Finite Element Modeling of Electrostatic MEMS Including the Impact of Fringing Field Effects on Forces

2008 ◽  
Vol 6 (1) ◽  
pp. 115-120 ◽  
Author(s):  
Mohamed Boutaayamou ◽  
Ruth V. Sabariego ◽  
Patrick Dular
Keyword(s):  
Finite Element ◽  
Finite Element Modeling ◽  
Element Modeling ◽  
Field Effects ◽  
Electrostatic Mems ◽  
Fringing Field ◽  
The Impact

Experimentally validated predictive finite element modeling of the V0-V100 probabilistic penetration response of a Kevlar fabric against a spherical projectile

2018 ◽  
Vol 9 (4) ◽  
pp. 504-524 ◽  
Author(s):  
Gaurav Nilakantan
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Finite Element Modeling ◽  
Element Model ◽  
Ballistic Impact ◽  
Impact Testing ◽  
Woven Fabric ◽  
Projectile Impact ◽  
Element Modeling ◽  
The Impact

This work presents the first fully validated and predictive finite element modeling framework to generate the probabilistic penetration response of an aramid woven fabric subjected to ballistic impact. This response is defined by a V0-V100 curve that describes the probability of complete fabric penetration as a function of projectile impact velocity. The exemplar case considered in this article comprises a single-layer, fully clamped, plain-weave Kevlar fabric impacted at the center by a 0.22 cal spherical steel projectile. The fabric finite element model comprises individually modeled three-dimensional warp and fill yarns and is validated against the experimental material microstructure. Sources of statistical variability including yarn strength and modulus, inter-yarn friction, and precise projectile impact location are mapped into the finite element model. A series of impact simulations at varying projectile impact velocities is executed using LS-DYNA on the fabric models, each comprising unique mappings. The impact velocities and outcomes (penetration, non-penetration) are used to generate the numerical V0-V100 curve which is then validated against the experimental V0-V100 curve obtained from ballistic impact testing and shown to be in excellent agreement. The experimental data and its statistical analysis used for model input and validation, namely, the Kevlar yarn tensile strengths and moduli, inter-yarn friction, and fabric ballistic impact testing, are also reported.

scholarly journals Characterization of Maple and Ash Material Properties for the Finite Element Modeling of Wood Baseball Bats

2018 ◽  
Vol 8 (11) ◽  
pp. 2256 ◽  
Author(s):  
Joshua Fortin-Smith ◽  
James Sherwood ◽  
Patrick Drane ◽  
David Kretschmann
Keyword(s):  
Finite Element ◽  
Finite Element Modeling ◽  
Material Properties ◽  
Charpy Impact ◽  
Impact Testing ◽  
Charpy Test ◽  
Ball Impact ◽  
Element Modeling ◽  
The Impact ◽  
Baseball Bats

To assist in developing a database of wood material properties for the finite element modeling of wood baseball bats, Charpy impact testing at strain rates comparable to those that a wood bat experiences during a bat/ball collision is completed to characterize the failure energy and strain-to-failure as a function of density and slope-of-grain (SoG) for northern white ash (Fraxinus americana) and sugar maple (Acer saccharum). Un-notched Charpy test specimens made from billets of ash and maple that span the range of densities and SoGs that are approved for making professional baseball bats are impacted on either the edge grain or face grain. High-speed video is used to capture each test event and image analysis techniques are used to determine the strain-to-failure for each test. Strain-to-failure as a function of density relations are derived and these relations are used to calculate inputs to the *MAT_WOOD (Material Model 143) and *MAT_EROSION material options in LS-DYNA for the subsequent finite element modeling of the ash and maple Charpy Impact tests and for a maple bat/ball impact. The Charpy test data show that the strain-to-failure increases with increasing density for maple but the strain-to-failure remains essentially constant over the range of densities considered in this study for ash. The flat response of the ash data suggests that ash-bat durability is less sensitive to wood density than maple-bat durability. The available SoG results suggest that density has a greater effect on the impact failure properties of the wood than SoG. However, once the wood begins to fracture, SoG plays a large role in the direction of crack propagation of the wood, thereby determining if the shape of the pieces breaking away from the bat are fairly blunt or spear-like. The finite element modeling results for the Charpy and bat/ball impacts show good correlation with the experimental data.

Microchannel Design Study for 3D Microelectronics Cooling Using a Hybrid Analytical and Finite Element Method

2015 ◽  
Author(s):  
L.-M. Collin ◽  
V. Fiori ◽  
P. Coudrain ◽  
S. L. Lhostis ◽  
S. Chéramy ◽  
...  
Keyword(s):  
Finite Element ◽  
Finite Element Modeling ◽  
Heat Fluxes ◽  
Thermal Design ◽  
Air Cooling ◽  
Commercial Software ◽  
Total Thermal Resistance ◽  
Element Modeling ◽  
The Impact ◽  
Microelectronics Cooling

For microelectronics cooling, microchannels are a potential solution to ensure reliability without sacrificing compactness, as they require relatively small space to remove high heat fluxes compared to air cooling. However, designing microchannels is a complex task where simulation models become a forefront tool to investigate and propose new solutions to increase the chip thermal performances with minimal impact on other aspects. This work evaluates numerically the impact of microchannel cooling in a standalone chip and a 3D assembly of two stacked chips with localized heat sources. To do so, a modeling approach was developed to combine finite element modeling of conduction in the chip using commercial software with analytical relations to capture the heat transfer and fluid flow in the microchannels. This approach leverages the multiphysics and post-processing capabilities of commercial software, but avoids the extensive discretization that would normally be required in microchannels with full finite element modeling. The study shows that increasing the flow rate is not as beneficial as increasing the number of channels (with constant total cross-section area). The effect of heat spreading was also found to be critical, favoring thicker dies. When switching to 3D chip configuration, the interdie underfill layer significantly increases the total thermal resistance and must be considered for thermal design. This effect can be significantly alleviated by increasing the interdie thermal conductivity through adding copper micropillars.

scholarly journals Combining Satellite InSAR, Slope Units and Finite Element Modeling for Stability Analysis in Mining Waste Disposal Areas

2021 ◽  
Vol 13 (10) ◽  
pp. 2008
Author(s):  
Juan López-Vinielles ◽  
José A. Fernández-Merodo ◽  
Pablo Ezquerro ◽  
Juan C. García-Davalillo ◽  
Roberto Sarro ◽  
...  
Keyword(s):  
Finite Element ◽  
Stability Analysis ◽  
Slope Stability ◽  
Finite Element Modeling ◽  
Slope Stability Analysis ◽  
Radar Interferometry ◽  
Slope Failures ◽  
Element Modeling ◽  
Mining Areas ◽  
The Impact

Slope failures pose a substantial threat to mining activity due to their destructive potential and high probability of occurrence on steep slopes close to limit equilibrium conditions, which are often found both in open pits and in waste and tailing disposal facilities. The development of slope monitoring and modeling programs usually entails the exploitation of in situ and remote sensing data, together with the application of numerical modeling, and it plays an important role in the definition of prevention and mitigation measures aimed at minimizing the impact of slope failures in mining areas. In this paper, a new methodology is presented; one that combines satellite radar interferometry and 2D finite element modeling for slope stability analysis at a regional scale, and applied within slope unit polygons. Although the literature includes many studies applying radar interferometry and modeling for slope stability analysis, the addition of slope units as input data for radar interferometry and modeling purposes has, to our knowledge, not previously been reported. A former mining area in southeast Spain was studied, and the method proved useful for detecting and characterizing a large number of unstable slopes. Out of the 1959 slope units used for the spatial analysis of the radar interferometry data, 43 were unstable, with varying values of safety factor and landslide size. Out of the 43 active slope units, 21 exhibited line of sight velocities greater than the maximum error obtained through validation analysis (2.5 cm/year). Finally, this work discusses the possibility of using the results of the proposed approach to devise a proxy for landslide hazard. The proposed methodology can help to provide non-expert final users with intelligible, clear, and easily comparable information to analyze slope instabilities in different settings, and not limited to mining areas.

Finite Element Modeling of Rollover Crash Tests With Hybrid III Dummies

2007 ◽  
Author(s):  
Keith Friedman ◽  
John Hutchinson ◽  
Dennis Mihora
Keyword(s):  
Finite Element ◽  
Finite Element Modeling ◽  
The United States ◽  
Finite Element Models ◽  
Element Modeling ◽  
Roof Structure ◽  
Hybrid Iii ◽  
The Impact ◽  
Rollover Crash ◽  
Crash Tests

This paper reports on the finite element modeling of rollover crash tests with Hybrid III dummies. Finite element models of a vehicle design and the Hybrid III dummy were used to evaluate the subsystem under manufacturer created rollover conditions for a production and roll caged roof structure. The objective of this study was to demonstrate the ability to reproduce the impact environment occurring in rollover crash tests. There are over 26,000 fatalities and serious injuries annually occurring in rollover accidents in the United States. Many of these are to restrained occupants and their head and spinal injuries have been associated with contact with the roof structure. To analyze the crash tests the effects of the system, finite element models were made of rollover crash tests that had been conducted using baseline and modified passenger vehicles and Hybrid III dummies using the defined impact conditions. Neck loads were utilized to validate the model against the test results. The results show that finite element modeling can reproduce the results from rollover crash tests.

Coefficient of Restitution Testing: Explicit Finite Element Modeling and Experiments

2010 ◽  
Author(s):  
Martin C. Marinack ◽  
Brian G. Gaudio ◽  
Richard E. Musgrave ◽  
Christopher E. Rizzo ◽  
Michael Lovell ◽  
...  
Keyword(s):  
Finite Element ◽  
Finite Element Modeling ◽  
Tungsten Carbide ◽  
Coefficient Of Restitution ◽  
Experimental Results ◽  
Explicit Finite Element ◽  
Element Modeling ◽  
Chrome Steel ◽  
The Impact ◽  
Element Method

Particle based modeling approaches, such as the discrete element method (DEM) approach, require the definition of accurate contact (collision) models. An essential parameter within these models is the coefficient of restitution (e), which defines the ratio of post-collision to pre-collision relative velocity during the collision of two materials. In this study, e of various steel-material combinations is predicted through both physical experiments and explicit finite element modeling of a falling sphere colliding with a stationary plate, and examined against a theoretical formulation of e. Experiments are performed on various sphere materials including steel, brass, chrome steel, tungsten carbide, aluminum, polybutadiene, and nitinol 60, Experimental results for metals colliding with steel, match what is predicted by theory, as they show a decreasing trend in e with increasing impact velocities. Additional experimental results for polybutadiene rubber show no velocity dependence, remaining constant across the impact velocities examined; this matches with theory. Modeling results, obtained via the explicit finite element method (FEM) approach, are compared against experimental results for verification. Current explicit FEM results show very good quantitative agreement with experimental results for various materials (brass, steel, tungsten carbide, and chrome steel) impacting steel, but do not display the proper decreasing trend in e for increasing impact velocity, over the range of impact velocities examined (∼2 m/s–3.2 m/s). However, for simulations at impact velocities above this range, a decrease in e is witnessed. Current and future work focuses on refining the models to correctly display this qualitative trend within the current range of experimental impact velocities, as well as performing experiments on a wider range of impact velocities.

The impact of boundary conditions and mesh size on the accuracy of cancellous bone tissue modulus determination using large-scale finite-element modeling

1999 ◽  
Vol 32 (11) ◽  
pp. 1159-1164 ◽  
Author(s):  
C.R Jacobs ◽  
B.R Davis ◽  
C.J Rieger ◽  
J.J Francis ◽  
M Saad ◽  
...  
Keyword(s):  
Finite Element ◽  
Boundary Conditions ◽  
Finite Element Modeling ◽  
Bone Tissue ◽  
Cancellous Bone ◽  
Large Scale ◽  
Mesh Size ◽  
Element Modeling ◽  
Tissue Modulus ◽  
The Impact
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