Ls-Dyna

A great number of masonry arch bridges are still in service in Europe, the Middle East, and other parts of the world. Assessing the capacity of these historical structures is an important problem both for safety and preservation purposes. This paper addresses the assessment of the Titus Tunnel Bridge, a single-span, Roman stone arch pedestrian bridge (Common Era 70) located in Antakya, Turkey, using analytical and numerical techniques. The bridge is located in an active seismic zone and has survived several major earthquakes. Therefore, it is important to understand the Bridge's subtle features that have helped the structure survive for the last two millennia. Furthermore, being a single-span semicircular stone arch, the bridge exemplifies the main construction blocks of several masonry bridges around the world. First, the analytical techniques, i.e., Heyman's geometrical factor of safety and the mechanism method, are used to assess the capacity of the bridge under simple loading conditions and to validate the finite-element (FE) models. Then, discrete FE modeling with explicit time integration is used to investigate the arch behavior under both gravity and earthquake loading conditions. It is observed that the Titus Tunnel Bridge has a significant margin of safety against collapse, which also explains the approximately 2,000-year lifetime of the structure. The results are also used to provide estimates on the maximum expected ground motions in the region using a precarious rocks analogy.

Birdstrike on aircraft is a major threat to human life and there is a need to develop structures which have high resistance towards birdstrike. This paper describes the numerical simulation of bird strike on the Aluminium Silicon Carbide (Al-SiC) metal matrix composite wing leading edge using LS-Dyna software. The metal matrix composite chosen has the composition of Aluminium 85% and Silicon Carbide 15%. At this composition the impact force of the material is high which means the material is more resistant to impacts which is suitable for the wing leading edge as it is subjected to events like birdstrike. For this simulation we have chosen the wing structure of Boeing 737 aircraft. The wing leading-edge section was designed using CATIA V5 with skin thickness of 2mm. Also, the ribs and the spar were designed for better results. A hemisphere cylindrical bird model is used for bird strike and is designed in LS Pre-Post V4.7.7 with length 196mm and diameter 98mm. The wing leading edge model was imported to the LS Pre-Post and was aligned properly for birdstrike analysis. The analysis of the birdstrike is carried out using the Lagrangian method. The required keyword input data such as Boundary Definition, Control, Contact Definition, Material properties for the bird and the wing leading edge section and Velocity for the bird are defined as per the requirements of the analysis. The simulation was run at different velocities ranging from 50-150m/s. The results were obtained graphically as Pressure vs. Time, Effective Stress vs. Time, Effective Plastic Strain vs. Time, Rigid Body Displacement vs. Time, Internal Energy vs. Time and Kinetic Energy vs. Time graphs. Using these graphs, the graphs for the Effective Stress vs. Effective Plastic Strain & Rigid Body Displacement vs. Velocity were plotted. In this analysis, it was observed that the Effective Stress of the wing leading edge with Al-SiC material has been increased by approximately 100 MPa with respect to the traditional Al 7075 T6 material. Also, the pressure distribution over the wing leading edge surface is smoother during impact for wing section with Al-SiC material. The energy absorption of the wing section has been increased. The overall strength of the wing leading edge section with Al-SiC as the material has been increased when compared to the wing leading edge section with Al 7075 T6 material.

There is an ever-increasing demand for more advanced and user-friendly FEM packages. Despite the great progress achieved in FEM industry, the modelling of masonry structures is still challenging at several scales. The present paper discusses the potential capabilities of both FEM packages ANSYS and LS-DYNA for multiple scales modelling of masonry structures. The smeared and discrete modelling approaches, constitutive models and solution strategies will be discussed and the outcome will be supported with examples for unreinforced and reinforced masonry. Further discussion will be given to the difficulties and challenging problems. The paper will be concluded to recommendations to enhance the current state and the aspects of future works.

In recent years, concerns about the sustainability and social responsibility (CSR) of businesses have become an increasingly high profile issue in many countries and industries, none more so than the mining industry. For mining, one outcome of the CSR agenda is the increasing need for individual companies to justify their existence and document their performance through the disclosure of social and environmental information. This paper explores recent trends in the reporting of such impacts and issues in the global mining industry. It offers a detailed review of the development of the media of social and environmental disclosure in the mining industry, and of the factors that drive the development of such disclosure. A temporal analysis of the recent trends in disclosure using a case study of the world's 10 largest mining companies is presented. Whilst there is evidence of increasing sophistication in the development of social and environmental disclosure, there is considerable variation in the maturity of reporting content and styles of these companies. The paper offers a simple classification of reporting companies, from 'leaders' to 'laggards'. Stronger leadership and co-operation from the top reporting companies is necessary to support the laggards of the industry.

Centre and the Cranfield Impact Centre (CIC) inside Cranfield University. Carbon Fibre Reinforced Plastic (CFRP) tube is an important material for the lightweight design of automotive and aerospace structures. Simulation methods of Aluminium and CFRP thinwalled tubes subjected to axial compression and filled with Aluminium foam was investigated in this thesis project. For the Aluminium tube and Aluminium foam, *MAT_3 and *MAT_63 were employed respectively to execute the simulations of the empty and filled tube. To obtain the ideal element size for the mesh, a theoretical method was used to correlate the results with the numerical values obtained in LS-DYNA software. For the CFRP tube, the Finite Element (FE) model was built based on the twolayer shell model, using the *MAT_54/55 material formulation, failure strategy and the parameters sensitivity of the model. Then the simulation model was verified by using duplicate specimens comprised of carbon fibre/epoxy unidirectional prepreg tape. Furthermore, the modelling method of crush trigger B45 and different types of loading speed (static and dynamic) were analysed. A correlation was made between the physical testing results and the numerical values obtained from LS-DYNA to define the ideal values for the strength parameters.

A welding procedure (WPS) for MIL A46100 steel armor joints using the gas metal arc welding process (GMAW) was developed and qualified according to mechanical and non-destructive (NDT) requirements of military codes. Obtained results were compared to shielded metal arc welding (SMAW) procedures used to weld this type of steel. It was found that designed WPS is a suitable option to weld MIL A46100 armors according to the results obtained. In addition, a narrower heat affected zone (HAZ) was obtained with designed WPS which should lead to a better in-service armor performance according to results of previous studies. Finally, an increase in Charpy v-notch (CVN) test impact energy compared to the SMAW procedure was found.

This paper discusses the different features of ANSYS and LS-DYNA in solving structural analysis using finite element approach. ANSYS and LS-DYNA are two popular engineering software tools that are used for finite element analysis. The difference between ANSYS and LS-DYNA lies in different solution procedures and time integration methods they use. ANSYS is an implicit analysis program while LS-DYNA is an explicit analysis program. This paper compares the general properties of the two programs through an impact problem and explains the reason. A simple two degrees of freedom system is solved to show how the implicit and explicit methods are implemented. Conclusively, advantages and limitations of both programs are discussed as well as their applicable areas.

Este artículo revisa los materiales compuestos de matriz metálica (CCM) usados en las industrias eléctrica y electrónica. Usualmente, los composites útiles en estos sectores corresponden a la familia de las aleaciones ligeras, reforzadas con fibras o partículas. Por tal motivo, la revisión está enfocada en las aleaciones Al, Ti y Mg, sus propiedades y aplicaciones.

Las chumaceras y los ejes de molino de caña de azúcar presentan fallas como: desgaste, fisuras y quemaduras. Un proyecto de investigación acerca de la tribología del par bronce-acero es realizado por la Escuela de Ingeniería Mecánica de la Universidad del Valle, junto con CENICAÑA y el Ingenio Manuelita, y se basa en la identificación del mecanismo de desgaste presente y en el análisis de las propiedades tribológicas de los elementos del par. Dentro del proyecto de investigación se diseñó y construyó un tribómetro de desgaste adhesivo normalizado tipo bloque-anillo, para reproducir las condiciones de operación de los molinos de caña y se ensayaron diferentes combinaciones de materiales para la chumacera: bronce SAE 67 y 64, con diferentes lubricantes: grasa y aceite. A través del uso de microscopia óptica y electrónica se pudo identificar el mecanismo de desgaste en bronces y guijos. De acuerdo a los resultados obtenidos se pudo concluir que la mejor combinación tribológica fue el par acero SAE 1045 -bronce SAE 64 y aceite como lubricante para los molinos de caña de azúcar.

Accurate prediction of the formability in multistage forming process is very challenging due to the dynamic shift of limiting strain during the different stages depending on the tooling geometry and selection of the process parameters. Hence, in the present work, a mathematical framework is proposed for the estimation of stress based and polar effective plastic strain-forming limit diagram (r- and PEPS-FLD) using the Barlat-89 anisotropic plasticity theory in conjunction with three different hardening laws such as Hollomon, Swift, and modified Voce equation. Two-stage stretch forming setup had been designed and fabricated to first prestrain in an in-plane stretch forming setup, and, subsequently, limiting dome height (LDH) testing was carried out on the prestrained blanks in the second stage to evaluate the formability. The finite element (FE) analysis of these two-stage forming process was carried out in LS-DYNA for automotive grade dual-phase (DP) and interstitial-free (IF) steels, and the r-FLD and PEPS-FLD were used as damage model to predict failure. The predicted forming behaviors, such as LDH, thinning development, and the load progression, were validated with the experimental results. It was found that the LDH in the second stage decreased with increase in the prestrain amount, and both the r-FLD and PEPS-FLD could be able to predict the formability considering the deformation histories in the present multistage forming process with complex strain path.

RESUMEN: El aumento de la conciencia ambiental y una regulación más estricta de las emisiones atmosféricas han permitido desarrollar las mezclas asfálticas tibias (WMA). Estas mezclas se producen a una temperatura menor que las mezclas en calientes reduciendo la viscosidad del asfalto y disminuyendo los costos de producción por la reducción en el consumo de combustible. Para reducir la viscosidad a bajas temperaturas se utilizan aditivos químicos sin embargo es la primera vez que se utiliza en Colombia el aceite crudo de palma como aditivo reductor de viscosidad del asfalto. Colombia es el primer productor de aceite de palma en América Latina y el cuarto a nivel mundial. La gradación de la mezcla se obtuvo con 54.1% de gruesos, 41.7% de finos y 4.2% de llenante utilizando cal hidratada, y se mezcló con asfalto de penetración 60-70, modificado con crudo de palma al 1%. El diseño se realizó por el método Marshall, la temperatura de producción de la mezcla se redujo, así como la viscosidad del asfalto y se mejoró el desempeño de la mezcla asfáltica tibia comparada con la mezcla asfáltica en caliente.

A pesar de que el método de distribución de momentos (MDM) desarrollado por Hardy Cross en 1932 ha sido superado por métodos de cálculo más poderosos como el método de Elementos Finitos este es parte importante de los cursos de análisis y diseño estructural y todavía una herramienta utilizada en la práctica profesional por los ingenieros estructurales. El objetivo principal de esta publicación es presentar una versión extendida del MDM para la estabilidad lateral, el análisis de primer y de segundo-orden de vigas indeterminadas y estructuras aporticadas hechas de vigas y columnas de sección transversal simétrica. Los efectos combinados de las deformaciones por fl exión y por cortante, cargas axiales y conexiones semirrígidas son incluidos utilizando la formulación "modifi cada" de la cortante propuesta por Haringx en 1947 y descrita por Timoshenko y Gere (1961). El método propuesto, el cual incluye los efectos de la componente inducida por la fuerza axial aplicada en la cortante a la lo largo de cada elemento, tiene las siguientes ventajas: 1) puede ser utilizado en el análisis de primer y segundo orden y estabilidad lateral de estructuras aporticadas indeterminadas hechas de vigas y columnas con conexiones rígidas, semirrígidas y simples; 2) los efectos de las conexiones son condensados en los coefi cientes de rigidez a fl exión y en los momentos fi jos sin introducir grados de libertad ni ecuaciones de equilibrio adicionales; y 3) el método es exacto, poderoso, práctico, versátil y es una herramienta excelente de enseñanza. Estudios analíticos indican que los efectos de la cortante, de las conexiones semirrígidas y de la carga axial incrementan las defl exiones laterales y afectan los momentos internos y las reacciones en estructuras aporticadas. Estos efectos deben tenerse en cuenta particularmente en estructuras esbeltas y cuando son hechas de vigas o columnas con área a cortante relativamente pequeña (en celosía) con rigidez a cortante GA s del mismo orden de magnitud que la rigidez a fl exión EI/L 2 (situación que ocurre en columnas cortas hechas de materiales laminados compuestos con un modulo a cortante G mucho menor que el de elasticidad E). Estos efectos llegan a ser incluso más importantes cuando los apoyos externos no son perfectamente empotrados. Tres ejemplos son incluidos en un artículo adjunto, los cuales muestran la efectividad del método propuesto.

En este trabajo se presenta una recopilación bibliográfica de los recubrimientos inorgánicos, híbridos, con partículas dispersas, depositados sobre aleaciones de acero inoxidable por medio de la técnica sol-gel. A partir de estos recubrimientos es posible la modificación de las propiedades superficiales de estas aleaciones metálicas, en busca de mejorar su resistencia química, además del grado de biocompatibilidad cuando están expuestas a ambientes fisiológicos

Dental ceramics are the preferred materials for oral restoration due to some characteristics, such as adequate esthetics, high fracture strength and chemical stability. Currently, dental professionals have a large amount of ceramic systems to choose from, all of them having small differences regarding their chemistry, processing temperatures, mechanical strength and clinical applications. These differences lead to classification systems that are difficult to understand by professionals outside the dental field. The aim of this work is to review the current dental ceramic systems and present them from a compositional perspective to assure the comprehension of these materials by professionals who belong to the Biomedical Engineering field. A great effort was made to avoid classification methods imposed by manufacturers and to obtain a quick compilation of available information from the literature allowing the reader to have a general view of the stateoftheart on dental ceramics. KEYWORDS: Ceramic systems, feldspathic porcelain, leucite, zirconium oxide, glassceramics, mechanical and physical properties.

En este artículo se presenta la revisión del estado del arte sobre la adición de nanopartículas al cemento Pórtland. Se muestra cómo la nanotecnología está empezando a llegar a este material de construcción buscando generar hormigones de alto desempeño y cómo varios investigadores han incorporado algunos tipos de partículas nanométricas para evaluar fundamentalmente el desempeño físico y mecánico de los cementos adicionados con éstas contra cementos con adiciones de comportamiento más conocido como el humo de sílice, escorias de alto horno y las cenizas volantes.

RESUMEN: Se presentan los resultados de un estudio experimental de flotación de feldespato usando mezcla de colectores. La evaluación de la hidrofobicidad de las partículas se realiza mediante la medición del potencial Z de los principales minerales del sistema particulado (Cuarzo-Feldespato) Se encuentra que la mezcla de colectores mejora fuertemente la hidrofobicidad del feldespato, mientras que se disminuye la flotabilidad del cuarzo, lo cual está asociado a fuertes cambios del potencial Z.

Modern research in automotive crashworthiness relies extensively on explicit finite element analysis. Crash analysts require deep understanding of finite element method and explicit time integration routines. This work presents the most important elements of the theory behind the mathematical apparatus of transient explicit finite element method and explains the loop algorithm of model analysis commonly used in commercial and publicly available solvers. Correctitude of the presented concepts and methodology are verified by using a computation example of a simple lumped mass spring system subjected to impact loading. The model is analysed both by using a commercial crash solver and by using a proposed MATLAB impact algorithm.

This study deals with additive manufacturing (AM) products. Employing AM technology, complex-shaped, and lightweight parts can be fabricated using the aluminum alloy, AlSi10Mg. Typically, AM of this alloy is performed by laser powder bed fusion (LPBF). The mechanical properties of LPBF products are crucial for many engineering applications. Therefore, there have been efforts to measure the dynamic and quasi-static properties of such products. However, both the dynamic and quasi-static shear behaviors of this alloy are yet to be investigated. The present study is focused on experimentally investigating the shear behavior of LPBF AlSi10Mg. Quasi-static shear tests were performed according to the ASTM B565 protocol, whereas dynamic shear tests were conducted using a standard split Hopkinson pressure bar equipped with an innovative sample holder that generates pure shear in a sample. The results of the performed tests showed that as the shear load rate increased, the shear strength considerably increased. In addition, in the quasi-static regime, the shear strength was practically independent of the product build direction. In contrast, under the dynamic shear conditions, samples built horizontally failed at a shear strength approximately 10% lower than that of those manufactured vertically. To investigate the build orientation effect on the shear behavior, this study conducted extensive microstructural characterization along with fracture analysis. Crack nucleation and propagation were analyzed in view of the effects of the unique microstructural characteristics of the LPBF AlSi10Mg, including the morphologies of the melt pool boundaries. The results obtained in this study suggested that for engineering applications in which dynamic loads are expected, the build orientation of AlSi10Mg parts produced using LPBF technology must be considered.

RESUMEN: Se presentan los resultados sobre la destilación extractiva de mezclas etanol-agua con polialcohol PAW y las sales CaCl2 y KCOOCH3 disueltas en él, utilizando una relación volumétrica 1:1 de etanol–agua a polialcohol y una concentración de 0.1 g/mL de sal en ...

This paper investigates the impact of stronger roof structures on vehicle handling and stability .Baseline roof structures, their strength to weight ratios (SWR) and static stability factor (SSF) were considered. The effect on center of gravity (CG) height location from improving the strength to weight ratios to about 4 was considered through finite element analysis. The weight of the proposed strengthening is calculated. The magnitude of such effects on handling and stability of passenger vehicles was comparatively and analytically determined. The increase in track width required to offset the reduction in static stability factor due to increase in CG height was determined. To confirm the findings, an example series of double lane change fishhook maneuvers were conducted with and without the simulated weight of a reinforced roof structure. Statistical data from current production vehicles and weight impact estimates derived from finite element (FE) analyses of reinforced roof structures were used along with empirical handling test data. The results indicate that the effect on handling of stronger roof structures is negligible. Other factors affecting weight such as non-safety related accessories, load, passengers, luggage and fuel quantity were determined to have significantly higher impact compared to the additional weight from reinforced roof structures.
Improved roof strength in this study can be accomplished without increasing rollover propensity or measurable impacts on stability and handling. An analysis of the effects on handling and stability of stronger roof structures has not been previously been published evaluating potential effects of increases in roof strength.