Characterisation of Aluminium Matrix Syntactic Foams Dynamic Loading

2014 ◽  
Vol 564 ◽  
pp. 449-454 ◽  
Author(s):  
Mohamed Altenaiji ◽  
Zhong Wei Guan ◽  
W. Cantwell ◽  
Y.Y. Zhao
Keyword(s):  
Energy Absorption ◽  
Dynamic Loading ◽  
Mechanical Performance ◽  
High Strain ◽  
Split Hopkinson Pressure Bar ◽  
Aluminium Matrix ◽  
Syntactic Foams ◽  
Loading Conditions ◽  
Static Compression ◽  
Drop Weight

It is a challenging task to develop a lightweight but also strong material with energy absorption capability to be used in vehicles to withstand impact and blast. This paper reports the research results on Aluminium syntactic foams as possible core materials for protection of military vehicles. In order to optimize their mechanical performance the characterisation of the foam behaviour at high strain rates and identification of the underlying mechanisms have been conducted. Mechanical tests were carried out on syntactic foams under high strain rate compression loading. The drop weight and split Hopkinson pressure bar (SHPB) techniques have been used to obtain data on the material behaviour under dynamic loading conditions. It was found that some samples show 30% higher plateau stress in the drop weight test than that of the quasi-static compression. In addition, it was found that the energy absorption of the aluminium matrix syntactic foam is higher than that of the ordinary aluminium foam. Experimental results from the above investigation are compared with the finite element predictions under the same loading conditions. Reasonably good correlation is obtained. The discussion on developing numerical modelling and the related validation are also given.

High Strain Rate Response of Rocks Under Dynamic Loading Using Split Hopkinson Pressure Bar

2017 ◽  
Vol 36 (1) ◽  
pp. 531-549 ◽  
Author(s):  
Sunita Mishra ◽  
Hemant Meena ◽  
Vedant Parashar ◽  
Anuradha Khetwal ◽  
Tanusree Chakraborty ◽  
...  
Keyword(s):  
High Strain Rate ◽  
Strain Rate ◽  
Dynamic Loading ◽  
High Strain ◽  
Split Hopkinson Pressure Bar ◽  
Hopkinson Pressure Bar ◽  
Split Hopkinson ◽  
Pressure Bar

Microstructural and Dynamic Mechanical Characterization of Biodegradable Magnesium-Calcium Alloy for Orthopedic Implants

2014 ◽  
Author(s):  
V. S. Brooks ◽  
Y. B. Guo
Keyword(s):  
Mechanical Properties ◽  
Mechanical Behavior ◽  
High Strain ◽  
Split Hopkinson Pressure Bar ◽  
Dynamic Compression ◽  
Orthopedic Implants ◽  
Strain Rates ◽  
High Strain Rates ◽  
Static Compression ◽  
Metallic Biomaterial

Magnesium-Calcium (Mg-Ca) alloy is an emerging metallic biomaterial for manufacturing biodegradable orthopedic implants. However, very few studies have been conducted on mechanical properties of the bi-phase Mg-Ca alloy, especially at the high strain rates often encountered in manufacturing processes. The mechanical properties are critical to design and manufacturing of Mg-Ca implants. The objective of this study is to study the microstructural and mechanical properties of Mg-Ca0.8 (wt %) alloy. Both elastic and plastic behaviors of the Mg-Ca0.8 alloy were characterized at different strains and strain rates in quasi-static tension and compression testing as well as dynamic split-Hopkinson pressure bar (SHPB) testing. It has been shown that Young’s modulus of Mg-Ca0.8 alloy in quasi-static compression is much higher than those at high strain rates. Yield strength and ultimate strength of the material are very sensitive to strain rates and increase with strain rate in compression. Strain softening also occurs at large strains in dynamic compression. Furthermore, quasi-static mechanical behavior of the material in tension is very different from that in compression. The stress-strain data was repeatable with reasonable accuracy in both deformation modes. In addition, a set of material constants for the internal state variable plasticity model has been obtained to model the dynamical mechanical behavior of the novel metallic biomaterial.

Analysis of the crashworthiness design and collision dynamics of a subway train

2019 ◽  
Vol 234 (10) ◽  
pp. 1117-1128
Author(s):  
Suchao Xie ◽  
Xuanjin Du ◽  
Hui Zhou ◽  
Da Wang ◽  
Zhejun Feng
Keyword(s):  
Finite Element ◽  
Energy Absorption ◽  
Mechanical Performance ◽  
Simulation Analysis ◽  
Element Model ◽  
Collision Dynamics ◽  
Element Analysis ◽  
Static Compression ◽  
Subway Train ◽  
Energy Absorbing

In this study, the crashworthiness of a subway train was assessed by establishing a finite element model for the first three carriages of the train and the track using the Hypermesh software. By utilising the *MAT_HONEYCOMB material model, a honeycomb in an anti-climbing energy-absorbing device was simulated. Moreover, the process of a subway train – travelling at a speed of 25 km/h – colliding with another identical train in a stationary and non-braking state was simulated by employing the finite element analysis software Hypermesh and LS-DYNA. The process of simulation analysis was divided into two parts: (1) analysis of the anti-climbing energy-absorbing devices under static compression for the investigation of energy absorption and (2) collision analysis of the whole train. The contributions of the proposed energy-absorbing structure – at the end of driver’s cab, the coupler and draft gears on each section – to the overall energy absorption in a train collision were calculated. Furthermore, based on the EN15227 standard, the crashworthiness of the train with respect to the survival space for occupants, train acceleration and uplift of wheels relative to the track was evaluated. The coupler of the first carriage fails in a collision at 25 km/h, and the coupler and draft gear are the main energy-absorbing devices. *MAT_HONEYCOMB was used to define the honeycomb materials in anti-climbing energy-absorbing devices and could simulate the mechanical performance thereof. The crashworthiness of the train meets the relevant standard requirements.

Evaluation of Friction at High Strain Rate using the Split Hopkinson Bar

2015 ◽  
Vol 651-653 ◽  
pp. 108-113 ◽  
Author(s):  
Archimede Forcellese ◽  
Edoardo Mancini ◽  
Marco Sasso ◽  
Michela Simoncini
Keyword(s):  
High Strain Rate ◽  
Strain Rate ◽  
Dynamic Loading ◽  
High Strain ◽  
Outer Diameter ◽  
Loading Conditions ◽  
Split Hopkinson ◽  
Dynamic Loading Conditions ◽  
Static And Dynamic Loading ◽  
Frictional Behaviour

The present work aims at studying the influence of strain rate on the frictional behaviour of AA7075 aluminium alloy in the O-annealed temper state. To this purpose, ring compression tests were performed both under quasi-static and dynamic loading conditions. The high strain rate tests were carried out by means of the Split Hopkinson Tension-Compression Bar in the direct version. In both cases, hollow cylindrical samples, characterised by an initial outer diameter to inner diameter to height ratio of 6:3:2, were tested under dry condition and by lubricating with molybdenum disulphide grease. The different frictional behaviour exhibited by AA7075-O under quasi-static and dynamic loading conditions can be attributed to the strain rate effect both on the plastic flow behaviour of the deformed material, and on the thickness of the lubricant film.

scholarly journals Strength and Failure Characteristics of Natural and Water-Saturated Coal Specimens under Static and Dynamic Loads

2018 ◽  
Vol 2018 ◽  
pp. 1-15 ◽  
Author(s):  
Wen Wang ◽  
Heng Wang ◽  
Dongyin Li ◽  
Huamin Li ◽  
Zhumeng Liu
Keyword(s):  
Dynamic Loading ◽  
Split Hopkinson Pressure Bar ◽  
Three Dimensional ◽  
Dynamic Strength ◽  
Hopkinson Pressure Bar ◽  
Static Compression ◽  
One Dimensional ◽  
Before And After ◽  
Loading Tests ◽  
Water Saturated

Rock bursts occur frequently in coal mines, and the mechanical properties of saturated coal specimens under coupled static-dynamic loading need to be studied in detail. Comparative tests of coal specimens having different water content under static and static-dynamic loading are conducted using the split Hopkinson pressure bar (SHPB) and RMT-150C test systems. The results demonstrate that the natural specimen strength is greater than that of seven-day (7D) saturated specimens under both uniaxial compression and triaxial static compression loading; however, the dynamic strength of 7D saturated specimens is lower than that of natural specimens under one-dimensional static-dynamic loading. The particle size of the 7D saturated specimens is relatively small under uniaxial static compression and one-dimensional static-dynamic loading, and the specimen particle sizes before and after static triaxial loading tests and three-dimensional static-dynamic loading tests do not exhibit an obvious difference.

Characterisation of aluminium matrix syntactic foams under drop weight impact

2014 ◽  
Vol 59 ◽  
pp. 296-302 ◽  
Author(s):  
M. Altenaiji ◽  
Z.W. Guan ◽  
W.J. Cantwell ◽  
Y. Zhao ◽  
G.K. Schleyer
Keyword(s):  
Aluminium Matrix ◽  
Syntactic Foams ◽  
Drop Weight ◽  
Weight Impact

High Strain Rate Behavior of Carbon Nanotubes Reinforced Aluminum Foams

2017 ◽  
Vol 140 (1) ◽  
Author(s):  
Abdelhakim Aldoshan ◽  
D. P. Mondal ◽  
Sanjeev Khanna
Keyword(s):  
Carbon Nanotubes ◽  
Strain Rate ◽  
Aluminum Foam ◽  
High Strain ◽  
Split Hopkinson Pressure Bar ◽  
Dynamic Compression ◽  
Strain Rates ◽  
Aluminum Foams ◽  
Static Compression ◽  
Closed Cell

The mechanical behavior of closed-cell aluminum foam composites under different compressive loadings has been investigated. Closed-cell aluminum foam composites made using the liquid metallurgy route were reinforced with multiwalled carbon nanotubes (CNTs) with different concentrations, namely, 1%, 2%, and 3% by weight. The reinforced foams were experimentally tested under dynamic compression using the split Hopkinson pressure bar (SHPB) system over a range of strain rates (up to 2200 s−1). For comparison, aluminum foams were also tested under quasi-static compression. It was observed that closed-cell aluminum foam composites are strain rate sensitive. The mechanical properties of CNT reinforced Al-foams, namely, yield stress, plateau stress, and energy absorption capacity are significantly higher than that of monolithic Al-foam under both low and high strain rates.

Effects of automated fiber placement defects on high strain rate compressive response in advanced thermosetting composites

2021 ◽  
pp. 002199832110420
Author(s):  
Alexander Trochez ◽  
Von Clyde Jamora ◽  
Richard Larson ◽  
K. Chauncey Wu ◽  
Dipankar Ghosh ◽  
...  
Keyword(s):  
High Strain Rate ◽  
Strain Rate ◽  
High Strain ◽  
Split Hopkinson Pressure Bar ◽  
Fiber Direction ◽  
Loading Conditions ◽  
Hopkinson Pressure Bar ◽  
Fiber Placement ◽  
Automated Fiber Placement ◽  
Pressure Bar

The effects of fiber tow gaps, overlaps, and folds on the compressive strength of a fiber-placed composite laminate under dynamic loading conditions are investigated in this work. These layup defects were placed in the 0° fiber direction within a 24-ply quasi-isotropic laminate with a [45/0/–45/90]3S stacking sequence. Different locations of the defect were considered, namely near the bottom (in the 2nd ply), middle (10th ply) and top (23rd ply) of the laminate. High-strain rate compression experiments were conducted on composite that are pristine and with embedded defects using a split Hopkinson pressure bar (SHPB). The results were used to determine the strength knockdown due to the local changes in ply morphology because of fiber bed compaction in the presence of a layup defect. The experimental results revealed the anisotropy of in-plane strength coinciding with the deposited defect orientation. No significant variations in the residual strength were observed regarding the location of the defect (i.e., bottom, middle, or top) within the laminate. A morphological analysis based on microtomography of the cured defects indicates that the sources of the strength knockdown are due to the 0° ply drop-off, fiber misalignment in the adjacent 90° and 45° degree plies and the resin-rich region formed at the corner of the tapered 0° ply, between +45° and –45° laminas. The present study indicates the increased role of local morphological ply variations on the strength of composites under high-strain rate loading conditions, which should be considered during composite design.

scholarly journals Compressive Properties and Energy Absorption Characteristics of Extruded Mg-Al-Ca-Mn Alloy at Various High Strain Rates

Materials ◽  
2020 ◽  
Vol 14 (1) ◽  
pp. 87
Author(s):  
Chongchen Xiang ◽  
Zhendong Xiao ◽  
Hanlin Ding ◽  
Zijian Wang
Keyword(s):  
High Strain Rate ◽  
Strain Rate ◽  
Energy Absorption ◽  
High Strain ◽  
Split Hopkinson Pressure Bar ◽  
Extrusion Direction ◽  
Rate Sensitivity ◽  
Hopkinson Pressure Bar ◽  
Deformation Ability ◽  
Absorption Characteristics

This paper is focused on the mechanical properties and the energy absorption characteristics of the extruded Mg-Al-Ca-Mn alloy in different compression directions under high strain rate compression. Compressive characterization of the alloy was conducted from the high strain rate (HSR) test by using a Split Hopkinson Pressure Bar (SHPB). Results show that the investigated alloy exhibits a strong strain rate sensitivity. With the rise of strain rate, the compressive strength is increased significantly, and the deformation ability also improves. When compressed along the extrusion direction, as the strain rate increases, the total absorbed energy E, the crush force efficiency (CFE), and the specific energy absorption SEA of Mg-Al-Ca-Mn alloy are all greatly improved as compared with those obtained along other compression directions.

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