Impact friction test method by applying stress wave

1997 ◽  
Vol 37 (4) ◽  
pp. 398-402 ◽  
Author(s):  
K. Ogawa
Keyword(s):  
Stress Wave ◽  
Test Method ◽  
Friction Test ◽  
Friction Test Method

Application of a new, severe-condition friction test method to understand the machining characteristics of Cu–Zn alloys using coated cutting tools

Wear ◽  
2015 ◽  
Vol 344-345 ◽  
pp. 58-68 ◽  
Author(s):  
Christoph Nobel ◽  
Uwe Hofmann ◽  
Fritz Klocke ◽  
Drazen Veselovac ◽  
Hendrik Puls
Keyword(s):  
Cutting Tools ◽  
Test Method ◽  
Friction Test ◽  
Severe Condition ◽  
Machining Characteristics ◽  
Zn Alloys ◽  
Friction Test Method

Friction tests in tube hydroforming

2005 ◽  
Vol 219 (8) ◽  
pp. 587-593 ◽  
Author(s):  
Yeong-Maw Hwang ◽  
Li-Shan Huang
Keyword(s):  
Internal Pressure ◽  
Coefficient Of Friction ◽  
Tube Hydroforming ◽  
Test Method ◽  
Experimental Results ◽  
Friction Test ◽  
Friction Forces ◽  
Axial Feeding ◽  
The Coefficient Of Friction ◽  
Friction Test Method

The objective of this paper is to propose a friction test method to evaluate the performance of different kinds of lubricants and determine their coefficients of friction in tube hydroforming processes. A self-designed apparatus is used to conduct the experiments of friction tests. The coefficient of friction between the tube and the die at the guiding zone is determined. The effects of the internal pressure and the axial feeding velocity on the friction forces and coefficients of friction for various lubricants are discussed. From the experimental results, it is known that MoS2 corresponding to a coefficient of friction of 0.018 is the best lubricant among the evaluated lubricants during tube hydroforming processes.

scholarly journals An Image-Based Impact Test for the High Strain Rate Tensile Properties of Brittle Materials

2018 ◽  
Vol 183 ◽  
pp. 02042
Author(s):  
Lloyd Fletcher ◽  
Fabrice Pierron
Keyword(s):  
Tensile Strength ◽  
Elastic Modulus ◽  
High Strain Rate ◽  
Strain Rate ◽  
Stress Wave ◽  
High Strain ◽  
Brittle Materials ◽  
Test Method ◽  
Strain Rates ◽  
High Strain Rates

Testing ceramics at high strain rates presents many experimental diffsiculties due to the brittle nature of the material being tested. When using a split Hopkinson pressure bar (SHPB) for high strain rate testing, adequate time is required for stress wave effects to dampen out. For brittle materials, with small strains to failure, it is difficult to satisfy this constraint. Because of this limitation, there are minimal data (if any) available on the stiffness and tensile strength of ceramics at high strain rates. Recently, a new image-based inertial impact (IBII) test method has shown promise for analysing the high strain rate behaviour of brittle materials. This test method uses a reflected compressive stress wave to generate tensile stress and failure in an impacted specimen. Throughout the propagation of the stress wave, full-field displacement measurements are taken, from which strain and acceleration fields are derived. The acceleration fields are then used to reconstruct stress information and identify the material properties. The aim of this study is to apply the IBII test methodology to analyse the stiffness and strength of ceramics at high strain rates. The results show that it is possible to identify the elastic modulus and tensile strength of tungsten carbide at strain rates on the order of 1000 s-1. For a tungsten carbide with 13% cobalt binder the elastic modulus was identified as 516 GPa and the strength was 1400 MPa. Future applications concern boron carbide and sapphire, for which limited data exist in high rate tension.

scholarly journals Combined shear/tension testing of fibre composites at high strain rates using an image-based inertial impact test

2018 ◽  
Vol 183 ◽  
pp. 02041 ◽  
Author(s):  
Lloyd Fletcher ◽  
Jared Van-Blitterswyk ◽  
Fabrice Pierron
Keyword(s):  
High Strain Rate ◽  
Strain Rate ◽  
Stress Wave ◽  
Impact Test ◽  
High Strain ◽  
Hopkinson Bar ◽  
Test Method ◽  
Strain Rates ◽  
Fibre Composites ◽  
Split Hopkinson

Testing fibre composites off-axis has been used extensively to explore shear/tension coupling effects. However, off-axis testing at strain rates above 500 s-1 is challenging with a split Hopkinson bar apparatus. This is primarily due to the effects of inertia, which violate the assumption of stress equilibrium necessary to infer stress and strain from point measurements taken on the bars. Therefore, there is a need to develop new high strain rate test methods that do not rely on the assumptions of split Hopkinson bar analysis. Recently, a new image-based inertial impact test has been used to successfully identify the transverse modulus and tensile strength of a unidirectional composite at strain rates on the order of 2000 -1. The image-based inertial impact test method uses a reflected compressive stress wave to generate tensile stress and failure in an impacted specimen. Thus, the purpose of this study is to modify the image-based inertial impact test method to investigate the high strain rate properties of fibre composites using an off-axis configuration. For an off-axis specimen, a combined shear/tension or shear/compression stress state will be obtained. Throughout the propagation of the stress wave, full-field displacement measurements are taken. Strain and acceleration fields are then derived from the displacement fields. The kinematic fields are then processed with the virtual fields method (VFM) to reconstruct stress averages and identify the in-plane stiffness components G12 and E22.

On the Test Method of Dynamic Characteristics of MEMS Components

2013 ◽  
Vol 562-565 ◽  
pp. 119-124 ◽  
Author(s):  
Guang He ◽  
Ya Jun Wang ◽  
Wen Rui Ma
Keyword(s):  
Strain Rate ◽  
Stress Wave ◽  
Dynamic Characteristics ◽  
Optimization Design ◽  
Static Condition ◽  
Test Method ◽  
Testing System ◽  
Split Hopkinson ◽  
Micro Electromechanical System ◽  
Design And Manufacture

The paper developed a set of small split Hopkinson pressure/tensile bar testing system (SSHPB/SSHTB) to study the dynamic characteristics of the micro-electromechanical system (MEMS) material and components, by which the dynamic characteristics of MEMS nickel material and planar S-form micro-spring were got. The dynamic Youngs modulus of LIGA nickel under the strain rate of 2×103s-1 got by the SSHPB is about 250GPa, which is slightly higher than that under static condition. The deformation peculiarity of the planar S-form micro-spring is also got by the SSHTB, which is uneven due to the spreading of the stress wave in the micro-spring. The result of the paper is valuable for providing feasible directions to the optimization design and manufacture of the MEMS components.

scholarly journals Nonuniform Deformation of Cell Structures Owing to Plastic Stress Wave Propagation

2021 ◽  
Vol 2 (4) ◽  
pp. 911-931
Author(s):  
Kohei Tateyama ◽  
Hiroyuki Yamada
Keyword(s):  
Strain Rate ◽  
Stress Wave ◽  
Nickel Foam ◽  
Test Method ◽  
Ni Foam ◽  
Nonuniform Deformation ◽  
Cell Structures ◽  
Silicone Foam ◽  
The Impact ◽  
Plastic Stress

In cell structures, unlike in dense bodies, nonuniform deformation occurs from the impact end, even at velocities in the order of tens to hundreds of meters per second. In this study, we experimentally examine the nonuniform deformation mechanism of cell structures. They prepared two kinds of specimens: nickel foam (Ni foam) and silicone-rubber-filled nickel foam (Ni/silicone foam). As a dynamic and impact test method (compression velocity of 20 m/s or more), we used a dynamic and impact load-measuring apparatus with opposite load cells to evaluate the loads on both ends of the specimen in one test. At compression velocities of 20 m/s or less, no nonuniform deformations were observed in the Ni foam and the Ni/silicone foam, and the loads on the impact and the fixed ends achieved force equilibrium. The Ni foam showed no change with an increasing strain rate, and the Ni/silicone foam showed a strong strain rate dependence of the flow stress. At a compression velocity of approximately 26 m/s, the loads differed at the two ends of the Ni/silicone foam, and we observed nonuniform deformation from the impact end. The results of the visualization of the load and deformation behavior obtained from both ends of the specimen revealed that the velocity of the plastic stress wave and the length of the specimens are important for nonuniform deformation.

Determining Modulus of Elasticity of Ancient Structural Timber

2011 ◽  
Vol 217-218 ◽  
pp. 407-412 ◽  
Author(s):  
Hou Jiang Zhang ◽  
Lei Zhu ◽  
Yan Liang Sun ◽  
Xi Ping Wang ◽  
Hai Cheng Yan
Keyword(s):  
Stress Wave ◽  
Modulus Of Elasticity ◽  
Correlation Coefficients ◽  
Test Method ◽  
Bending Test ◽  
Structural Failure ◽  
Wood Component ◽  
Linear Relationships ◽  
Standard Specimens ◽  
Beijing China

During maintenance of ancient timber architectures, it is important to determine mechanical properties of the wood component materials non-destructively and effectively, so that degraded members may be replaced or repaired to avoid structural failure. Experimental materials are four larch (Larix principis-rupprechtii Mayr.) components, which were taken down from the drum-tower of Zhengjue Temple of Yuanmingyuan (Old Summer Palace), Beijing, China. The larch components were cut into standard specimens first, and then stress wave transmission times, resistograph and densities were tested. Product of resitograph and stress wave speed squared is defined as modulus of stress-resistograph. Comparing with the modulus of elasticity (MOE) of the specimens tested by the traditional bending test method, it is found that there is a linear relationships between the modulus of stress-resistograph and modulus of elasticity (MOE), and the correlation coefficients are 0.7111. In order to better evaluate the modulus of elasticity (MOE) with the modulus of stress-resistograph, 95% confidence regression lines are suggested to be used for the future calculation.

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