Quick Evaluation of Crashworthiness for Nonlinear Damped Systems by Using an Analytical Linearization Method

2005 ◽  
Author(s):  
Yuqi Wang ◽  
K. H. Low
Keyword(s):  
Nonlinear Analysis ◽  
Impact Loading ◽  
Linearization Method ◽  
Drop Impact ◽  
Accurate Analysis ◽  
Good Efficiency ◽  
Reliability Design ◽  
Damped Systems ◽  
The Impact ◽  
Analytical Approaches

The ability to predict crashworthiness is helpful for the cushion design. This is to minimize the impact loading on packaged products, such as drop impact loading occurring during shipment or transportation. In addition, the nonlinear characteristic of cushion system would affect the crashworthiness of the packaged goods. Therefore, an accurate analysis for the nonlinear cushion system is crucial in reliability design. However if nonlinear analysis is performed, a large computation load is required for numerical approaches; on the other hand, there is a need to include higher transcendent functions within the analytical approaches. In this paper, an analytical linearization method is applied to obtain quantitative solution in the nonlinear analysis. This method is not a numerical method, meanwhile, no high transcendent functions are considered. Therefore, the crashworthiness for nonlinear drop-impact systems can be quickly evaluated. In practical application, this method also shows good efficiency and good agreement with the experimental results.

A STUDY ON THE BEHAVIOR OF A THIN STS 304 SHEET WITH A FREE BOUNDARY CONDITIONS SUBJECTED TO IMPACT LOADING

2008 ◽  
Vol 22 (31n32) ◽  
pp. 5572-5577 ◽  
Author(s):  
D. G. AHN ◽  
G. J. MOON ◽  
C. G. JUNG ◽  
D. Y. YANG
Keyword(s):  
Free Boundary ◽  
Impact Energy ◽  
Impact Loading ◽  
Three Dimensional ◽  
Local Deformation ◽  
Drop Impact ◽  
Absorption Mechanism ◽  
Impact Tests ◽  
Deformation Behaviors ◽  
The Impact

The objective of this paper is to investigate into impact behaviors of a STS 304 sheet with a thickness of 0.7 mm in a free boundary condition subjected to impact loading by a hemispherical impact head using drop impact tests and the three-dimensional FE analyses. The drop impact tests and the FE analyses were conducted with different impact energy ranging from 37.0 J to 45.7 J. From the results of the impact tests, the influence of the impact energy on the force-deflection curve, the absorption mechanism of the impact energy and deformation behaviors of specimen were examined quantitatively. Through the FE analyses, the variation of stress-strain distributions and characteristics of the local deformation during the impact of the specimen were investigated.

scholarly journals Nonlocal and Size-Dependent Dielectric Function for Plasmonic Nanoparticles

2019 ◽  
Vol 9 (15) ◽  
pp. 3083
Author(s):  
Kai-Jian Huang ◽  
Shui-Jie Qin ◽  
Zheng-Ping Zhang ◽  
Zhao Ding ◽  
Zhong-Chen Bai
Keyword(s):  
Metallic Nanoparticles ◽  
High Efficiency ◽  
Finite Size ◽  
Plasmonic Nanostructures ◽  
Accurate Analysis ◽  
Finite Size Effects ◽  
Size Dependent ◽  
Quantum Size ◽  
The Impact ◽  
Electron Energy Loss

We develop a theoretical approach to investigate the impact that nonlocal and finite-size effects have on the dielectric response of plasmonic nanostructures. Through simulations, comprehensive comparisons of the electron energy loss spectroscopy (EELS) and the optical performance are discussed for a gold spherical dimer system in terms of different dielectric models. Our study offers a paradigm of high efficiency compatible dielectric theoretical framework for accounting the metallic nanoparticles behavior combining local, nonlocal and size-dependent effects in broader energy and size ranges. The results of accurate analysis and simulation for these effects unveil the weight and the evolution of both surface and bulk plasmons vibrational mechanisms, which are important for further understanding the electrodynamics properties of structures at the nanoscale. Particularly, our method can be extended to other plasmonic nanostructures where quantum-size or strongly interacting effects are likely to play an important role.

scholarly journals Benchmarking microbiome transformations favors experimental quantitative approaches to address compositionality and sampling depth biases

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Verónica Lloréns-Rico ◽  
Sara Vieira-Silva ◽  
Pedro J. Gonçalves ◽  
Gwen Falony ◽  
Jeroen Raes
Keyword(s):  
Microbial Communities ◽  
Quantitative Methods ◽  
Microbial Load ◽  
Metagenomic Sequencing ◽  
Sampling Depth ◽  
Microbiome Research ◽  
Microbiome Data ◽  
The Impact ◽  
Analytical Approaches ◽  
Quantitative Approaches

AbstractWhile metagenomic sequencing has become the tool of preference to study host-associated microbial communities, downstream analyses and clinical interpretation of microbiome data remains challenging due to the sparsity and compositionality of sequence matrices. Here, we evaluate both computational and experimental approaches proposed to mitigate the impact of these outstanding issues. Generating fecal metagenomes drawn from simulated microbial communities, we benchmark the performance of thirteen commonly used analytical approaches in terms of diversity estimation, identification of taxon-taxon associations, and assessment of taxon-metadata correlations under the challenge of varying microbial ecosystem loads. We find quantitative approaches including experimental procedures to incorporate microbial load variation in downstream analyses to perform significantly better than computational strategies designed to mitigate data compositionality and sparsity, not only improving the identification of true positive associations, but also reducing false positive detection. When analyzing simulated scenarios of low microbial load dysbiosis as observed in inflammatory pathologies, quantitative methods correcting for sampling depth show higher precision compared to uncorrected scaling. Overall, our findings advocate for a wider adoption of experimental quantitative approaches in microbiome research, yet also suggest preferred transformations for specific cases where determination of microbial load of samples is not feasible.

Random Vibration of Composite Saddle Membrane Structure under the Impact Loading

2021 ◽  
pp. 114020
Author(s):  
Changjiang Liu ◽  
Haibing Xie ◽  
Xiaowei Deng ◽  
Jian Liu ◽  
Mengfei Wang ◽  
...  
Keyword(s):  
Impact Loading ◽  
Membrane Structure ◽  
Random Vibration ◽  
The Impact

Numerical Simulation and Experimental Measurement of a Printed Circuit Board Subjected to Drop Test

2009 ◽  
Vol 419-420 ◽  
pp. 37-40
Author(s):  
Shiuh Chuan Her ◽  
Shien Chin Lan ◽  
Chun Yen Liu ◽  
Bo Ren Yao
Keyword(s):  
Finite Element ◽  
Experimental Measurement ◽  
Test Specimen ◽  
Printed Circuit Board ◽  
Drop Impact ◽  
Simulation Technique ◽  
Drop Test ◽  
Circuit Board ◽  
Printed Circuit ◽  
The Impact

Drop test is one of the common methods for determining the reliability of electronic products under actual transportation conditions. The aim of this study is to develop a reliable drop impact simulation technique. The test specimen of a printed circuit board is clamped at two edges on a test fixture and mounted on the drop test machine platform. The drop table is raised at the height of 50mm and dropped with free fall to impinge four half-spheres of Teflon. One accelerometer is mounted on the center of the specimen to measure the impact pulse. The commercial finite element software ANSYS/LS-DYNA is applied to compute the impact acceleration and dynamic strain on the test specimen during the drop impact. The finite element results are compared to the experimental measurement of acceleration with good correlation between simulation and drop testing. With the accurate simulation technique, one is capable of predicting the impact response and characterizing the failure mode prior to real reliability test.

The Power of Followers That do not Follow: Investigating the Effects of Follower Resistance, Leader Implicit Followership Theories and Leader Negative Affect on the Emergence of Destructive Leader Behavior

2021 ◽  
pp. 154805182110124
Author(s):  
Amelie V. Güntner ◽  
Kai N. Klasmeier ◽  
Florian E. Klonek ◽  
Simone Kauffeld
Keyword(s):  
Negative Affect ◽  
Leader Behavior ◽  
Destructive Leadership ◽  
Causal Inferences ◽  
Within Subjects ◽  
The Impact ◽  
Analytical Approaches ◽  
The Relationship ◽  
Implicit Followership Theories ◽  
Theory X

This study focuses on follower resistance as a potential antecedent of destructive leader behavior and examines leader-related moderators and mediators to help explain the relationship between follower resistance and destructive leader behavior. Drawing from implicit followership theories, we propose that the relationship between follower resistance and destructive leader behavior is moderated by leaders’ Theory X schema. Furthermore, we build on affective events theory to hypothesize that follower resistance increases destructive leader behavior via leaders’ negative affect. We tested our hypotheses in a within-subjects online field experiment. Our study findings demonstrate that follower resistance increases destructive leader behavior and that this relationship is mediated through leaders’ negative affect and moderated by leaders’ Theory X schema. We discuss theoretical implications regarding the impact of (resistant) follower behavior on destructive leadership and offer methodological advances in terms of research design and analytical approaches to deal with endogeneity issues and derive causal inferences. Lastly, we derive practical implications for utilizing follower resistance.

Suppressing Cracking in Resistance Welding AA5754 by Mechanical Means

2000 ◽  
Author(s):  
Hongyan Zhang ◽  
Jacek Senkara ◽  
Xin Wu
Keyword(s):  
Temperature Field ◽  
Crack Initiation ◽  
Spot Welding ◽  
Mechanical Analysis ◽  
Crack Initiation And Propagation ◽  
State Of Stress ◽  
Initiation And Propagation ◽  
Thermal Mechanical Analysis ◽  
The Impact ◽  
Analytical Approaches

Abstract In this paper mechanical aspects of cracking during single- and multi-spot welding of AA5754 was investigated by both experimental and analytical approaches. The impact of mechanical loading on crack initiation and propagation was studied with the consideration of various process parameters including the loading imposed by electrodes, the formation of liquid nugget, and constraining factors during and after welding. Tensile properties of AA5754 and their dependence on the temperature were tested at room and up to solidus temperatures, in order to provide a reference of cracking stress. Thermal-mechanical analysis was conducted based on the temperature field around the nugget and the state of stress encountered during welding. This analysis revealed that tensile stress might build up in the vicinity of the nugget during cooling, thus explained the experimental observation. General guidelines for suppressing cracking were proposed, i.e. to provide sufficient constraint around the weld spot during and after welding.

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