scholarly journals On the Development of a Release Mechanism for a Split Hopkinson Tension and Compression Bar

Materials ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 7609
Author(s):  
Georg Baumann ◽  
Dominik Niederkofler ◽  
Christian Ellersdorfer ◽  
Florian Feist
Keyword(s):  
Numerical Study ◽  
Compressive Loading ◽  
High Strength ◽  
Experimental Tests ◽  
Release Mechanism ◽  
Mechanical Characterisation ◽  
Ultra High Strength Steel ◽  
Tension And Compression ◽  
Split Hopkinson ◽  
Rising Time

Split Hopkinson bars are used for the dynamic mechanical characterisation of materials under high strain rates. Many of these test benches are designed in such a way that they can either be used for compressive or tensile loading. The goal of the present work is to develop a release mechanism for an elastically pre-stressed Split Hopkinson bar that can be universally used for tensile or compressive loading. The paper describes the design and dimensioning of the release mechanism, including the brittle failing wear parts from ultra-high strength steel. Additionally, a numerical study on the effect of the time-to-full-release on the pulse-shape and pulse-rising time was conducted. The results of the analytical dimensioning approaches for the release mechanism, including the wear parts, were validated against experimental tests. It can be demonstrated that the designed release concept leads to sufficiently short and reproducible pulse rising times of roughly 0.11 ms to 0.21 ms, depending on the pre-loading level for both the tension and compression wave. According to literature, the usual pulse rising times can range from 0.01 ms to 0.35 ms, which leads to the conclusion that a good average pulse rising time was achieved with the present release system.

scholarly journals On the Development of Material Constitutive Model for 45CrNiMoVA Ultra-High-Strength Steel

Metals ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 374 ◽  
Author(s):  
Xin Hu ◽  
Lijing Xie ◽  
Feinong Gao ◽  
Junfeng Xiang
Keyword(s):  
Constitutive Model ◽  
Strain Rate ◽  
High Strength Steel ◽  
Split Hopkinson Pressure Bar ◽  
High Strength ◽  
Model Parameters ◽  
Hopkinson Pressure Bar ◽  
Simulation Accuracy ◽  
Ultra High Strength Steel ◽  
Split Hopkinson

For the implementation of simulations for large plastic deformation processes such as cutting and impact, the development of the constitutive models for describing accurately the dynamic plasticity and damage behaviors of materials plays a crucial role in the improvement of simulation accuracy. This paper focuses on the dynamic behaviors of 45CrNiMoVA ultra-high-strength torsion bar steel. According to investigation of the Split-Hopkinson pressure bar (SHPB) and Split-Hopkinson tensile bar (SHTB) tests at different strain rate and different temperatures, 45CrNiMoVA ultra-high-strength steel is characterized by strain hardening, strain-rate hardening and thermal softening effects. Based on the analysis on the mechanism of the experimental results and the limitation of classic Johnson-Cook (J-C) constitutive model, a modified J-C model by considering the phase transition at high temperature is established. The multi-objective optimization fitting method was used for fitting model parameters. Compared with the classic J-C constitutive model, the fitting accuracy of the modified J-C model significantly improved. In addition, finite element simulations for SHPB and SHTB based on the modified J-C model are conducted. The SHPB stress-strain curves and the fracture morphology of SHTB samples from simulations are in good agreement with those from tests.

Numerical Study of Round-Robin Tests on the Split Hopkinson Pressure Bar Technique

2013 ◽  
Vol 535-536 ◽  
pp. 518-521 ◽  
Author(s):  
Muhammad A. Kariem ◽  
Dong Ruan ◽  
John H. Beynon
Keyword(s):  
Split Hopkinson Pressure Bar ◽  
Numerical Study ◽  
High Strength ◽  
Round Robin ◽  
Hopkinson Pressure Bar ◽  
Element Analysis ◽  
Acceptable Error ◽  
Aisi 4140 ◽  
Split Hopkinson ◽  
Pressure Bar

It is known that the split Hopkinson pressure bar (SHPB) technique has not been standardised yet. The standardised SHPB technique is necessary in order to provide guidelines for determining the intrinsic material properties. This paper examines whether consistent results can be achieved from various sets of SHPBs. Finite element analysis has been conducted using ANSYS/LS-DYNA. Numerical simulation of the round-robin tests was conducted to study the consistency of results for OFHC copper, which were obtained from three sets of apparatus, namely: 12.7 mm diameter SHPB made from the AISI 4140 steel, 13 mm diameter SHPB made from the high strength steel (HSS) and 14.5 mm diameter SHPB made from maraging steel 350 (AISI 18Ni). The current study shows that consistent flow stresses (within an acceptable error of 2.5%) were obtained from those three sets of SHPBs, which indicates the possibility of SHPB standardisation in the future.

scholarly journals Numerical study for determination of pulse shaping design variables in SHPB apparatus

2013 ◽  
Vol 61 (2) ◽  
pp. 459-466 ◽  
Author(s):  
P. Baranowski ◽  
J. Malachowski ◽  
R. Gieleta ◽  
K. Damaziak ◽  
L. Mazurkiewicz ◽  
...  
Keyword(s):  
Pulse Shaping ◽  
Split Hopkinson Pressure Bar ◽  
Numerical Study ◽  
Experimental Tests ◽  
Peak Shape ◽  
Hopkinson Pressure Bar ◽  
Design Variables ◽  
Split Hopkinson ◽  
Pulse Peak ◽  
Pressure Bar

Abstract High strain rate experimental tests are essential in a development process of materials under strongly dynamic conditions. For such a dynamic loading the Split Hopkinson Pressure Bar (SHPB) has been widely used to investigate dynamic behaviour of various materials. It was found that for different materials various shapes of a generated wave are desired. This paper presents a parametric study of Split Hopkinson Pressure Bar in order to find striker’s design variables, which influence the pulse peak shape in the incident bar. With experimental data given it was possible to verify the developed numerical model, which was used for presented investigations. Dynamic numerical simulations were performed using explicit LS-Dyna code with a quasi-optimization process carried out using LS-Opt software in order to find striker’s design variables, which influence the pulse peak shape.

scholarly journals Experimental and Numerical Study of Octagonal Composite Column Subject to Various Loading

2017 ◽  
Author(s):  
Mehdi Ebadi Jamkhaneh ◽  
Mohammad Ali Kafi
Keyword(s):  
Numerical Study ◽  
Slenderness Ratio ◽  
Compressive Loading ◽  
Axial Loading ◽  
Experimental Tests ◽  
Composite Column ◽  
Concrete Confinement ◽  
Steel Column ◽  
Different Types ◽  
The Relationship

In this study, experimental tests of the behaviour of steel and partially encased composite (PEC) columns subjected to compressive loading is performed. Evaluation of this type of composite column under axial loading and numerical analysis of its behaviour under combined torsional and axial loading are the main objectives of this study. At first, a parametric study of PEC columns under axial loading was performed in order to find the relationship between flange slenderness ratio of steel column section and concrete confinement. Width-to-thickness ratio of the flange, diameter and spacing of the transverse links were considered as variables in this study. It was observed that dimension of transverse links had almost no effect on the capacity of the specimens, however smaller transverse links spacing increased both capacity and deformability of the specimens. The comparison of the code equations given in CSA S16-14 and EN 1994-1-1 revealed that the equation in CSA S16-14 underestimates the capacity. Furthermore, different types of retrofit of cross-shaped steel column including concrete encasement, use of stiffener plates and transverse links were investigated in this research. Results revealed that concrete confinement and use of transverse links had respectively the most and the least effect on increasing torsional capacity of the specimens.

scholarly journals Experimental and Numerical Study on the Behavior of Dyneema� HB26 Composite in Compression

2019 ◽  
Vol 57 (2) ◽  
pp. 113-122
Author(s):  
Florina Bucur ◽  
Adrian Rotariu ◽  
Liviu Matache ◽  
Florin Baciu ◽  
Gabriel Jiga ◽  
...  
Keyword(s):  
Split Hopkinson Pressure Bar ◽  
Numerical Study ◽  
Low Cost ◽  
Testing Machine ◽  
Compressive Load ◽  
High Strength ◽  
Experimental Tests ◽  
Hopkinson Pressure Bar ◽  
Course Of Action ◽  
Pressure Bar

In the last decades as the need for high economical and technical efficiency items/applications became acute, lightweight, high strength and low-cost materials development and investigation emerged as a logical and promising course of action. With high potential for both military and civil sector, the ultra-high molecular weight polyethylene (UHMWPE) is considered a new class of material. Among this class, the Dyneema� HB26 composite is of most interest for the present study. The present paper focuses on the static and dynamic investigation of the HB26 mechanical behavior experiencing an out of plane compressive load. For experimental purposes, using a 15 mm thickness panel two types of samples (cylindrical and cubic samples) were processed. For compression test Instron Testing Machine and the Split Hopkinson Pressure Bar (SHPB) were used. The experimental tests were then compared against the numerical findings highlighting a good consistency.

Bendability of Ultra-High-Strength Steel

2009 ◽  
Vol 410-411 ◽  
pp. 611-620 ◽  
Author(s):  
Anu Väisänen ◽  
Kari Mäntyjärvi ◽  
Jussi A. Karjalainen
Keyword(s):  
High Strength ◽  
Experimental Tests ◽  
Fe Analysis ◽  
Large Radius ◽  
Test Results ◽  
Complex Phase ◽  
Air Bending ◽  
Ultra High Strength Steel ◽  
Bending Process ◽  
Punch Radius

Utilisation of ultra-high-strength (UHS) steels is rapidly spreading from the automotive industry into many other application areas. It is necessary to know how these materials behave in common production processes such as air bending. The bendability of UHS steels is much lower compared to normal and high-strength construction steels. In this work, experimental tests were carried out using complex phase (CP) bainitic-martensitic UHS steels (YS/TS 960/1000 and 1100/1250) and S650MC HS steel in order to inspect material bendability and possible problems in the bending process. Mechanical and geometrical damages were registered and classified. The bending method used was air bending and press brake bending with an elastic lower die. The FE analysis was used to understand the stress state at different points in the material and build-up of failure. As UHS steels cannot stand large local strains, a large radius must be used in air bending. The results show that even when a large radius is used in air bending, the strain is not evenly distributed; there is a clear high strain area in the middle of the bend. It was also possible to simulate the other phenomena occurring in experimental tests, such as losing contact with the punch and ‘nut-like’ geometry, using FE analysis. Experimental test results also show that by using an elastic lower die, it is possible to avoid unwanted phenomena and obtain an almost 50% smaller punch radius, but the required force is 50% bigger than that required in air bending.

Numerical Study of Asymmetric Friction Connections (AFC) with Large Grip Length Bolts

2018 ◽  
Vol 763 ◽  
pp. 600-608
Author(s):  
Mandi Hatami ◽  
Gregory A. MacRae ◽  
Geoffrey W. Rodgers ◽  
George Charles Clifton
Keyword(s):  
Numerical Study ◽  
Experimental Studies ◽  
Equivalent Plastic Strain ◽  
High Strength ◽  
Experimental Tests ◽  
Fe Model ◽  
Other Information ◽  
Bearing Stress ◽  
Lateral Displacements ◽  
Bolt Diameter

A Finite Element (FE) model is used to simulate the experimental behaviour of high strength bolts in asymmetric friction connections (AFC). Two M16 connections tested previously are modelled using ABAQUS and are subjected to cyclic lateral displacements. The numerical results were similar to that from previous experimental studies. It was also shown that hysteresis loop strength and stability reduced for longer bolt grip lengths. Other information, which cannot be easily monitored in experimental tests, such as the bearing stress distribution between plates, component equivalent plastic strain, and bolt tension force, were obtained at different sliding distances. It was shown that bolt and plate plastic deformation tended to occur in bolts with a long grip length to bolt diameter ratio.

Performance assessment on high strength steel endplate connections in fire

2016 ◽  
Vol 7 (2) ◽  
pp. 168-178 ◽  
Author(s):  
Xuhong Qiang ◽  
Xu Jiang ◽  
Frans Bijlaard ◽  
Henk Kolstein
Keyword(s):  
Mild Steel ◽  
Ambient Temperature ◽  
High Strength Steel ◽  
Numerical Study ◽  
High Strength ◽  
Experimental Tests ◽  
Content Type ◽  
Rotation Capacity ◽  
Endplate Connections ◽  
In Fire

Purpose This paper aims to investigate and assess a perspective of combining high-strength-steel endplate with mild-steel beam and column in endplate connections. Design/methodology/approach First, experimental tests on high strength steel endplate connections were conducted at fire temperature 550°C and at an ambient temperature for reference. Findings The moment-rotation characteristic, rotation capacity and failure mode of high-strength-steel endplate connections in fire and at an ambient temperature were obtained through tests and compared with those of mild-steel endplate connections. Further, the provisions of Eurocode 3 were validated with test results. Moreover, the numerical study was carried out via ABAQUS and verified against the experimental results. Originality/value It is found that a thinner high-strength-steel endplate can enhance the connection’s rotation capacity both at an ambient temperature and in fire (which guarantees the safety of an entire structure) and simultaneously achieve almost the same moment resistance with a mild steel endplate connection.

Sign in / Sign up

Export Citation Format

Share Document