scholarly journals Reactions of Al-PTFE under Impact and Quasi-Static Compression

2015 ◽  
Vol 2015 ◽  
pp. 1-6 ◽  
Author(s):  
Bin Feng ◽  
Xiang Fang ◽  
Yu-chun Li ◽  
Shuang-zhang Wu ◽  
Yi-ming Mao ◽  
...  
Keyword(s):  
Energy Level ◽  
Dynamic Test ◽  
Dynamic Impact ◽  
Sem Images ◽  
Static Loads ◽  
Static Compression ◽  
Static Tests ◽  
The Difference ◽  
Quasi Static Compression

Conventionally, the Al-PTFE is thought to be inert under quasi-static or static loads. However, here we reported an initiation phenomenon of Al-PTFE under quasi-static compression. Quasi-static tests suggest that reacted Al-PTFE samples had much higher toughness than unreacted samples. Dynamic test showed that the energy level needed to initiate the material was similar for quasi-static compression (88–100 J) and dynamic impact (77–91 J). The difference in density indicates that unreacted Al-PTFE has a higher crystallinity, which leads to the lower toughness. SEM images show numerous PTFE fibrils in unreacted composites which made the sample harder to crack and initiate.

Static and Dynamic Properties of Various Baseballs

1998 ◽  
Vol 14 (4) ◽  
pp. 390-400 ◽  
Author(s):  
Shonn P. Hendee ◽  
Richard M. Greenwald ◽  
Joseph J. Crisco
Keyword(s):  
Energy Loss ◽  
Dynamic Properties ◽  
Impact Behavior ◽  
Dynamic Impact ◽  
Ball Impact ◽  
Static Compression ◽  
Stationary Target ◽  
Static Tests ◽  
Static Mechanical ◽  
Force Time

In this study we investigated the compressive quasi-static mechanical properties and dynamic impact behavior of baseballs. Our purpose was to determine if static testing could be used to describe dynamic ball impact properties, and to compare static and dynamic properties between traditional and modified baseballs. Average stiffness and energy loss from 19 ball models were calculated from quasi-static compression data. Dynamic impact variables were determined from force–time profiles of balls impacted into a flat stationary target at velocities from 13.4 to 40.2 m/s. Peak force increased linearly with increasing ball model stiffness. Impulse of impact increased linearly with ball mass. Coefficient of restitution (COR) decreased with increasing velocity in all balls tested, although the rate of decrease varied among the different ball models. Neither quasi-static energy loss nor hysteresis was useful in predicting dynamic energy loss (COR2). The results between traditional and modified balls varied widely in both static and dynamic tests, which is related to the large differences in mass and stiffness between the two groups. These results indicate that static parameters can be useful in predicting some dynamic impact variables, potentially reducing the complexity of testing. However, some variables, such as ball COR, could not be predicted with the static tests performed in this study.

Quasi-Static Lateral Crushing of Non-Woven Kenaf Fibre Reinforced Composite Hexagonal Tubes

2015 ◽  
Vol 1119 ◽  
pp. 652-656
Author(s):  
M.F.M. Alkbir ◽  
S.M. Sapuan ◽  
A.A. Nuraini ◽  
M.R. Ishak
Keyword(s):  
Failure Modes ◽  
Load Carrying Capacity ◽  
Static Compression ◽  
Static Tests ◽  
Reinforced Composite ◽  
Kenaf Fibre ◽  
Hexagonal Shape ◽  
Load Carrying ◽  
Longitudinal Cracks ◽  
Quasi Static Compression

This investigation presents the lateral quasi-static compression crushing testing and load carrying capacity of three different hexagonal angles ranging from 40ο to 60ο. The objective of this study is to understand the effect of hexagonal shape on the progressive deformation, crashworthiness and failure modes. A hand lay-up technique was used to fabricate a hexagonal composite. Quasi-static tests have been carried out on all the specimens tested. From the experimental study, it was found that the tubes crushed with four longitudinal cracks on all sides of the tubes. Furthermore, the energy absorption capability, decreased with the increase of the hexagonal side angles from 40ο to 60ο.

Surface energy of coal particles under quasi-static compression and dynamic impact based on fractal theory

Fuel ◽  
2020 ◽  
Vol 264 ◽  
pp. 116835 ◽  
Author(s):  
Chenghao Wang ◽  
Yuanping Cheng ◽  
Minghao Yi ◽  
Biao Hu ◽  
Zhaonan Jiang
Keyword(s):  
Surface Energy ◽  
Fractal Theory ◽  
Dynamic Impact ◽  
Static Compression ◽  
Coal Particles ◽  
Quasi Static Compression

scholarly journals Dynamic Response of Electro-Mechanical Properties of Cement-Based Piezoelectric Composites

2021 ◽  
Vol 11 (24) ◽  
pp. 11925
Author(s):  
Yi Li ◽  
Youwei Zhang ◽  
Haiwei Dong ◽  
Wenjie Cheng ◽  
Chaoming Shi ◽  
...  
Keyword(s):  
Strain Rate ◽  
Impact Loading ◽  
Mechanical Response ◽  
Dynamic State ◽  
Dynamic Impact ◽  
Piezoelectric Composites ◽  
Static Compression ◽  
Static State ◽  
Dynamic Impact Loading ◽  
Quasi Static Compression

By employing ordinary Portland cement as a matrix and PZT-5H piezoelectric ceramic as the functional body, 1-3 and 2-2 cement-based piezoelectric composites were prepared. Quasi-static compression tests were performed along with dynamic impact loading tests to study the electro-mechanical response characteristics of 1-3 and 2-2 cement-based piezoelectric composites. The research results show that both composites exhibit strain rate effects under quasi-static compression and dynamic impact loading since they are strain-rate sensitive materials. The sensitivity of the two composites has a non-linear mutation point: in the quasi-static state, the sensitivity of 1-3 and 2-2 composites is 157 and 169 pC/N, respectively; in the dynamic state, the respective sensitivity is 323 and 296 pC/N. Although the sensitivity difference is not significant, the linear range of the 2-2 composite is 24.8% and 61.3% larger than that of the 1-3 composite under quasi-static compression and dynamic impact loading, respectively. Accordingly, the 2-2 composite exhibits certain advantages as a sensor material, irrespective of whether it is subjected to quasi-static or dynamic loading.

Experimental Characterization for Helmet Pads

2017 ◽  
Author(s):  
Timothy G. Zhang ◽  
Chris Meredith ◽  
Allison Muller ◽  
Paul Moy ◽  
Sikhanda S. Satapathy
Keyword(s):  
Compression Tests ◽  
Dynamic Impact ◽  
Engineering Strain ◽  
Static Compression ◽  
Static Tests ◽  
Material Stiffness ◽  
Rigid Projectile ◽  
Time Histories ◽  
The Impact ◽  
Impact Experiments

In this study, quasi-static compression and dynamic impact experiments were conducted on helmet pads. Various layers of the foam pad: comfort, stiff and bilayer were tested to characterize their material response. In the compression tests, a piston compressed foam samples at constant velocity. The samples were tested under confined and unconfined conditions. In the dynamic impact experiments, the foam samples were impacted by a rigid projectile. Both the time histories of the force applied to the foam samples and the sample displacement were recorded to calculate the engineering strain and stress in the foam samples. The material stiffness in the impact tests was found to be several times that of the quasi-static tests.

Fracture behavior of Zr55Cu30Al10Ni5 bulk metallic glass under quasi-static and dynamic compression

2008 ◽  
Vol 23 (6) ◽  
pp. 1744-1750 ◽  
Author(s):  
R.Q. Yang ◽  
J.T. Fan ◽  
S.X. Li ◽  
Z.F. Zhang
Keyword(s):  
Metallic Glass ◽  
Strain Rate ◽  
Bulk Metallic Glass ◽  
Dynamic Fracture ◽  
Fracture Behavior ◽  
Maximum Shear Stress ◽  
Instability Criterion ◽  
Static Compression ◽  
Static Tests ◽  
Quasi Static Compression

Fracture behavior of Zr55Cu30Al10Ni5 bulk metallic glass was investigated under quasi-static compression at strain rate of 10−4/s using an Instron testing machine and dynamic split Hopkinson bar (SHPB) compression with strain rate of about 1900–4300/s. Pronounced strain softening, especially past the peak stress, was observed under SHPB tests and compared with the distinct flow serrations under quasi-static tests. Scanning electron microscope revealed that the angle between the loading axis and major shear plane is less than 45°, deviating from the maximum shear stress plane. Microscopically, unlike the ordinary veinlike pattern found in quasi-static compression, the elongated veinlike pattern was observed at the onset position of rapid shearing under dynamic test. A closely arrayed dendritelike structure dominated the dynamic fracture, consequently, and should be the major pattern representing the rapid shear band propagation. In addition, a transition state from veinlike to dendritelike pattern was observed at the final instantaneous fracture region in quasi-static tests. Evidence revealed the characteristic dimension of dynamic fracture surface complies with Taylor’s meniscus instability criterion. The roles of free volume and adiabatic heating on the fracture strength and stress concentration on the fracture morphology are also discussed.

scholarly journals Scanning Accuracy of Bracket Features and Slot Base Angle in Different Bracket Materials by Four Intraoral Scanners: An In Vitro Study

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 365
Author(s):  
Seon-Hee Shin ◽  
Hyung-Seog Yu ◽  
Jung-Yul Cha ◽  
Jae-Sung Kwon ◽  
Chung-Ju Hwang
Keyword(s):  
Stainless Steel ◽  
In Vitro Study ◽  
Sem Images ◽  
Polycrystalline Alumina ◽  
Base Angle ◽  
Accurate Expression ◽  
Dental Model ◽  
Alumina Composite ◽  
The Difference

The accurate expression of bracket prescription is important for successful orthodontic treatment. The aim of this study was to evaluate the accuracy of digital scan images of brackets produced by four intraoral scanners (IOSs) when scanning the surface of the dental model attached with different bracket materials. Brackets made from stainless steel, polycrystalline alumina, composite, and composite/stainless steel slot were considered, which have been scanned from four different IOSs (Primescan, Trios, CS3600, and i500). SEM images were used as references. Each bracket axis was set in the reference scan image, and the axis was set identically by superimposing with the IOS image, and then only the brackets were divided and analyzed. One-way analysis of variance (ANOVA) was used to compare the differences. The difference between the manufacturer’s nominal torque and bracket slot base angle was 0.39 in SEM, 1.96 in Primescan, 2.04 in Trios, and 5.21 in CS3600 (p < 0.001). The parallelism, which is the difference between the upper and lower angles of the slot wall, was 0.48 in SEM, 7.00 in Primescan, 5.52 in Trios, 6.34 in CS3600, and 23.74 in i500 (p < 0.001). This study evaluated the accuracy of the bracket only, and it must be admitted that there is some error in recognizing slots through scanning in general.

scholarly journals Analysis of the Strain and Stress Fields of Cardboard Box during Compression by 3D Digital Image Correlation

2010 ◽  
Vol 24-25 ◽  
pp. 103-108 ◽  
Author(s):  
Jeremie Viguié ◽  
P.J.J. Dumont ◽  
P. Vacher ◽  
Laurent Orgéas ◽  
I. Desloges ◽  
...  
Keyword(s):  
Compression Strength ◽  
Compressive Loading ◽  
Image Correlation ◽  
Parallel Plates ◽  
Static Compression ◽  
3D Digital Image Correlation ◽  
Plastic Materials ◽  
Semi Empirical ◽  
And Storage ◽  
Quasi Static Compression

Corrugated boards with small flutes appear as good alternatives to replace packaging folding boards or plastic materials due their small thickness, possibility of easy recycling and biodegradability. Boxes made up of these materials have to withstand significant compressive loading conditions during transport and storage. In order to evaluate their structural performance, the box compression test is the most currently performed experiment. It consists in compressing an empty container between two parallel plates at constant velocity. Usually it is observed that buckling phenomena are localized in the box panels, which bulge out during compression [1]. At the maximum recorded compression force, the deformation localises around the box corners where creases nucleate and propagate. This maximum force is defined as the quasi-static compression strength of the box. The prediction of such strength is the main topic of interest of past and current research works. For example, the box compression behaviour of boxes was studied by Mc Kee et al. [2] and Urbanik [3], who defined semi-empirical formula to predict the box compression strength, as well as by Beldie et al. [4] and Biancolini et al. [5] by finite element simulations. But comparisons of these models with experimental results remain rather scarce and limited.

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