Analysis of Failure in Dual Phase Steel Sheets Subject to Electrohydraulic Forming

2014 ◽  
Vol 136 (5) ◽  
Author(s):  
Javad Samei ◽  
Daniel E. Green ◽  
Sergey Golovashchenko
Keyword(s):  
High Strain Rate ◽  
Strain Rate ◽  
Dual Phase Steel ◽  
High Strain ◽  
Dual Phase ◽  
Dual Phase Steels ◽  
Electrohydraulic Forming ◽  
Steel Sheets ◽  
Conical Die ◽  
The Impact

In previous work, the formability of dual phase steel sheets formed under quasi-static and high strain rate conditions was investigated in macroscale (Golovashchenko et al., 2013, “Formability of Dual Phase Steels in Electrohydraulic Forming,” J. Mater. Process. Technol., 213, pp. 1191–1212) and microscale (Samei et al., 2013, “Quantitative Microstructural Analysis of Formability Enhancement in Dual Phase Steels Subject to Electrohydraulic Forming,” J. Mater. Eng. Perform., 22(7), pp. 2080–2088). The Nakazima test and electrohydraulic forming (EHF) were used for quasi-static and high strain rate forming, respectively. It was shown that dual phase steel sheets exhibit hyperplastic behavior when subject to EHF into a conical die and the micromechanisms of formability improvement were discussed (Samei et al., 2014, “Metallurgical Investigations on Hyperplasticity in Dual Phase Steel Sheets,” ASME J. Manuf. Sci. Eng. (in press)). In this paper, mechanisms of failure in dual phase steels formed under quasi-static and EHF conditions are discussed. For this purpose, the nucleation, growth, and volume fraction of voids were studied. Also, fractography was carried out to understand the different types of fractures in the three grades of dual phase steels. The main objective of this work was to determine how failure was suppressed in the EHF specimens formed in the conical die compared to the Nakazima specimens. The impact of the sheet against the die was found to be the major reason for the delay in failure in the EHF specimens.

Metallurgical Investigations on Hyperplasticity in Dual Phase Steel Sheets

2014 ◽  
Vol 136 (4) ◽  
Author(s):  
Javad Samei ◽  
Daniel E. Green ◽  
Sergey Golovashchenko
Keyword(s):  
Dual Phase Steel ◽  
Microstructural Analysis ◽  
Relative Deformation ◽  
Dual Phase ◽  
Dual Phase Steels ◽  
Electrohydraulic Forming ◽  
Steel Sheets ◽  
Two Phases ◽  
Static Conditions ◽  
High Strain Rate Forming

Several researchers have reported that dual phase steel sheets exhibit hyperplasticity, that is, a significant formability improvement under certain high strain rate forming conditions. Hyperplastic behavior of dual phase steels formed using an electrohydraulic forming (EHF) process was previously investigated by the authors at both macro- (Golovashchenko et al., 2013, “Formability of Dual Phase Steels in Electrohydraulic Forming,” J. Mater. Process. Technol., 213, pp. 1191–1212) and microscales (Samei et al., 2013, “Quantitative Microstructural Analysis of Formability Enhancement in Dual Phase Steels Subject to Electrohydraulic Forming,” J. Mater. Eng. Perform., 22(7), pp. 2080–2088). A relative deformation improvement of approximately 20% in ferrite grains and 100% in martensite islands was reported in the EHF specimens compared to specimens formed under quasi-static conditions. In this paper, the remarkable deformation improvements of the constituents are discussed in terms of metallurgical mechanisms of deformation. The nucleation and multiplication of dislocations in ferrite and deformation twinning in martensite were found to be the principal mechanisms responsible for the significant improvements of deformation in EHF. In addition, these mechanisms enhance the plastic compatibility between the two phases which reduces the risk of decohesion and delays the onset of fracture in EHF specimens.

scholarly journals Anisotropic deformation and damage of dual-phase Ti-6Al-4V under high strain rate loading

2019 ◽  
Vol 742 ◽  
pp. 532-539 ◽  
Author(s):  
J. Tan ◽  
L. Lu ◽  
H.Y. Li ◽  
X.H. Xiao ◽  
Z. Li ◽  
...  
Keyword(s):  
High Strain Rate ◽  
Strain Rate ◽  
High Strain ◽  
Dual Phase ◽  
Strain Rate Loading ◽  
Anisotropic Deformation

scholarly journals High Strain Rate Properties of High Strength Steel Sheets

2011 ◽  
Vol 2 (4) ◽  
pp. 109-113 ◽  
Author(s):  
Akihiro Uenishi ◽  
Hiroshi Yoshida ◽  
Shigeru Yonemura ◽  
Shunji Hiwatashi ◽  
Satoshi Hirose ◽  
...  
Keyword(s):  
High Strain Rate ◽  
Strain Rate ◽  
High Strength Steel ◽  
High Strain ◽  
High Strength ◽  
Steel Sheets

scholarly journals Carbon Nanotube Peapods Under High-Strain Rate Conditions: A Molecular Dynamics Investigation

MRS Advances ◽  
2020 ◽  
Vol 5 (33-34) ◽  
pp. 1723-1730
Author(s):  
J. M. De Sousa ◽  
C. F. Woellner ◽  
L. D. Machado ◽  
P. A. S. Autreto ◽  
D. S. Galvao
Keyword(s):  
Molecular Dynamics ◽  
Carbon Nanotube ◽  
High Strain Rate ◽  
Strain Rate ◽  
High Strain ◽  
Optical Modulation ◽  
Carbon Structures ◽  
Dynamics Simulations ◽  
Forms Of Carbon ◽  
The Impact

ABSTRACTNew forms of carbon-based materials have received great attention, and the developed materials have found many applications in nanotechnology. Interesting novel carbon structures include the carbon peapods, which are comprised of fullerenes encapsulated within carbon nanotubes. Peapod-like nanostructures have been successfully synthesized, and have been used in optical modulation devices, transistors, solar cells, and in other devices. However, the mechanical properties of these structures are not completely elucidated. In this work, we investigated, using fully atomistic molecular dynamics simulations, the deformation of carbon peapods under high-strain rate conditions, which are achieved by shooting the peapods at ultrasonic velocities against a rigid substrate. Our results show that carbon peapods experience large deformation at impact, and undergo multiple fracture pathways, depending primarily on the relative orientation between the peapod and the substrate, and the impact velocity. Observed outcomes include fullerene ejection, carbon nanotube fracture, fullerene, and nanotube coalescence, as well as the formation of amorphous carbon structures.

Performance of 3-D Printed Thermoplastic Polyurethane Under Quasi-Static and High-Strain Rate Loading

2016 ◽  
Author(s):  
S. Chaudhry ◽  
M. Al-Dojayli ◽  
A. Czekanski
Keyword(s):  
High Strain Rate ◽  
Strain Rate ◽  
High Strain ◽  
Split Hopkinson Pressure Bar ◽  
Kolsky Bar ◽  
Pulse Shaper ◽  
Input And Output ◽  
The Impact ◽  
Printing Direction ◽  
Printing Parameters

As 3-D printed materials are being embraced by the manufacturing industries, understanding the response mechanism to high strain rate events becomes a concern to meet requirements for a specific application. In order to improve the mechanical performance of a 3-D printed part, it is necessary to quantify the impact of various printing parameters on the mechanical properties. Initial studies have shown that a difference in 3-D printed material is expected due to the effect of manufacturing parameters such as anisotropy relating to printing direction, infill pattern, infill percentage, layer height and orientation of the part being printed. The main focus of the study is to characterize the effect of the previously mentioned printing parameters under quasi-static and high strain rate (100–1000 /s). In this strain rate regime, the most common apparatus used is the Split Hopkinson pressure bar (also known as Kolsky bar). It consists of a cylindrical metallic bar that has a striker, input and output bar. While the specimen is fixated between the input and output bar, the striker bar is accelerated and triggers the incident bar. As a result, an elastic wave is generated which travels towards the specimen/input bar interface, where some part of it is reflected and the rest is transmitted. The Kolsky bar is adjusted by using a hollow transmitter tube and pulse shaper. Due to an impedance mismatch between the samples and bar material, the amplitude of the transmitted pulse is low. Using a hollow transmitter bar increases this amplitude due to area mismatch between the specimen and tube. Using a pulse shaper between the striker and input bar, the rise time of the elastic compressive wave increases and assists in achieving a constant rate of loading. The compressive stress strain curves were obtained under high strain rates to determine the strain rate effect. To measure the response under static testing conditions, a commercial load frame was used. A comprehensive comparison of dynamic compressive response of samples was performed to characterize the effect of printing parameters.

scholarly journals 2-Step Drop Impact Analysis of a Miniature Mobile Haptic Actuator Considering High Strain Rate and Damping Effects

Micromachines ◽  
2019 ◽  
Vol 10 (4) ◽  
pp. 272 ◽  
Author(s):  
Choi ◽  
Choi ◽  
Kang ◽  
Jeon ◽  
Lee
Keyword(s):  
High Strain Rate ◽  
Strain Rate ◽  
Impact Analysis ◽  
High Strain ◽  
Drop Impact ◽  
Tactile Feedback ◽  
Smart Device ◽  
Damping Effects ◽  
Impact Characteristics ◽  
The Impact

In recent times, the haptic actuators have been providing users with tactile feedback via vibration for a realistic experience. The vibration spring must be designed thin and small to use a haptic actuator in a smart device. Therefore, considerable interests have been exhibited with respect to the impact characteristics of these springs. However, these springs have been difficult to analyze due to their small size. In this study, drop impact experiments and analyses were performed to examine the damages of the mechanical spring in a miniature haptic actuator. Finally, an analytical model with high strain rate and damping effects was constructed to analyze the impact characteristics.

scholarly journals Comparative Study of the Dynamic Deformation of Pure Molybdenum at High Strain Rates and High Temperatures

Materials ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 4847
Author(s):  
Shuai Chen ◽  
Wen-Bin Li ◽  
Xiao-Ming Wang ◽  
Wen-Jin Yao ◽  
Jiu-Peng Song ◽  
...  
Keyword(s):  
High Temperature ◽  
High Strain Rate ◽  
Strain Rate ◽  
Strain Hardening ◽  
High Purity ◽  
High Strain ◽  
Combined Effect ◽  
Strengthening Effect ◽  
Plastic Properties ◽  
The Impact

To study the dynamic plastic properties of high-purity molybdenum materials at high temperature and high strain rate, we designed tests to compare the mechanical behaviour of two high-purity molybdenum materials with different purities and two with different processing deformation conditions under dynamic impact compression in the temperature range of 297–1273 K. We analysed the molybdenum materials’ sensitivities to the strain-hardening effect, strain rate-strengthening effect, and temperature-softening effect as well as the comprehensive response to the combined effect of the strain rate and temperature, the adiabatic impact process, and the microstructure at high temperature and high strain rate. Furthermore, based on a modified Johnson–Cook constitutive model, we quantitatively analysed the flow stresses in these materials. The calculation results strongly agree with the test results. Our findings indicate that the high-purity molybdenum materials show consistent sensitivity to the combined effect of strain rate and temperature regarding the dynamic plastic properties. The materials with higher purity are less sensitive to the combined effect of the strain rate and temperature, and those with less processing deformation experience more pronounced strain-hardening effects. Under high strain rate at room temperature, these materials are highly susceptible to impact embrittlement and decreases in dynamic plastic properties due to intergranular fracture in the internal microstructure. However, increasing the impact environment temperature can significantly improve their plastic properties. The higher the temperature, the better the plastic properties and the higher the impact toughness.

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