Papers by Daniel Vlasceanu
Structural Health Monitoring (SHM) represents a method of monitoring and assessment of the struct... more Structural Health Monitoring (SHM) represents a method of monitoring and assessment of the structural state of a certain component, in terms of damage identification, damage classification and monitoring of deformations and loads. The structure and purpose of different SHM methods are presented, with a review of the main types of sensors and monitoring methods available. Recent trends in implementing SHM methods in composite applications are presented, especially in aerospace structures. Also, the main advantages and disadvantages of SHM methods are being highlighted and the potential that these systems have in the technological future. The main purpose of the presented survey is to assess the best method to realize a future model of a new composite blade, equipped with sensors, that will replace the current metal tail rotor blade which equips the IAR330 military transport helicopter used by the Romanian Air Force.
Aerospace, Jul 19, 2023
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Materiale Plastice, Jul 1, 2019
Determining the dynamic properties in the frequency domain of aircraft structural elements is a v... more Determining the dynamic properties in the frequency domain of aircraft structural elements is a very important aspect taken into account nowadays by aircraft manufacturers. One of the helicopters most exposed element to structural vibrations is the rotor blade, thus making its construction and the material choice a very important decision. Finite element methods can be used to assess the vibrational properties of such elements, in order to prove their airworthiness. The main objective of the article is to study how the use of different materials affects the structural behavior of the helicopter tail rotor blade, with regard to the frequencies at which these structures are prone to vibrate. The blade profile is the NACA0012 symmetric airfoil used on the IAR330 helicopter tail rotor blade and the main objective is to identify the best inner core material, while highlighting the importance of polymeric materials.
Procedia Engineering, 2014
The osteosynthesis of transcondylar humeral fractures is an important branch of the upper limb tr... more The osteosynthesis of transcondylar humeral fractures is an important branch of the upper limb traumatology. The boneimplant assembly has to be strong enough to resist the high loads arising during the early rehabilitation program, while keeping the soft tissue stripping to a minimum. Using the finite element method, this study compares two alternatives of stabilization of this kind of fractures by means of a new type of implant, less expensive than the existing locking plates and, more importantly, minimally-invasive. This implant comprises two modified cortical screws (one for each column of the distal humerus) and a Kirschner wire (or a partial threaded screw) which locks the screws transversally at the epiphysis. The screws can be placed in the middle of the columns of the distal humerus or with an eccentricity, immediately under the cortical shell of the bone. Using data from distal humerus CT scans, two CAD (Solidworks) models of the bone and implants were produced, imported, edited, loaded and analysed in a finite element analysis program (Ansys). The results indicate that the subcortical placement of the screws is more favorable than the intracancellous one, leading to increased stiffness of the bone-implant assembly. This stage the first refinement of this method and this study will be followed by computer, in-vitro and clinical studies, comparing the behavior of this alternative to the existing standard implants.
Mechanics of Materials, Sep 1, 2020
Abstract Three-dimensional printing of functional parts for different applications has increasing... more Abstract Three-dimensional printing of functional parts for different applications has increasingly attracted the interest of industries, owing to advantages such as seamless customization, a simplified supply chain, and on-demand production of prototypes. Hence, the mechanical properties of 3D prints subjected to different types of loads and exposed to factors specific to working and storage conditions must be studied. In this context, this study focuses on experimentally investigating the mechanical behavior of 3D-printed acrylonitrile butadiene styrene (ABS) specimens exposed to shelf life and multiple sterilizations, as these conditions are typical for medical instruments in a hospital environment. Tensile and flexural specimens were manufactured using fused deposition modeling (FDM) and were randomly divided into two groups. One group was used for evaluating the medium-term natural aging (shelf life) and as the control group for the sterilized specimens. Specimens in the second group underwent repeated sterilizations. Mechanical tests were performed on specimens from both groups, and comparisons of the results were made across groups and within individual groups. The fracture patterns of sterilized and non-sterilized specimens were characterized using scanning electron microscopy (SEM) and industrial computer tomography (CT) was performed to understand the experimental findings. The results show that natural aging and repeated sterilizations do not influence mechanical performance in terms of stiffness and strength in tension and flexion. However, other properties, such as creep, wear, and fatigue should also be considered with regard to sterilization, depending on the instrument functionality.
Materials, Nov 14, 2022
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Materiale Plastice, Dec 30, 2018
This paper presents a study undertaken following the collaboration between specialists in two mul... more This paper presents a study undertaken following the collaboration between specialists in two multidisciplinary fields, namely engineering and medicine. It was aimed at solving a practical problem by developing of a handle for use in orthopedic surgery. Specific engineering tools, knowledge and processes and methods were used for accomplishing this task. Tailoring devices according to surgeons preferences for ensuring an ergonomic use is an important criterion alongside functional and sterilization requirements, cost and fabrication time, 3D printing representing a feasible manufacturing solution as this research proves. The article details the steps required to complete the final product: design and redesign, numerical analysis, prototypes manufacturing and testing. To perform the numerical analysis that highlights the device mechanical behavior, finite element method was used in assessing different handle designs.
Macromolecular Symposia, Feb 1, 2020
In the study of the aerodynamic load applied by the air on the rotating helicopter blade, it is i... more In the study of the aerodynamic load applied by the air on the rotating helicopter blade, it is important to know that the values obtained from the numerical analysis are as close to reality as possible, within an acceptable limit. Therefore, in order to realize and obtain a pertinent result from a structural analysis, based on pressure loads obtained from the airflow surrounding the blade, it is important that the fluid flow results are certified by comparison with experimental result. In order to achieve this purpose, the tail rotor blade of the Romanian Air Force IAR330 helicopter has been modeled using Ansys Workbench and by using Fluid Flow, the values of the pressures on the main blade surfaces have been determined. The experimental values of the aerodynamic pressure have been determined using a 1:1 scale model of the blade, placed in the subsonic aerodynamic wind tunnel at INCAS Bucharest.
Materials Science Forum, Jun 1, 2019
The purpose of this paper is to evaluate the influence of 3D printing parameters (i.e. print spee... more The purpose of this paper is to evaluate the influence of 3D printing parameters (i.e. print speed, infill density, infill patterns) on the elastic and mechanical properties (i.e. Young modulus, yield limit, ultimate tensile strength). These properties have been determined experimentally on different specimens subjected to tensile loading using a universal testing machine INSTRON 8872. For these experimental investigations, the test specimens were manufactured in accordance to ASTM standards, modifying the following printing parameters: print speed, infill density, infill patterns. The influence of printing parameters on elastic and mechanical properties is necessary for a better understanding of the material behavior necessary in modelling and design of some type of structures manufactured using 3D printing method.
Polymers
Additively manufactured wrist–hand orthoses (3DP-WHOs) offer several advantages over traditional ... more Additively manufactured wrist–hand orthoses (3DP-WHOs) offer several advantages over traditional splints and casts, but their development based on a patient’s 3D scans currently requires advanced engineering skills, while also recording long manufacturing times as they are commonly built in a vertical position. A proposed alternative involves 3D printing the orthoses as a flat model base and then thermoforming them to fit the patient’s forearm. This manufacturing approach is faster, cost-effective and allows easier integration of flexible sensors as an example. However, it is unknown whether these flat-shaped 3DP-WHOs offer similar mechanical resistance as the 3D-printed hand-shaped orthoses, with a lack of research in this area being revealed by the literature review. To evaluate the mechanical properties of 3DP-WHOs produced using the two approaches, three-point bending tests and flexural fatigue tests were conducted. The results showed that both types of orthoses had similar stif...
Polymers
Carbon fiber-reinforced composites represent a broadly utilized class of materials in aeronautica... more Carbon fiber-reinforced composites represent a broadly utilized class of materials in aeronautical applications, due to their high-performance capability. The studied CFRP is manufactured from a 3K carbon biaxial fabric 0°/90° with high tensile resistance, reinforced with high-performance thermoset molding epoxy vinyl ester resin. The macroscale experimental characterization has constituted the subject of various studies, with the scope of assessing overall structural performance. This study, on the other hand, aims at evaluating the mesoscopic mechanical behavior of a single-ply CFRP, by utilizing tensile test specimens with an average experimental study area of only 3 cm2. The single-ply tensile testing was accomplished using a small scale custom-made uniaxial testing device, powered by a stepper motor, with measurements recorded by two 5-megapixel cameras of the DIC Q400 system, mounted on a Leica M125 digital stereo microscope. The single-ply testing results illustrated the orth...
Materialele cromoplastice pot fi incluse in categoria materialelor ce prezintă o curbă caracteris... more Materialele cromoplastice pot fi incluse in categoria materialelor ce prezintă o curbă caracteristică de tip Prandtl. Ele au fost obţinute în România, la Institutul de Cercetări Chimice din Bucureşti. Materialul cromoplastic este un polimer ce prezintă o comportare liniară-perfect plastică la tracţiune şi îşi schimbă culoarea in zonele deformate plastic: el devine alb atunci când curgerea are loc la tractiune şi respectiv negru atunci când curgerea se produce sub acţiunea unor tensiuni de compresiune. În acest articol, se prezintă teste de răsucire pură, realizate pentru epruvete de tip Iosipescu, confecţionate din material cromoplastic. Metoda Iosipescu este extrem de răspândită în analiza experimentală pe plan mondial. Înainte de aceste încercări, au fost realizate teste de tracţiune pentru determinarea caracteristicilor mecanice şi ale constantelor elastice ale materialului epruvetelor. Aceste date au fost utilizate în analizele numerice cu metoda elementelor finite, pentru evalu...
Key Engineering Materials, Mar 1, 2015
Dental medicine represents a very important part of our life. As our appearance or looks is a maj... more Dental medicine represents a very important part of our life. As our appearance or looks is a major concern for us, a beautiful smile can improve our life. Moreover, our teeth health reflects on our overall health. This paper presents a method for highlighting the differences between a natural tooth and a prosthetic one. In order to determine the stress distribution in teeth during the use of prosthetics pivots, several virtual geometric models of the teeth were created (canine, first premolar, first molar and second molar), both in their natural form and when using pivots. The results obtained from these analyses were compared in order to reveal the behavior of a prosthetic tooth during normal life loads. Such results of real life behavior can be used by dental medics in order to predict the life span of restored teeth.
Macromolecular Symposia, 2020
In the study of the aerodynamic load applied by the air on the rotating helicopter blade, it is i... more In the study of the aerodynamic load applied by the air on the rotating helicopter blade, it is important to know that the values obtained from the numerical analysis are as close to reality as possible, within an acceptable limit. Therefore, in order to realize and obtain a pertinent result from a structural analysis, based on pressure loads obtained from the airflow surrounding the blade, it is important that the fluid flow results are certified by comparison with experimental result. In order to achieve this purpose, the tail rotor blade of the Romanian Air Force IAR330 helicopter has been modeled using Ansys Workbench and by using Fluid Flow, the values of the pressures on the main blade surfaces have been determined. The experimental values of the aerodynamic pressure have been determined using a 1:1 scale model of the blade, placed in the subsonic aerodynamic wind tunnel at INCAS Bucharest.
Materials Today: Proceedings
Romanian Journal of Oral Rehabilitation, 2019
Aim of the study The purpose of this finite element analyze study was to evaluate the influence o... more Aim of the study The purpose of this finite element analyze study was to evaluate the influence of implant macrodesign when using two different types of implants, soft tissue level – and bone level implants, in a maxillary bone site that previously underwent alveolar ridge preservation and to compare the stress/ strain values occurring in the bone and at the implant-bone interface after the application of the static and dynamic forces. Material and methods A three-dimensional (3D) finite element model was created to evaluate the magnitude and distribution of the stress in the peri-implant bone of a single implant with a crown cemented to a titanium abutment. Results The results of the study showed that the values of total movement, the distribution of equivalent tension and the tension along the implant axis were lower for the tissue level implants when compared to bone level implants. Conclusions Stress/strain distribution patterns were influenced by implant collar/neck design in t...
Acta Universitatis Cibiniensis. Technical Series, 2020
Structural Health Monitoring (SHM) represents a method of monitoring and assessment of the struct... more Structural Health Monitoring (SHM) represents a method of monitoring and assessment of the structural state of a certain component, in terms of damage identification, damage classification and monitoring of deformations and loads. The structure and purpose of different SHM methods are presented, with a review of the main types of sensors and monitoring methods available. Recent trends in implementing SHM methods in composite applications are presented, especially in aerospace structures. Also, the main advantages and disadvantages of SHM methods are being highlighted and the potential that these systems have in the technological future. The main purpose of the presented survey is to assess the best method to realize a future model of a new composite blade, equipped with sensors, that will replace the current metal tail rotor blade which equips the IAR330 military transport helicopter used by the Romanian Air Force.
Mechanics of Materials, 2020
Abstract Three-dimensional printing of functional parts for different applications has increasing... more Abstract Three-dimensional printing of functional parts for different applications has increasingly attracted the interest of industries, owing to advantages such as seamless customization, a simplified supply chain, and on-demand production of prototypes. Hence, the mechanical properties of 3D prints subjected to different types of loads and exposed to factors specific to working and storage conditions must be studied. In this context, this study focuses on experimentally investigating the mechanical behavior of 3D-printed acrylonitrile butadiene styrene (ABS) specimens exposed to shelf life and multiple sterilizations, as these conditions are typical for medical instruments in a hospital environment. Tensile and flexural specimens were manufactured using fused deposition modeling (FDM) and were randomly divided into two groups. One group was used for evaluating the medium-term natural aging (shelf life) and as the control group for the sterilized specimens. Specimens in the second group underwent repeated sterilizations. Mechanical tests were performed on specimens from both groups, and comparisons of the results were made across groups and within individual groups. The fracture patterns of sterilized and non-sterilized specimens were characterized using scanning electron microscopy (SEM) and industrial computer tomography (CT) was performed to understand the experimental findings. The results show that natural aging and repeated sterilizations do not influence mechanical performance in terms of stiffness and strength in tension and flexion. However, other properties, such as creep, wear, and fatigue should also be considered with regard to sterilization, depending on the instrument functionality.
Materials Science Forum, 2019
The purpose of this paper is to evaluate the influence of 3D printing parameters (i.e. print spee... more The purpose of this paper is to evaluate the influence of 3D printing parameters (i.e. print speed, infill density, infill patterns) on the elastic and mechanical properties (i.e. Young modulus, yield limit, ultimate tensile strength). These properties have been determined experimentally on different specimens subjected to tensile loading using a universal testing machine INSTRON 8872. For these experimental investigations, the test specimens were manufactured in accordance to ASTM standards, modifying the following printing parameters: print speed, infill density, infill patterns. The influence of printing parameters on elastic and mechanical properties is necessary for a better understanding of the material behavior necessary in modelling and design of some type of structures manufactured using 3D printing method.
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Papers by Daniel Vlasceanu