scholarly journals Homogeneous Metal Foam Manufacturing and Impact Test Performance

2019 ◽  
Vol 15 (8) ◽  
pp. 2040
Author(s):  
Kaimal Ananthakrishnan ◽  
Boban Mathew Bevin ◽  
Jeyanthi S.
Keyword(s):  
Test Performance ◽  
Impact Test ◽  
Metal Foam

EFFECT OF RELATIVE DENSITY AND VELOCITY TOWARDS DYNAMIC RESPONSE OF METAL FOAM

2015 ◽  
Vol 76 (9) ◽  
Author(s):  
Mohd Azman Y. ◽  
Juri S. ◽  
Hazran H. ◽  
NorHafiez M. N. ◽  
Dong R.
Keyword(s):  
Finite Element ◽  
Dynamic Response ◽  
Theoretical Prediction ◽  
Relative Density ◽  
Impact Velocity ◽  
Impact Test ◽  
Metal Foam ◽  
Element Analysis ◽  
Static Tests ◽  
The Impact

Dynamic response of ALPORAS aluminium foam has been investigated experimentally and numerically. The dynamic response is quantified by the force produced as the foam deforms as a function of time. Quasi-static tests are conducted to determine the quasi-static properties of the foam. In the impact test, the aluminium foams are fired towards a rigid load-cell and the force signals developed are recorded. Experimental dynamic stress is also compared with theoretical prediction using existing theory. Finite element model is constructed using LS-DYNA to simulate the impact test. Results from the experiment, finite element analysis and theoretical prediction are in acceptable agreement. Finally, parametric studies have been conducted using the verified model to investigate the effect of impact velocity and relative density towards the dynamic response of the foam projectile. It is found that the dynamic response of the foam is more sensitive towards impact velocity as compare with the foam relative density.

scholarly journals Comparison of test performance on paper-based testing (PBT) and computer-based testing (CBT) by English-majored undergraduate students in China

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Wenjing Yu ◽  
Noriko Iwashita
Keyword(s):  
Undergraduate Students ◽  
Mixed Method ◽  
Test Performance ◽  
Impact Test ◽  
Comfort Level ◽  
Proficiency Tests ◽  
Structured Interviews ◽  
Computer Based ◽  
Computer Based Testing ◽  
Testing Mode

AbstractComputer-based testing (CBT), which refers to delivering assessments with computers, has been widely used in large English proficiency tests worldwide. Despite an increasing CBT in China, limited research is available concerning whether CBT can be used for the Test for English Majors-Band 4 (TEM 4). The current study investigated whether testing mode impacted TEM 4 score and factors (i.e., computer familiarity level and attitude towards CBT) that might correlate with performance on CBT of TEM 4. Overall 92 Chinese undergraduate students were randomly assigned to one of the groups, i.e., CBT or paper-based testing (PBT), and took the test. A mixed method was employed, including (1) quantitative and qualitative analysis of test performance in two modes, as well as CBT group participants’ computer familiarity and attitudes towards the mode; and (2) thematic analysis of semi-structured interviews. The results revealed that (1) test scores in CBT and PBT were comparable; (2) two items in the computer familiarity questionnaire, i.e., comfort level of reading articles on the computer and forgetting time when using computers, positively correlated with CBT scores; and (3) participants’ attitude towards CBT did not impact test performance.

scholarly journals Modified Falling Mass Impact Test Performance on Functionally Graded Two Stage Aggregate Fibrous Concrete

Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5833
Author(s):  
Nandhu Prasad ◽  
Gunasekaran Murali ◽  
Nikolai Vatin
Keyword(s):  
Test Performance ◽  
Impact Test ◽  
Impact Resistance ◽  
American Concrete Institute ◽  
Functionally Graded ◽  
Test Results ◽  
Two Stage ◽  
Polypropylene Fibres ◽  
Fibre Composites ◽  
Fibrous Concrete

This research examined the performance of functionally graded two-stage fibrous concrete (FTSFC) against modified repeated falling-mass impacts. This study led to the concept of creating improved multiphysics model of fibre composites with better impact resistance for potential protective constructions. FTSFC was developed based on the bio-inspiring strength of turtle shells. The excellent impact resistance of FTSFC was accomplished by including a larger quantity of steel and polypropylene fibres in the outer layers. At the same time, one- and two-layered concrete were cast and compared to evaluate the efficiency of three-layered FTSFC. To minimize the dispersed test results, a modified form of the 544 drop-mass impact test was recommended by the American Concrete Institute (ACI). The modification was a knife-edge notched specimen instead of a solid cylindrical specimen without a notch. This modification predefined a crack path and reduced the dispersion of results. Cracking and failure impact numbers, ductility index, and failure mode were the testing criteria. The suggested modification to the ACI impact test decreased the coefficient of variance, showing that the dispersion of test results was reduced significantly. This study led to the concept of creating improved, fibre composites with better impact resistance for potential protective constructions.

Impact test performance of Zn-based die-attach joints for power devices

2012 ◽  
Author(s):  
Jenn-Ming Song ◽  
Meng-Ju Lin ◽  
Yi-Shao Lai ◽  
Ying-Ta Chiu
Keyword(s):  
Test Performance ◽  
Impact Test ◽  
Power Devices ◽  
Die Attach
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