite good under impact wear.

Work has been carried out to develop a fast test method for the determining of railhead traction levels. Current methods used in the field are time consuming and offer relatively little control of external or test parameters. A pendulum rig has been used for this investigation and adapted to measure railhead friction levels under various states of contamination. The rig consists of an aluminium tubular pendulum; on the end of which is a spring mounted, rubber pad (slider pad). The rig functions on the same principles as used in a Charpy impact test, i.e. energy is lost as the slider pad comes into contact with a surface (in this case the rail head). This loss in kinetic energy is measured and can be translated into a friction coefficient.

Long-span guardrail systems have been recognized as an effective means of shielding low-fill culverts. These designs are popular because, in comparison with other systems that attach posts to the top of the culvert, they are able to shield the culvert safely while creating little additional construction effort and limiting the damage to the culvert and the need for repair. However, previous long-span designs were limited by the need to use long sections of nested guardrail to prevent rail rupture and by the need for large lateral offsets between the barrier and the culvert. The Midwest Guardrail System (MGS) long-span design eliminates those two shortcomings by applying the benefits of the MGS to a long-span design. The MGS long-span design increased vehicle capture and stability because of the increased rail height, limited the potential for pocketing and wheel snag through the use of controlled-release terminal posts adjacent to the unsupported span, and greatly increased the tens...

Recycled Concrete aggregates (RCA) are comprised of crushed, graded inorganic particles processed from the materials are used in the constructions industry. The aim of this project is to determine the strength characteristics of recycled aggregates for application of structural concrete in high strength, which will give a better understanding on the properties of concrete with RAC, as an alternative material to coarse aggregate (NA) in structural concrete. The scope is this project is to determine and compare the strength of concrete by using different percentage of recycled concrete aggregates. Recycled aggregate is also the type of artificial aggregate which is obtained from (C&D) wastes i.e. Construction and demolition. Constructions and demolitions are processes that go hand in hand. In India the demolished building rubble generally goes to waste materials in landfills. Recycling of these concrete waste materials from demolition building can provide a solution to this problem. The investigation was carried out using Specific gravity test, sieve analysis test, Impact test, Water absorption test, Crushing value test, Workability test and compressive strength test. There are total six batches of concrete mixes, consisting of every 20% increment of recycled aggregate replacement, from 0% to 100%.

Recent research programs conducted on low-velocity impact events on composite structures have used force as the sole governing parameter and based their damage resistance and tolerance considerations on the peak recorded value. Understanding of other available parameters, such as contact duration and coefficient of restitution, which are related to the effective structural stiffness of the target, is fundamental in the design of a methodology for assessing impact performance and can offer greater insight in the interpretation of future research programs. An experimental database is gathered through drop tower impact testing by means of a rigid striker on clamped circular plates, for a particular polymer composite system. Several researchers have presented data showing that a critical value of the impact force for the onset of damage exists. Structural properties are hereby studied in both the sub-and supercritical regimes, which means for impact energy values below and above the damage threshold. A modified approach to the classic spring-mass model, which employs the notions of damaged stiffness and dissipated energy, leads to the derivation of approximate formulas that describe the peak force-energy curve. In particular, the introduction of a dashpot to simulate the effect of damage greatly improves the accuracy of the model in the regime beyond the structural integrity threshold. A novel method to assess the residual performance of the damaged plate is developed, and it consists in low-energy, nondestructive impact testing, the results from which bear a striking resemblance with the curves obtained by compression after impact.

Bead-on-plate submerged arc welding was conducted on St37 steel by manufactured Cr, Mo, and Cr-Mo active basic fluxes produced via the unfused bonded method. The base metal heat-affected zone and weld metal (WM) microstructures were identified and characterized by optical microscopy and scanning electron microscopy. Furthermore, each element's recovery rate (η) and slag factor (α) determine the amount of element transferred from flux into WM. Then, the ferrite morphologies volume fraction of WMs was measured. Moreover, the chemical analysis of slag and inclusions was evaluated by point scan energy-dispersive X-ray spectroscopy and extensively discussed. The number density and size of the inclusions as well as their effects on the acicular ferrite (AF) formation were also elaborated. Then, the WMs' longitudinal tensile strength and Vickers hardness (HV) were measured. Finally, the Charpy V-notch test was conducted to determine the impact toughness; the fracture surfaces were investigated, as well.

This work presents an experimental characterization of the mechanical behaviour of the EK4 deep drawing steel. The experimental procedure encompasses spectrometry, metalography, tension testing and hardness measurements. Special attention is devoted to the derivation of the elastic and plastic parameters involved in the assumed constitutive model based on the anisotropic Hill-48 yield criterion. The simulation of the deformation process during the whole tensile test is subsequently performed with the aim of assessing the adequateness of the proposed methodology. It should be mentioned that the material parameters obtained with this procedure are the basic data for the modelling and experimental validation of different deep drawing applications presented in Part II of this work.

Brittle spheres are crushed and fragmented between two rigid platens dynamically. More than 140 plaster spheres with two different strengths (37 and 59 MPa) and three different sizes (50, 60 and 75 mm) were tested. The impact energies varied from 10 J to over 300 J with impact velocities ranging from 1 to 9 m/s. Twelve different failure patterns are identified, depending on the number of fragments and severity of crushing around the axis of compression. In general, fragments resulted from the double dynamic impact are of two different sizes, namely larger fragments resulted from primary fractures (mainly passing through a diameter of the sphere) and smaller fragments resulted from secondary fractures (do not pass through a diameter of the sphere). The number of smaller fragments increases with the impact energy. The cumulative mass of all fragments of size larger than d [i.e. R(d)] can be fitted into a power law of d (or the so-called Gates-Gaudin-Schuhmann distribution), but there are two distinct slopes of the double-log scale plot of R(d) versus d. The power index n of the larger-fragment-fit is, in general, larger than that of the smaller-fragment-fit. Typically, n ranges from 0.8 to 1.6 and decreases with the impact energy and strength of the sphere. The diameter of the end crushing zone is found approximately proportional to m 1/4 r 1/4 v 1/2 , where m is the mass of the impactor, r is the radius of the sphere and v is the impact velocity. In addition, taking into account of kinetic energy loss, crushing modulus as well as specific fracture energy were obtained for the spheres. D

The 2000-kg pickup truck is a very important vehicle in roadside safety research since it is specified in many of the tests in NCHRP Report 350.(1) The characteristics of the pickup truck make it a very demanding crash test vehicle. Because the 2000-kg pickup truck is an important crash test vehicle it was the very first vehicle chosen for development of a finite element model. The nonlinear finite element program LS-DYNA has become an important feature of roadside hardware design and analysis in recent years and much of the success of these modeling efforts is partly due to the availability of a good 2000-kg pickup truck model. Like all models, the model has evolved over the past decade. New features and improvements have been added continuously to the model by many different teams in order to solve specific analysis problems. One particular area where there has been a great deal of activity is in the area of modeling the suspension properties of the vehicle. Suspension response is particularly important for 2000-kg pickup truck impacts because the vehicle often experiences stability problems in impacts with roadside hardware. This paper summarizes a number of improvements and modifications to version 9 of the NCAC 2000-kg pickup truck model. These improvements involved changes to the finite element model, changing element properties and obtaining suspension response properties from physical tests. The 2000-kg truck model is then validated against a series of low-speed live-drive tests with an instrumented pickup truck. The improved model provides more realistic vehicle suspension response than earlier models and should prove a valuable addition to future finite element modeling activities.

The potential to increase suggested flare rates for strong post, W-beam guardrail systems and thus reduce guardrail installation lengths is investigated. This reduction in length would result in decreased guardrail construction and maintenance costs, and reduce impact frequency. If the W-beam guardrail can withstand the higher impact angles, with only modest increases in accident severity, total accident costs can be reduced. Computer simulation and five full-scale crash tests were completed to evaluate increased flare rates up to, and including, 5:1. Computer simulations indicated that conventional G4(1S) guardrail modified to incorporate a routed wood block could not successfully meet NCHRP Report 350 crash test criteria when installed at any steeper flare rates than the 15:1 recommended in the Roadside Design Guide. However, computer modeling and full-scale crash testing showed that the Midwest Guardrail System (MGS) could meet NCHRP Report 350 impact criteria when installed at a 5:1 flare rate. Impact severities during testing were found to be greater than intended, yet the MGS passed all NCHRP 350 requirements. Hence, flaring the MGS guardrail as much as 5:1 will still provide acceptable safety performance for the full range of passenger vehicles. Increasing guardrail flare rates will reduce the overall number of guardrail crashes without significantly increasing risks of injury or fatality during the remaining crashes. Therefore, it is recommended that, whenever roadside topography permits, flare rates should be increased to as high as 5:1 when using the MGS.

Experimental test methods for the evaluation of the resistance of heels of ladies' shoes in impact and impact fatigue loading are well-defined by ISO standard procedures that indicate all the conditions of experiment. A first Standard specifies the test method for determining the impact strength of the heels [1]. The result provides an assessment of the liability to failure under the occasional heavy blows. A second Standard [2] specifies a test method for determining the ability of heels of ladies' shoes to withstand the repeated small impacts provoked by normal walking. These Standards strictly define the features for two different devices (with specific materials, geometries, weights, etc.) and all the experimental procedures to be followed during the tests. This paper describes the technical solutions used to design one single experimental machine able to perform impact testing of heels in both conditions. Joining the accuracy of mechanic movements with the speed of an electronic control system, a new and versatile equipment for the complete experimental characterization of heels was developed.

A new plate impact experiment is presented for studying dynamic fracture processes that occur under sub-microsecond loading. The experiment is designed to provide comparatively straightforward interpretation within the framework of fracture mechanics. A disc containing a mid-plane, pre-fatigued, edge crack that has been propagated halfway across the diameter is impacted by a thin flyer plate of the same material. A

In the present study plate-impact pressureshear experiments have been conducted to study the dynamic shearing resistance of molten metal films at shearing rates of approximately 107s -1 . These molten films are generated by pressure-shear impact of relatively low melt-point metals such as 7075-T6 AI alloy with high hardness and high flow-strength tool-steel plates. By employing high impact speeds and relatively smooth impacting surfaces, normal interfacial pressures ranging from 1-3 GPa and slip speeds of over 100 m/s are generated during the pressure-shear loading. The resulting friction stress (~100 to 400 MPa) combined with the high slip speeds generate conditions conducive to interfacial temperatures approaching the fully melt temperature regime of the lower melt-point metal (7075-T6 aluminum alloy) comprising the tribo-pair.

This paper presents first material tests on HDPE and PVC, and subsequently impact tests on plates made of the same materials. Finally, numerical simulations of the plate impact tests are compared with the experimental results. A rather comprehensive series of mechanical material tests were performed to disclose the behaviour of PVC and HDPE in tension and compression. Quasi-static tests were carried out at three rates in compression and two in tension. Digital image correlation, DIC, was used to measure the in-plane strains, revealing true stress-strain curves and allowing to analyze strain-rate sensitivity and isotropy of Poisson's ratio. In addition, dynamic compression tests were carried out in a split-Hopkinson pressure bar. Quasi-static and dynamic tests were also performed on clamped plates made of the same PVC and HDPE materials, using an optical technique to measure the full-field out-of-plane deformations. These tests, together with the material data, were used for comparative purposes of a finite element analysis. A reasonable agreement between experimental and numerical results was achieved.

Structural failure of post-and-beam w-beam guardrails during impact is sometimes due to the rupture of the w-beam rail where two sections are spliced together with bolts. This paper summarizes a study of the mechanics of failure of the splice connection. The causes of rupture are identified and a design alternative is formulated that will reduce the likelihood of rupture of the splice connection. The tensile forces in the w-beam rail and the mode of deformation of the splice connection during impact were critical factors considered in the study. The results of full-scale crash tests, laboratory tests and finite element analysis indicate that relocating splices to mid-span locations would greatly reduce the chance of observing a rupture of the guardrail in full-scale crash tests as well as real-world collisions.

In this study, sandwich panels were fabricated with neat and nanophased foam cores and 3-layered plain weave carbon fabric/SC-15 epoxy-nanoclay composite face sheets. Neat and nanophased foam cores with Nanocor Ò I-28E nanoclay at a loading of 0.5% and 1% by weight were prepared. Sandwich panels were then fabricated using co-injection resin transfer molding process. The facesheets were made by infusing SC-15 epoxy containing 1% and 2% by weight of nanoclay into 3 layers of plain weave carbon fabric. Samples of size 100 • 100 mm were then cut from the panels and subjected to low-velocity impact loading using an instrumented impact test setup. Impact response of the samples was recorded and compared. The tested samples were then sectioned into two halves and scanned using a scanner, optical and scanning electron microscopes to understand the failure patterns. Samples with nanophased foam sustained higher loads and had lower damage areas as compared with neat counterparts. Nanophased foam cores exhibited brittle fracture.

Roll Over Protective Structures (ROPS) are safety devices fitted to heavy vehicles to provide protection to the operator during an accidental roll over. At present, ROPS design standards require full scale destructive testing which can be expensive, time consuming and unsuitable for small companies. More economical analytical methods are not permitted due to a lack of understanding on post yield behaviour and energy absorption capacity of ROPS. With this in mind, a research project was carried out to comprehensively investigate ROPS behaviour using analytical techniques supported by experiments. This paper presents the dynamic impact analysis of a bulldozer ROPS using calibrated finite element models. Results indicate that (i) ROPS posts have significant influence on the energy absorbing capacity,(ii) dynamic amplifications in energy could be up to 25% and (iii) stiffer ROPS cause high peak decelerations that may be detrimental to the operator. The feasibility of using analytical techniques for evaluating ROPS performance has also been demonstrated.