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Grenade, France
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Jadhav N.,Ford Motor Company | Zhao L.,Ford Motor Company | Mahadevan S.,Ford Motor Company | Sherwood B.,Ford Motor Company | And 2 more authors.
SAE Technical Papers | Year: 2017

The Pelvis-Thorax Side Air Bag (PTSAB) is a typical restraint countermeasure offered for protection of occupants in the vehicle during side impact tests. Currently, the dynamic performance of PTSAB for occupant injury assessment in side impact is limited to full-vehicle evaluation and sled testing, with limited capability in computer aided engineering (CAE). The widely used CAE method for PTSAB is a flat bag with uniform pressure. The flat PTSAB model with uniform pressure has limitations because of its inability to capture airbag deployment during gap closure which results in reduced accuracy while predicting occupant responses. Hence there is a need to develop CAE capability to enhance the accuracy of prediction of occupant responses to meet performance targets in regulatory and public domain side impact tests. This paper describes a new CAE methodology for assessment of PTSAB in side impact. This method was developed and validated to component and full-vehicle tests, and was successfully used to guide the design and development of PTSAB. The bag was folded using simulation folding developed by LSTC. A particle method (Computational Fluid Dynamics) in LS-DYNA® was used to deploy the PTSAB. The PTSAB model was correlated at a component level using linear impact test, and force-deflection plots of the CAE model were matched with that of the test. The PTSAB model was then implemented in a full vehicle simulation. The key factors that play a role in correlating the model and its ability to predict the test results are discussed in this paper. © 2017 SAE International.


Gandikota R.,MindMesh Inc. | Nair A.,LSTC | Miller K.,Axel Products Inc.
SAE Technical Papers | Year: 2017

Testing elastomeric materials that undergo large strains pose challenges especially when establishing failure criteria. The failure criterion for composites and polymers based on finite elasticity published by Feng (1) requires testing under uniaxial and biaxial stretching modes. The classic inflation of a circular disk for biaxial stretch mode poses stability and safety challenges. The test can also be sensitive to end constraints resulting in failure of materials at the constraints. Biaxial stretching with a hemispherical punch is explored in this work. The biaxial stretching allows controlled and repeatable testing. It establishes a clear and reliable failure mechanism of the material at the poles. Through a combination of testing and numerical methods, the stretch ratios and its relation to failure have been established. The method greatly simplifies testing and provides reliable data for a failure criterion for elastomers in numerical modeling. Copyright © 2017 SAE International.


Langlet A.,University of Orléans | Souli M.,French National Center for Scientific Research | Aquelet N.,LSTC | Pennetier O.,University of Orléans | Girault G.,Ecoles de Saint-Cyr Coetquidan
Shock Waves | Year: 2015

In this paper, the Multi-Material ALE formulation is applied to simulate the propagation of an air blast through the atmosphere, and its reflection on an assumed rigid cylindrical obstacle. The mathematical and numerical implementations of this formulation are presented. In order to validate the formulation and prove its ability to capture the propagation and reflection of high pressure waves, comparisons of the simulations with the experimental blast pressure measured on an assumed rigid cylinder are performed. The simulation conducted via the presented models and methods gives good predictions for pressure time histories recorded on the rigid cylinder. © 2014, Springer-Verlag Berlin Heidelberg.


Hoffarth C.,Arizona State University | Rajan S.D.,Arizona State University | Goldberg R.K.,NASA | Revilock D.,NASA | And 3 more authors.
Composites Part A: Applied Science and Manufacturing | Year: 2016

A new orthotropic elasto-plastic constitutive model has been developed to predict the inelastic response of composite materials under high velocity impact conditions. The model is driven by experimental stress-strain curve data stored as tabular input allowing for a very general material description. The theoretical details of the elasto-plastic deformation part of the material model are briefly summarized. This summary is then followed by details of the numerical implementation of the model as MAT213 (suitable for use with solid elements) into the commercial transient dynamic finite element code, LS-DYNA. The theoretical basis and the numerical implementation of the constitutive model are validated by using two sets of validation tests involving a widely used unidirectional composite, T800/F3900 - composite laminates used in coupon level tests and a low velocity impact test on a flat panel. Results show that the implementation is efficient, robust and accurate. © 2016 Elsevier Ltd


Limido J.,IMPETUS Advanced Finite Element Analysis | Espinosa C.,INSA Toulouse | Salaun M.,INSA Toulouse | Mabru C.,INSA Toulouse | And 2 more authors.
International Journal of Machining and Machinability of Materials | Year: 2011

The purpose of this work is to evaluate the use of the smoothed particle hydrodynamics (SPH) method within the framework of high speed cutting modelling. First, a 2D SPH based model is carried out using the LS-DYNA® software. The developed SPH model proves its ability to account for continuous and shear localised chip formation and also correctly estimates the cutting forces, as illustrated in some orthogonal cutting examples. Then, the SPH model is used in order to improve the general understanding of machining with worn tools. At last, a hybrid milling model allowing the calculation of the 3D cutting forces is presented. The interest of the suggested approach is to be freed from classically needed machining tests: Those are replaced by 2D numerical tests using the SPH model. The developed approach proved its ability to model the 3D cutting forces in ball end milling. Copyright © 2011 Inderscience Enterprises Ltd.


Tyan T.,Ford Motor Company | McClain B.,Ford Motor Company | Arthurs K.D.,Ford Motor Company | Rupp J.,Ford Motor Company | And 5 more authors.
SAE International Journal of Materials and Manufacturing | Year: 2012

An Arbitrary Lagrangian Eulerian (ALE) approach was adopted in this study to predict the responses of side crash pressure sensors in an attempt to assist pressure sensor algorithm development by using computer simulations. Acceleration-based crash sensors have traditionally been used to deploy restraint devises (e.g., airbags, air curtains, and seat belts) in vehicle crashes. The crash pulses recorded by acceleration-based crash sensors usually exhibit high frequency and noisy responses depending on the vehicle's structural design. As a result, it is very challenging to predict the responses of acceleration-based crash sensors by using computer simulations, especially those installed in crush zones. Therefore, the sensor algorithm developments for acceleration-based sensors are mostly based on physical testing. With the advancement in the crash sensor technology, pressure sensors that detect pressure change in door cavities have been developed recently and production vehicle applications are increasing. The pressure sensors detect pressure change when there is a change in the door volume. Due to the nature of pressure change, the data obtained from side crash pressure sensors exhibits lower frequency and less noisy responses which are quite different from those of the acceleration-based crash sensors. The technology is most promising for side crash applications due to its ability to discriminate crash severities and deploy airbags earlier. The lower frequency and less noisy responses are also more suitable for non-linear finite element codes to predict. To help understand the responses of pressure sensors and obtain reliable test data for model developments, fourteen different benchmark tests were designed and performed in this research. The first set of benchmark tests included a rectangular steel container with one side being compressed while all other sides were fixed to simulate a piston compression condition. The second set of benchmark tests, a series of eight, involved a rigid impactor or a deformable barrier hitting a rectangular steel box with and without a hole. Different speeds were chosen in the second set of component tests to obtain the corresponding responses. The third set of benchmark tests, a series of five, involved a rigid impactor or a deformable barrier hitting a vehicle side door with different openings. Similar to the second set of the benchmark tests; different speeds were chosen to create different crash severities. Computer simulations for all fourteen benchmark tests were conducted by employing the ALE method as one of the studies in this research. The results obtained from the benchmark tests and the computer simulations are presented and discussed in this paper. © 2012 SAE International.


Tyan T.,Ford Motor Company | McClain B.,Ford Motor Company | Arthurs K.,Ford Motor Company | Rupp J.,Ford Motor Company | And 5 more authors.
SAE International Journal of Materials and Manufacturing | Year: 2012

In an attempt to predict the responses of side crash pressure sensors, the Corpuscular Particle Method (CPM) was adopted and enhanced in this research. Acceleration-based crash sensors have traditionally been used extensively in automotive industry to determine the air bag firing time in the event of a vehicle accident. The prediction of crash pulses obtained from the acceleration-based crash sensors by using computer simulations has been very challenging due to the high frequency and noisy responses obtained from the sensors, especially those installed in crash zones. As a result, the sensor algorithm developments for acceleration-based sensors are largely based on prototype testing. With the latest advancement in the crash sensor technology, side crash pressure sensors have emerged recently and are gradually replacing acceleration-based sensor for side impact applications. Unlike the acceleration-based crash sensors, the data recorded by the side crash pressure sensors exhibits lower frequency and less noisy responses which is more conductive for CAE prediction. In the attempt to predict the side crash pressure sensor responses, fourteen different benchmark tests were designed and conducted to provide data for model validations. The fourteen benchmark tests can be divided into three sets based on the structure designs. The first set of benchmark tests included a rectangular rigid container with one side being compressed while all other sides were fixed to simulate a piston compression condition. The second set of benchmark tests contained a rigid impactor or a deformable barrier hitting a rectangular steel box with and without a hole. Different speeds were chosen in the second set of benchmark tests to obtain the corresponding pressure responses. The third set of benchmark tests involved a rigid impactor or a deformable barrier hitting a real vehicle side door with different openings. In the baseline door test, the window weather strip and speaker were kept and all holes in door inner were closed to represent a production door. To ensure the robustness of CAE predictions for different door designs, the window weather strip was removed and some holes in the door inner were opened in some of the door benchmark tests. Computer models were created according to the corresponding test conditions. The CPM method originally developed in LS-DYNA to simulate the deployments of side air bags and side air curtains was adopted and improved in this research to predict the responses of the side crash pressure sensors. One of the main purposes of adopting such method in this project is trying to expand the application of the CPM method to problems that do not involve inflators. With major improvements in the CPM method through this research in the past two years, not only the responses of side crash pressure sensor can be predicted but also the computation time required to complete such simulations has been shortened. The development of the modeling methodology to predict the responses of the side crash pressure sensors will also make it possible to use computer simulations as part of side crash sensor development and results in more robust sensor firing algorithm. © 2012 SAE International.

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