Quasi-Static and Dynamic Characterization of Oil-Based Modeling Clay and Numerical Simulation of Drop-Impact Test

2011 ◽  
Author(s):  
C. Hernandez ◽  
A. Maranon ◽  
I. A. Ashcroft ◽  
J. P. Casas-Rodriguez
Keyword(s):  
Numerical Simulation ◽  
High Strain Rate ◽  
Strain Rate ◽  
Impact Test ◽  
High Strain ◽  
Material Model ◽  
Drop Impact ◽  
Material Constants ◽  
Drop Impact Test ◽  
Modeling Clay

Numerical simulations require the determination of material constants associated to a given mathematical material model that accurately represents its mechanical behavior. Furthermore, for dynamic models, the characterization process should be accomplished at high strain rates since the mechanical properties of some materials are influenced by the rate of loading. This pressure-dependant behavior is commonly seen in paste-like materials such as oil-based modeling clay. This material, is widely used as simulating a material for analyzing metal forming processes, in impact applications as soft body impactor, or as backing material in ballistic resistance testing of body armors. There are many techniques used for characterizing these kinds of pastelike materials. Traditional quasi-static tests, such as compression or indentation, are the most commonly used, although, high strain rate techniques, such as the drop-impact test, are also used when dynamic properties are required. This paper presents the mechanical characterization of an oil-based modeling clay by two different techniques: quasi-static and a high strain rate technique. The results of a traditional quasi-static method, using compression tests, are compared with the constants determined by a proposed high strain rate characterization procedure that uses as input a single drop-impact test. Both sets of material constants are implemented in a numerical simulation that uses the power law plasticity material model. Drop impact numerical simulations and their verification against experimental results were performed to compare the accuracy of both sets of material constants and the suitability of the characterization techniques. Results illustrate that the proposed high strain rate characterization technique show advantages in the determination of the materials constants for the numerical simulation of dynamic events.

Numerical Simulation of Hot High Strain Rate Torsion Tests for Al-Based Alloys

2019 ◽  
Vol 822 ◽  
pp. 66-71
Author(s):  
Anton Naumov ◽  
Anatolii Borisov ◽  
Anastasiya Y. Doroshchenkova
Keyword(s):  
Numerical Simulation ◽  
High Strain Rate ◽  
Strain Rate ◽  
Visual Analysis ◽  
Physical Simulation ◽  
High Strain ◽  
Torsion Test ◽  
Strain Rates ◽  
Deform 3D

The present research describes the comparison of numerical and physical simulation of hot high strain rate torsion tests for Al-based alloys in order to clarify the accuracy of calculations using basic grades of materials in Deform-3DTM software. A comparative visual analysis of the results is presented. Obtained data on the distribution of temperatures, strains, stresses and strain rates during the torsion test are discussed.

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%.

Influence of Temperature on Dynamic Behavior of Rubber Materials by Taylor Impact Test

2011 ◽  
Vol 673 ◽  
pp. 83-88 ◽  
Author(s):  
Hyung Seop Shin ◽  
Sung Su Park ◽  
Joon Hong Choi
Keyword(s):  
High Strain Rate ◽  
Strain Rate ◽  
Deformation Behavior ◽  
High Speed ◽  
Impact Test ◽  
High Strain ◽  
High Speed Photography ◽  
Impact Tests ◽  
Taylor Impact ◽  
Taylor Impact Test

The understanding of the deformation behavior of rubber materials under high strain-rate or high loading-rate conditions will be important in their impact applications adopting significant viscoelastic behavior. Taylor impact test has originally used to determine the average dynamic yield strength of metallic materials at high strain rates, but it also can be used to examine the overall deformation behavior of rubbers representing large elastic deformation by using a high-speed photography technique. Taylor impact tests of rubber materials were carried out in the velocity range between 100~250 m/s using a 20 mm air gun. In order to investigate the overall dynamic deformation behavior of rubber projectiles during Taylor impact test, a 8-Ch high-speed photography system which provides a series of images at each elapsed time was incorporated. Three kinds of rubber materials with different Tg (glass transition temperature) were supplied. The bulging behavior of rubber projectile could be evaluated quantitatively by digitizing images taken. Taylor impact tests at various temperature levels were conducted to predict the bulging behavior of rubbers at high strain rate.

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