503 A Continuous Measurement of Stress-Strain Curve Using Time Histories of Deformation and External Force by Single Taylor Impact Test

2015 ◽  
Vol 2015.23 (0) ◽  
pp. _503-1_-_503-3_
Author(s):  
Fumiaki IWASAKI ◽  
Takeshi IWAMOTO
Keyword(s):  
External Force ◽  
Impact Test ◽  
Continuous Measurement ◽  
Strain Curve ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Time Histories ◽  
Taylor Impact ◽  
Taylor Impact Test

scholarly journals Finite Element Analysis on a Newly-Modified Method for the Taylor Impact Test to Measure the Stress-Strain Curve by the Only Single Test Using Pure Aluminum

Metals ◽  
2018 ◽  
Vol 8 (8) ◽  
pp. 642 ◽  
Author(s):  
Chong Gao ◽  
Takeshi Iwamoto
Keyword(s):  
Finite Element ◽  
Impact Test ◽  
Pure Aluminum ◽  
Strain Curve ◽  
Hopkinson Pressure Bar ◽  
Stress Strain ◽  
Hardening Law ◽  
Taylor Impact ◽  
Taylor Impact Test ◽  
Pressure Bar

In this study, finite element analyses are performed to obtain a stress-strain curve for ductile materials by a combination between the distributions of axial stress and strain at a certain time as a result of one single Taylor impact test. In the modified Taylor impact test proposed here, a measurement of the external impact force by the Hopkinson pressure bar placed instead of the rigid wall, and an assumption of bi-linear distribution of an axial internal force, are introduced as well as a measurement of deformed profiles at certain time. In order to obtain the realistic results by computations, at first, the parameters in a nonlinear rate sensitive hardening law are identified from the quasi-static and impact tests of pure aluminum at various strain rates and temperature conducted. In the impact test, a miniaturized testing apparatus based on the split Hopkinson pressure bar (SHPB) technique is introduced to achieve a similar level of strain rate as 104 s−1, to the Taylor test. Then, a finite element simulation of the modified test is performed using a commercial software by using the user-subroutine for the hardening law with the identified parameters. By comparing the stress-strain curves obtained by the proposed method and direct calculation of the hardening law, the validity is discussed. Finally, the feasibility of the proposed method is studied.

scholarly journals Can-Crush Model and Simulations for Verifying Uncertainty Quantification Method for Sparse Stress-Strain Curve Data

2016 ◽  
Author(s):  
J. F. Dempsey ◽  
V. Romero ◽  
N. Breivik ◽  
G. Orient ◽  
B. Antoun ◽  
...  
Keyword(s):  
Strain Curve ◽  
Element Model ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Response Variance ◽  
Highly Nonlinear ◽  
Time Histories ◽  
Standard Response ◽  
Ductile Steel ◽  
Weld Time

This work examines the variability of predicted responses when multiple stress-strain curves (reflecting variability from replicate material tests) are propagated through a transient dynamics finite element model of a ductile steel can being slowly crushed. An elastic-plastic constitutive model is employed in the large-deformation simulations. The present work assigns the same material to all the can parts: lids, walls, and weld. Time histories of 18 response quantities of interest (including displacements, stresses, strains, and calculated measures of material damage) at several locations on the can and various points in time are monitored in the simulations. Each response quantity’s behavior varies according to the particular stress-strain curves used for the materials in the model. We estimate response variability due to variability of the input material curves. When only a few stress-strain curves are available from material testing, response variance will usually be significantly underestimated. This is undesirable for many engineering purposes. This paper describes the can-crush model and simulations used to evaluate a simple classical statistical method, Tolerance Intervals (TIs), for effectively compensating for sparse stress-strain curve data in the can-crush problem. Using the simulation results presented here, the accuracy and reliability of the TI method are being evaluated on the highly nonlinear input-to-output response mappings and non-standard response distributions in the can-crush UQ problem.

Verification of Taylor Impact Test by Using Force Sensing Block

2014 ◽  
Vol 626 ◽  
pp. 444-449
Author(s):  
Fumiaki Iwasaki ◽  
Nobuhiko Kii ◽  
Takeshi Iwamoto
Keyword(s):  
Strain Rate ◽  
External Force ◽  
Impact Test ◽  
Split Hopkinson Pressure Bar ◽  
Time History ◽  
Rigid Wall ◽  
Force Sensing ◽  
Past Study ◽  
Taylor Impact ◽  
Taylor Impact Test

In the Taylor impact test, obtained strain rate becomes in a range of 103~105/s corresponding to penetration of space debris to a space structure. According to this test, a stress value can be calculated by theoretical formulae. However, the formulae include some assumptions and the external force acting on a specimen is not directly measured by using the formulae. In the past study, the split Hopkinson pressure bar (SHPB) is employed instead of a use of a rigid wall which the specimen collides. However, there are two difficulties on this method. The first one is to be a similar range of measurable strain rate to the SHPB technique and the second is to require a sufficiently-large space for a testing apparatus. In contrast, by introducing a force sensing block, the apparatus becomes compact and longer measurable time is realized compared with the SHPB technique. Therefore, the stress value can be measured with higher precision since an extensive range of strain rate can be measurable. In this study, to enhance the precision of the test, it is suggested that the force sensing block is placed just behind the rigid wall for a direct measurement of a time history of external force.

A modified version of MATLAB application window for predicting the weld bead profile and stress–strain plot of AA5052 CMT weldment using ER4043

SIMULATION ◽  
2021 ◽  
pp. 003754972110315
Author(s):  
B Girinath ◽  
N Siva Shanmugam
Keyword(s):  
Strain Curve ◽  
Weld Bead ◽  
Welding Parameters ◽  
Bead Geometry ◽  
Hybrid Technique ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Weld Bead Geometry ◽  
Inference System ◽  
Engineering Stress

The present study deals with the extended version of our previous research work. In this article, for predicting the entire weld bead geometry and engineering stress–strain curve of the cold metal transfer (CMT) weldment, a MATLAB based application window (second version) is developed with certain modifications. In the first version, for predicting the entire weld bead geometry, apart from weld bead characteristics, x and y coordinates (24 from each) of the extracted points are considered. Finally, in the first version, 53 output values (five for weld bead characteristics and 48 for x and y coordinates) are predicted using both multiple regression analysis (MRA) and adaptive neuro fuzzy inference system (ANFIS) technique to get an idea related to the complete weld bead geometry without performing the actual welding process. The obtained weld bead shapes using both the techniques are compared with the experimentally obtained bead shapes. Based on the results obtained from the first version and the knowledge acquired from literature, the complete shape of weld bead obtained using ANFIS is in good agreement with the experimentally obtained weld bead shape. This motivated us to adopt a hybrid technique known as ANFIS (combined artificial neural network and fuzzy features) alone in this paper for predicting the weld bead shape and engineering stress–strain curve of the welded joint. In the present study, an attempt is made to evaluate the accuracy of the prediction when the number of trials is reduced to half and increasing the number of data points from the macrograph to twice. Complete weld bead geometry and the engineering stress–strain curves were predicted against the input welding parameters (welding current and welding speed), fed by the user in the MATLAB application window. Finally, the entire weld bead geometries were predicted by both the first and the second version are compared and validated with the experimentally obtained weld bead shapes. The similar procedure was followed for predicting the engineering stress–strain curve to compare with experimental outcomes.

Stress-strain curve of paper revisited

2012 ◽  
Vol 27 (2) ◽  
pp. 318-328 ◽  
Author(s):  
Svetlana Borodulina ◽  
Artem Kulachenko ◽  
Mikael Nygårds ◽  
Sylvain Galland
Keyword(s):  
Three Dimensional ◽  
Strain Curve ◽  
Failure Behavior ◽  
Three Dimensional Model ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Fiber Network ◽  
Bonding Parameters ◽  
Particle Level ◽  
The Impact

Abstract We have investigated a relation between micromechanical processes and the stress-strain curve of a dry fiber network during tensile loading. By using a detailed particle-level simulation tool we investigate, among other things, the impact of “non-traditional” bonding parameters, such as compliance of bonding regions, work of separation and the actual number of effective bonds. This is probably the first three-dimensional model which is capable of simulating the fracture process of paper accounting for nonlinearities at the fiber level and bond failures. The failure behavior of the network considered in the study could be changed significantly by relatively small changes in bond strength, as compared to the scatter in bonding data found in the literature. We have identified that compliance of the bonding regions has a significant impact on network strength. By comparing networks with weak and strong bonds, we concluded that large local strains are the precursors of bond failures and not the other way around.

Definition of the yield point in plasticity and its effect on the shape of the yield locus

1966 ◽  
Vol 1 (4) ◽  
pp. 331-338 ◽  
Author(s):  
T C Hsu
Keyword(s):  
Yield Point ◽  
Experimental Work ◽  
Strain Curve ◽  
Yield Locus ◽  
Experimental Results ◽  
Stress Strain Curve ◽  
Proportional Limit ◽  
Stress Strain ◽  
Small Section ◽  
Definition Of

Three different definitions of the yield point have been used in experimental work on the yield locus: proportional limit, proof strain and the ‘yield point’ by backward extrapolation. The theoretical implications of the ‘yield point’ by backward extrapolation are examined in an analysis of the loading and re-loading stress paths. It is shown, in connection with experimental results by Miastkowski and Szczepinski, that the proportional limit found by inspection is in fact a point located by backward extrapolation based on a small section of the stress-strain curve, near the elastic portion of the curve. The effect of different definitions of the yield point on the shape of the yield locus and some considerations for the choice between them are discussed.

Identification of post-necking stress–strain curve for sheet metals by inverse method

2016 ◽  
Vol 92 ◽  
pp. 107-118 ◽  
Author(s):  
Kunmin Zhao ◽  
Limin Wang ◽  
Ying Chang ◽  
Jianwen Yan
Keyword(s):  
Inverse Method ◽  
Strain Curve ◽  
Sheet Metals ◽  
Stress Strain Curve ◽  
Stress Strain
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