Evaluating the Impact of Shape on Finite Element Simulations in a Medical Context

2009 ◽  
pp. 95-109 ◽  
Author(s):  
Lars Walczak ◽  
Frank Weichert ◽  
Andreas Schröder ◽  
Constantin Landes ◽  
Heinrich Müller ◽  
...  
Keyword(s):  
Finite Element ◽  
Finite Element Simulations ◽  
Medical Context ◽  
The Impact

A Study of the Importance of Three Key Parameters on the Separation Modes of Adhering Microcontacts

2007 ◽  
Author(s):  
Yan Du ◽  
George G. Adams ◽  
Nicol E. McGruer ◽  
Izhak Etsion
Keyword(s):  
Finite Element ◽  
Finite Element Simulations ◽  
The Impact ◽  
Theoretical Stress

Three key parameters describing contacts with adhesion were identified in previous investigations. Here a series of finite element simulations of a single load/unload cycle of a contact are performed to study the impact of each of these parameters. The results show that one parameter (S) is most important in determining the separation mode, i.e. brittle or ductile separation. Smaller S leads to brittle separation while larger S gives ductile separation. The transition between the two separation modes occurs at about S = 1.2 which corresponds to the theoretical stress being somewhat greater than the hardness.

Ductile Fracture Characterization of an X70 Steel: Re-Interpretation of Classical Tests Using the Finite Element Technique

2008 ◽  
Author(s):  
Philippe Thibaux ◽  
Se´bastien Mu¨ller ◽  
Benoit Tanguy ◽  
Filip Van Den Abeele
Keyword(s):  
Finite Element ◽  
Crack Initiation ◽  
Pipeline Steel ◽  
Damage Model ◽  
Base Material ◽  
Steel Production ◽  
Crack Arrest ◽  
Finite Element Simulations ◽  
Charpy Test ◽  
The Impact

The crack arrest capacity of a linepipe is one of the most important material parameter for such components. In current design codes, it is expressed as the energy absorbed by a CVN impact test. This prescribed impact energy for a given pipeline is typically between 50 and 120J, depending on the grade of the material, the pressure and the dimensions of the pipe. The continuous improvement of steel production has lead to the situation that the impact values achieved in standard pipeline steel production are much larger than 200J for the base material. The question of the significance of these high impact energies can be raised, particularly considering that no correlation has been found between CVN values and crack arrest properties of very high strength materials (X100–X120). In this investigation, instrumented Charpy tests and notched tensile tests were performed on an X70 material. The same tests were also simulated using the finite element method and the Gurson-Tvergaard-Needleman damage model. The combination of supplementary experimental information coming from the instrumentation of the Charpy test and finite element simulations delivers a different insight about the test. It is observed that the crack does not break the sample in 2 parts in ductile mode. After 6–7mm of propagation, the crack deviates and stops. The propagation stops when the crack meets the part of the sample becoming wider due to bending. Finite element simulations proved that it results in a quasi constant force during a displacement of the hammer of almost 10mm. The consequence is that more than 25% of the energy is dissipated in a different fracture mode at the end of the test. Finite element simulations proved also that damage is already occurring at the maximum of the load, but that damage has almost no influence on the load for two-thirds of the displacement at the maximum. In the case of the investigated steel, it means that more than 27J, as often mentioned in standards for avoidance of brittle failure, are dissipated by plastic bending before the initiation of the crack. From the findings of this study, one can conclude that the results of the Charpy test are very sensitive to crack initiation and that only a limited part of the test is meaningful to describe crack propagation. Therefore, it is questionable if the Charpy test is adapted to predict the crack arrest capacity of steels with high crack initiation energy.

EFFECTS OF STRAIN RATE DEPENDENCY OF MATERIAL PROPERTIES IN LOW VELOCITY IMPACT

2008 ◽  
Vol 22 (09n11) ◽  
pp. 1165-1170 ◽  
Author(s):  
HIROFUMI MINAMOTO ◽  
ROBERT SEIFRIED ◽  
PETER EBERHARD ◽  
SHOZO KAWAMURA
Keyword(s):  
Finite Element ◽  
Strain Rate ◽  
Yield Stress ◽  
Coefficient Of Restitution ◽  
Finite Element Simulations ◽  
Material Behavior ◽  
Rate Dependency ◽  
Rate Dependent ◽  
Strain Rate Dependency ◽  
The Impact

Impact processes are often analyzed using the coefficient of restitution which represents the kinetic energy loss during impact. In this paper the effect of strain rate dependency of the yield stress on the coefficient of restitution is investigated experimentally and numerically for the impact of a steel sphere against a steel rod. Finite Element simulations using strain-rate dependent material behavior are carried out. In addition, Finite Element simulations with elastic-plastic material behavior, which ignore the strain rate dependency, are carried out as well as elastic material behavior. Comparisons between the experiments and the simulations using strain-rate dependent material behavior show good agreement, and also prove the strong dependency of the coefficient of restitution on the strain rate dependency of the yield stress for steel. The results from both, the experiments and the simulations show also the strong influence of the wave propagation in the rod on the coefficient of restitution.

Low-frequency impact sound of timber floors: A finite element–based study of conceptual designs

2020 ◽  
pp. 1351010X2091787
Author(s):  
Jörgen Olsson ◽  
Andreas Linderholt
Keyword(s):  
Finite Element ◽  
Low Frequency ◽  
Sound Transmission ◽  
Human Perception ◽  
Finite Element Simulations ◽  
Building Industry ◽  
Frequency Range ◽  
Floor Surfaces ◽  
The Impact ◽  
Selection Of

Traditionally, product development concerning acoustics in the building industry is measurement oriented. For lightweight floors, frequencies that are lower than the frequency range for heavy concrete floors are an issue. The frequency range of from 50 Hz down to 20 Hz influences the human perception of impact sound in multi-story apartment buildings with lightweight floor constructions, such as timber floors, for example. It is well known that a lower frequency range of interest makes finite element simulations more feasible. Strategies for reducing impact sound tend to be less straightforward for timber floors because they have a larger variation of designs when compared to concrete floors. This implies that reliable finite element simulations of impact sound can save time and money for the building industry. This study researches the impact sound transmission of lightweight timber floors. Frequency response functions, from forces on excitation points to sound pressure in the receiving cavity below, are calculated. By using fluid elements connected to reflection-free boundary elements under the floors in the models, the transmission and insulation can be studied without involving reverberation. A floor model with a hard screed surface will have a larger impact force than a softer floor, although this issue seems less pronounced at the lowest frequencies. To characterize floor surfaces, the point mobilities of the impact points are also calculated and presented. The vibration and sound transmission levels are dependent on the selection of the excitation points.

scholarly journals On the Proportionality of Damage Rule in Finite Element Simulations of the Ductile Failure

2014 ◽  
Vol 980 ◽  
pp. 189-193 ◽  
Author(s):  
František Šebek ◽  
Jiří Hůlka ◽  
Petr Kubík ◽  
Jindřich Petruška
Keyword(s):  
Finite Element ◽  
Ductile Failure ◽  
Tensile Tests ◽  
Finite Element Simulations ◽  
Damage Rate ◽  
Slant Fracture ◽  
Aluminum Alloy 2024 ◽  
Coulomb Criterion ◽  
The Impact ◽  
Damage Rule

Extended Mohr–Coulomb criterion which is uncoupled, therefore the plasticity is not influenced by the damage, was selected and calibrated. Experiments on the aluminum alloy 2024-T351 were carried out. Further, the impact of the damage rule proportionality was investigated. The damage exponent was sequentially held 1, 2 and 3, respectively. Therefore, the influence of the damage rate on the damage failure in finite element simulations was examined. Numerical simulations of the tensile test of smooth and notched cylindrical specimens and flat grooved specimen were performed. It is also shown that there is inability to predict slant fracture by uncoupled models for flat grooved specimen and in the final phase of tensile tests of cylindrical specimens.

Modeling of Impact Response of Composite Graded Structure

2011 ◽  
Author(s):  
M. Ali ◽  
J. Hoffman ◽  
J. Clark ◽  
S. Takak
Keyword(s):  
Finite Element ◽  
Total Energy ◽  
Local Deformation ◽  
Functionally Graded ◽  
Finite Element Simulations ◽  
Impact Behavior ◽  
Banana Peel ◽  
Graded Structure ◽  
The Impact ◽  
Dynamic Crushing

The work presented in this paper is a continuation of a study on exploring energy absorbing characteristics of a composite functionally graded structure found in a banana peel [1]. The impact behavior of peel structure under strain rates ranging from 4000 s−1 to 15000s−1 are studied. A modified mathematical model is presented, which calculates the initial dynamic crushing stresses of the structure at different impact velocities. The model outputs are compared with finite element simulations for the initial crushing stress, densification strain, global and local deformation modes, reactive force pulse, and total energy absorbed. A reasonable agreement is found between the proposed model and finite element simulations in determining the initial dynamic crushing stress and total energy absorbed by the structure.

scholarly journals Study and Optimization of a 600V Pseudo-Vertical GaN-on-Silicon Rectifier by Finite Element Simulations

2016 ◽  
Vol 858 ◽  
pp. 1190-1193
Author(s):  
Amira Souguir-Aouani ◽  
Nicolas Thierry-Jebali ◽  
Dominique Tournier ◽  
Arnaud Yvon ◽  
Emmanuel Collard ◽  
...  
Keyword(s):  
Finite Element ◽  
Breakdown Voltage ◽  
Doping Concentration ◽  
Impact Analysis ◽  
Finite Element Simulations ◽  
Geometrical Parameters ◽  
Guard Ring ◽  
Good Efficiency ◽  
Schottky Rectifier ◽  
The Impact

This work presents the impact analysis of physical and geometrical parameters on the on-resistance and the breakdown voltage in order to optimize a 600 V pseudo-vertical GaN/Si Schottky rectifier. The results by finite element simulations indicate that the most influent parameter on the resistance is the thickness of the n+ layer. Regarding reverse specifications, simulations show that a good efficiency of the “Mesa + Guard Ring” is achieved for a guard ring doping concentration higher than Na=5×1017 cm-3.

Low Velocity Impact Analysis of Functionally Graded Circular Plates

Aerospace ◽  
2006 ◽  
Author(s):  
Reid A. Larson ◽  
Anthony Palazotto
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Functionally Graded ◽  
Finite Element Simulations ◽  
Low Velocity Impact ◽  
Impact Event ◽  
Circular Plates ◽  
Functionally Graded Plate ◽  
Structural Applications ◽  
The Impact

Functionally graded materials (FGMs) are advanced composites with mechanical properties that vary continuously through a given dimension. FGMs have generated a great deal of interest in recent years due to their flexibility for use in a wide variety of environments, including those structural applications where extreme thermal and corrosion resistance are required. In this paper, analyses will be performed given an impact event that occurs between a spherical projectile and a functionally graded circular plate with both simply supported and clamped boundary conditions. The circular plates are constructed using zirconia and aluminum as constituents blended through the thickness in various configurations using a power-law distribution. The analyses will assume that the classical rule-of-mixtures (ROM) approach will sufficiently describe the macro-mechanical properties for the graded plates. First, impact response equations developed for composite materials are applied to estimate the impact force and maximum deflection of a functionally graded plate. Next, the elastic wave response of the functionally graded plate is predicted using the classic wave equation applied to the graded plate and the impact event. Finally, finite element simulations are developed to compare the analytical solutions to numerical results from a commercial software program. The degree of correlation between the analytical predictions and the finite element simulations will provide insight into the validity of the ROM assumption and provide a baseline for estimating impact behavior of functionally graded plates.

Analysis for the Impact of an Engine Hood to a Radiator Support Frame in a Car Body Structure

2013 ◽  
Vol 535-536 ◽  
pp. 453-456
Author(s):  
Ting Fang Hung ◽  
Chia Che Chang ◽  
Fuh Kuo Chen
Keyword(s):  
Finite Element ◽  
Computing Time ◽  
Element Model ◽  
Contact Spot ◽  
Finite Element Simulations ◽  
Element Size ◽  
Support Frame ◽  
Free Falling ◽  
The Impact ◽  
The Finite Element Model

The dynamic behavior of a radiator support frame impacted by a free-falling engine hood was studied with the use of the 3-D finite element simulations. The engine room including an engine hood, a radiator support frame, and a hood ledge was modeled first. Taking computing efficiency and accuracy into account, approaches for selecting element size, cleaning up complicated features of CAD files were then studied. In order to make the simulations more efficient, the contact spot weld model was adopted. To further reduce the computing time, a theoretical model was also proposed in the present study to calculate the instantaneous angular velocity of the engine hood at the incipient impact to the radiator support frame. The engine hood free-falling tests were also conducted to validate the finite element simulations. The consistency between the experimental data and the simulation results confirms the validity of the finite element model constructed in the present study.

The impact of sand slugs against beams and plates: Coupled discrete particle/finite element simulations

2013 ◽  
Vol 61 (8) ◽  
pp. 1798-1821 ◽  
Author(s):  
T. Liu ◽  
N.A. Fleck ◽  
H.N.G. Wadley ◽  
V.S. Deshpande
Keyword(s):  
Finite Element ◽  
Finite Element Simulations ◽  
Discrete Particle ◽  
The Impact
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