Multi-scale structure finite element analyses of damage behaviors of multi-axial warp-knitted composite materials subjected to quasi-static and high strain rate compressions

2015 ◽  
Vol 107 (7) ◽  
pp. 879-904 ◽  
Author(s):  
Yumin Wan ◽  
Baozhong Sun ◽  
Bohong Gu
Keyword(s):  
Finite Element ◽  
Composite Materials ◽  
High Strain Rate ◽  
Strain Rate ◽  
High Strain ◽  
Scale Structure ◽  
Finite Element Analyses ◽  
Multi Scale

An Alternate Approach to SHPB Tests to Compute Johnson-Cook Material Model Constants for 97 WHA at High Strain Rates and Elevated Temperatures Using Machining Tests

2020 ◽  
Vol 143 (2) ◽  
Author(s):  
Chithajalu Kiran Sagar ◽  
Amrita Priyadarshini ◽  
Amit Kumar Gupta ◽  
Tarun Kumar ◽  
Shreya Saxena
Keyword(s):  
Finite Element ◽  
High Strain Rate ◽  
Strain Rate ◽  
Elevated Temperatures ◽  
High Strain ◽  
Optimization Technique ◽  
Material Model ◽  
Computational Techniques ◽  
Fe Model

Abstract With advances in computational techniques, numerical methods such as finite element method (FEM) are gaining much of the popularity for analysis as these substitute the expensive trial and error experimental techniques to a great extent. Consequently, selection of suitable material models and determination of precise material model constants are one of the prime concerns in FEM. This paper presents a methodology to determine the Johnson-Cook constitutive equation constants (JC constants) of 97 W Tungsten heavy alloys (WHAs) under high strain rate conditions using machining tests in conjunction with Oxley’s predictive model and particle swarm optimization (PSO) algorithm. Currently, availability of the high strain rate data for 97 WHA are limited and consequently, JC constants for the same are not readily available. The overall methodology includes determination of three sets of JC constants, namely, M1 and M2 from the Split-Hopkinson pressure bar (SHPB) test data available in literature by using conventional optimization technique and artificial bee colony (ABC) algorithm, respectively. However, M3 is determined from machining tests using inverse identification method. To validate the identified JC constants, machining outputs (cutting forces, temperature, and shear strain) are predicted using finite element (FE) model by considering M1, M2, and M3 as input under different cutting conditions and then validated with corresponding experimental values. The predicted outputs obtained using JC constants M3 closely matched with that of the experimental ones with error percentage well within 10%.

scholarly journals FE Analysis of Critical Testing Parameters in Kolsky Bar Experiments for Elastomers at High Strain Rate

Materials ◽  
2019 ◽  
Vol 12 (23) ◽  
pp. 3817
Author(s):  
Chaudhry ◽  
Czekanski
Keyword(s):  
Finite Element ◽  
High Strain Rate ◽  
Strain Rate ◽  
Pulse Shaping ◽  
High Strain ◽  
Kolsky Bar ◽  
Specimen Geometry ◽  
Strain Rates ◽  
Butadiene Rubber ◽  
Testing Apparatus

The main aim of this research is to present complete methodological guidelines for dynamic characterization of elastomers when subjected to strain rates of 100/s–10,000/s. We consider the following three aspects: (i) the design of high strain rate testing apparatus, (ii) finite element analysis for the optimization of the experimental setup, and (iii) experimental parameters and validation for the response of an elastomeric specimen. To test low impedance soft materials, design of a modified Kolsky bar is discussed. Based on this design, the testing apparatus was constructed, validated, and optimized numerically using finite element methods. Furthermore, investigations on traditional pulse shaping techniques and a new design for pulse shaper are described. The effect of specimen geometry on the homogeneous deformation has been thoroughly accounted for. Using the optimized specimen geometry and pulse shaping technique, nitrile butadiene rubber was tested at different strain rates, and the experimental findings were compared to numerical predictions.

SIF Evaluation Using XFEM and Line Spring Models Under High Strain Rate Environment for Leadfree Alloys

2011 ◽  
Author(s):  
Pradeep Lall ◽  
Mandar Kulkarni ◽  
Sandeep Shantaram ◽  
Jeff Suhling
Keyword(s):  
Stress Intensity Factor ◽  
Finite Element ◽  
Stress Intensity ◽  
Intensity Factor ◽  
High Strain Rate ◽  
Strain Rate ◽  
High Speed ◽  
High Strain ◽  
Strain Rates ◽  
Fracture Properties

In this paper, fracture properties of Sn3Ag0.5Cu leadfree high strain-rate solder-copper interface have been evaluated and validated with those from experimental methods. Bi-material Copper-Solder specimen have been tested at strain rates typical of shock and vibration with impact-hammer tensile testing machine. Models for crack initiation and propagation have been developed using Line spring method and extended finite element method (XFEM). Critical stress intensity factor for Sn3Ag0.5Cu solder-copper interface have been extracted from line spring models. Displacements and derivatives of displacements have been measured at crack tip and near interface of bi-material specimen using high speed imaging in conjunction with digital image correlation. Specimens have been tested at strain rates of 20s−1 and 55s−1 and the event is monitored using high speed data acquisition system as well as high speed cameras with frame rates in the neighborhood of 300,000 fps. Previously the authors have applied the technique of XFEM and DIC for predicting failure location and to develop constitutive models in leaded and few leadfree solder alloys [Lall 2010a]. The measured fracture properties have been applied to prediction of failure in ball-grid arrays subjected to high-g shock loading in the neighborhood of 12500g in JEDEC configuration. Prediction of fracture in board assemblies using explicit finite element full-field models of board assemblies under transient-shock is new. Stress intensity factor at Copper pad and bulk solder interface is also evaluated in ball grid array packages.

Modified Quartet Structure Generation Set Reconstruction of Finite Element Model for Co-Continuous Ceramic Composites

2015 ◽  
Vol 782 ◽  
pp. 278-290 ◽  
Author(s):  
Qing Xiang Wang ◽  
Hong Mei Zhang ◽  
Hong Nian Cai ◽  
Qun Bo Fan
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
High Strain Rate ◽  
Strain Rate ◽  
High Strain ◽  
Volume Fraction ◽  
Element Model ◽  
Ceramic Composites ◽  
Structure Generation ◽  
Sem Image

Co-continuous ceramic composites have a complicated topology structure which makes it much more difficult for finite element model reconstruction. In this paper, the two-dimensional co-continuous ceramic composites finite element model is reconstructed by a modified quartet structure generation set method which modified the generation parameters based on quartet structure generation set (QSGS) method, and a numerical simulation at high strain rate is accomplished. The content mainly contains: (1) The distribution features of metal phase and ceramic phase of real co-continuous ceramic composites SEM image is calculated by mathematical statistics to determine the parameters that control the reconstruction such as volume fraction, core distribution probability and directional growth probability; (2) Two phase volume fraction and 2-point correlation function of the reconstructed finite element model is calculated as the quality assessment parameters, which verify the reconstructed finite element model are in allowable error range compared with the real SEM image; (3) Numerical simulation at high strain rate is carried out using the reconstructed finite element model. The failure behavior of co-continuous ceramic composites at high strain rate is analyzed, validates the reconstructed finite element model meets the requirements of numerical calculation.

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