scholarly journals On the Compressive Response of Polymeric Cellular Materials

Materials ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 457 ◽  
Author(s):  
Stefano Del Rosso ◽  
Lorenzo Iannucci
Keyword(s):  
Energy Absorption ◽  
Testing Machine ◽  
Dynamic Strength ◽  
Cellular Materials ◽  
Experimental Results ◽  
Strain Rates ◽  
Polymeric Foams ◽  
Compression Tests ◽  
Fe Method ◽  
Material Parameter Identification

This paper presents a series of compression tests performed on a variety of high performance lightweight cellular materials conventionally used in energy absorption applications. Compressive tests were performed over a range of strain rates with a universal testing machine and a single stage gas gun. Experimental results revealed a dependency of the mechanical properties on the polymeric precursor, density, infill topology and strain rates. The dynamic strength of the investigated materials was determined through a material parameter identification study via the finite element (FE) method. Numerical results matched well with the experimental results and revealed a substantial enhancement in the compressive strength of the tested material from quasi-static to dynamic loading regimes by as much as 87%. The strength of 3D printed polymers was superior with respect to the tested polymeric foams. On the other hand, polymeric foams showed higher efficiency and energy absorption ability.

Dynamic and Quasi-Static Compressive Deformation Behaviour of Polyimide Foam at Various Elevated Temperature

2014 ◽  
Vol 566 ◽  
pp. 158-163 ◽  
Author(s):  
A. Yosimoto ◽  
Hidetoshi Kobayashi ◽  
Keitaro Horikawa ◽  
Keiko Watanabe ◽  
Kinya Ogawa
Keyword(s):  
Compressive Strength ◽  
Room Temperature ◽  
Deformation Behaviour ◽  
Testing Machine ◽  
Negative Temperature ◽  
Strain Rates ◽  
Compression Tests ◽  
Hopkinson Pressure Bar ◽  
Universal Testing ◽  
Pressure Bar

In order to clarify the effect of strain rate and test temperature on the compressive strength and energy absorption of polyimide foam, a series of compression tests for the polyimide foam with two different densities were carried out. By using three testing devices, i.e. universal testing machine, dropping weight machine and sprit Hopkinson pressure bar apparatus, we performed a series of compression tests at various strain rates (10-3~103s-1) and at several test temperatures in the range of room temperature to 280 ̊C. At over 100 s-1, the remarkable increase of flow stress was observed. The negative temperature dependence of strength was also observed.

scholarly journals A Strain Rate-Dependent Damage Evolution Model for Concrete Based on Experimental Results

2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Bin Xu ◽  
Xiaoyan Lei ◽  
P. Wang ◽  
Hui Song
Keyword(s):  
Strain Rate ◽  
Uniaxial Compression ◽  
Damage Evolution ◽  
Damage Model ◽  
Evolution Model ◽  
Experimental Results ◽  
Strain Rates ◽  
Compression Tests ◽  
Stress Strain ◽  
Actual Damage

There are various definitions of damage variables from the existing damage models. The calculated damage value by the current methods still could not well correspond to the actual damage value. Therefore, it is necessary to establish a damage evolution model corresponding to the actual damage evolution. In this paper, a strain rate-sensitive isotropic damage model for plain concrete is proposed to describe its nonlinear behavior. Cyclic uniaxial compression tests were conducted on concrete samples at three strain rates of 10−3s−1, 10−4s−1, and 10−5s−1, respectively, and ultrasonic wave measurements were made at specified strain values during the loading progress. A damage variable was defined using the secant and initial moduli, and concrete damage evolution was then studied using the experimental results of the cyclic uniaxial compression tests conducted at the different strain rates. A viscoelastic stress-strain relationship, which considered the proposed damage evolution model, was presented according to the principles of irreversible thermodynamics. The model results agreed well with the experiment and indicated that the proposed damage evolution model can accurately characterize the development of macroscopic mechanical weakening of concrete. A damage-coupled viscoelastic constitutive relationship of concrete was recommended. It was concluded that the model could not only characterize the stress-strain response of materials under one-dimensional compressive load but also truly reflect the degradation law of the macromechanical properties of materials. The proposed damage model will advance the understanding of the failure process of concrete materials.

Plastic Flow Stress and Constitutive Model for H96 Brass Alloy

2015 ◽  
Vol 782 ◽  
pp. 130-136 ◽  
Author(s):  
Ping Zhou ◽  
Wei Guo Guo ◽  
Hai Hui Wu
Keyword(s):  
Flow Stress ◽  
Constitutive Model ◽  
Plastic Flow ◽  
Split Hopkinson Pressure Bar ◽  
Testing Machine ◽  
Experimental Results ◽  
Dynamic Strain ◽  
Strain Rates ◽  
Brass Alloy ◽  
Plastic Flow Stress

To explore the thermo-mechanical response of H96 brass alloy, the quasi-static (universal-testing machine) and dynamic (the split Hopkinson pressure bar apparatus) uniaxial compression experiments have been performed under the temperatures from 293 K to 873 K and the strain rates from 0.001 s-1 to 6000 s-1, and the strains over 60% are obtained. Results show that, H96 brass alloy has strong strain hardening behavior, and it becomes weaker with the increasing temperature. In addition, this alloy is sensitive to strain rates; and, it has temperature sensitivity, the dynamic strain aging occurs at the temperature of 473 K and a quasi-static strain rate of 0.001 s-1. Based on the thermal activation dislocation mechanism, paralleled with the experimental results, a plastic flow constitutive model with the physical conception is developed. The model is suitable to predict the plastic flow stress at different temperatures and strain rates. According to comparing results, the model predictions are in good agreement with the experimental results.

scholarly journals Plastic Dynamical Model for Bulk Metallic Glasses

Complexity ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-7
Author(s):  
Shaowen Yao ◽  
Zhibo Cheng
Keyword(s):  
Metallic Glasses ◽  
Loading Rate ◽  
Testing Machine ◽  
Compressive Loading ◽  
Shear Bands ◽  
Bulk Metallic Glasses ◽  
Experimental Results ◽  
Dynamical Model ◽  
Compression Tests ◽  
Rate Range

Based on previous experimental results of the plastic dynamic analysis of metallic glasses upon compressive loading, a dynamical model is proposed. This model includes the sliding speed of shear bands in the plastically strained metallic glasses, the shear resistance of shear bands, the internal friction resulting from plastic deformation, and the influences from the testing machine. This model analysis quantitatively predicts that the loading rate can influence the transition of the plastic dynamics in metallic glasses from chaotic (low loading rate range) to stable behavior (high loading rate range), which is consistent with the previous experimental results on the compression tests of a Cu50Zr45Ti5 metallic glass. Moreover, we investigate the existence of a nonconstant periodic solution for plastic dynamical model of bulk metallic glasses by using Manásevich–Mawhin continuation theorem.

Mechanical Behaviour and Energy Absorption Foam Filled Structures of Square Section under Compression Loading

2014 ◽  
Vol 592-594 ◽  
pp. 1109-1113 ◽  
Author(s):  
Dipen Kumar Rajak ◽  
L.A. Kumaraswamidhas ◽  
S. Das
Keyword(s):  
Energy Absorption ◽  
Mechanical Energy ◽  
Testing Machine ◽  
Aluminium Foam ◽  
Strain Rates ◽  
Universal Testing ◽  
Good Energy ◽  
Foam Filled ◽  
Steel Foam ◽  
Compressive Tests

The focus of this paper is to study the energy absorption characteristics of aluminium foam filled sections. The energy absorption capability of square mild steel foam filled and empty samples to absorbed mechanical energy have been estimated according to the results from the compressive tests. The tests were performed on the universal testing machine .The experimental results shows that aluminium foam filled sections feature have good energy absorption at various strain rates from 10-3/s to 10/s.

Hot Deformation and Processing Map of C919 Aluminum Alloy

2015 ◽  
Vol 816 ◽  
pp. 810-817
Author(s):  
Yong Biao Yang ◽  
Zhi Min Zhang ◽  
Xing Zhang
Keyword(s):  
Aluminum Alloy ◽  
Flow Stress ◽  
Strain Rate ◽  
Hot Deformation ◽  
Testing Machine ◽  
Strain Rate Range ◽  
Hot Compression ◽  
Strain Rates ◽  
Processing Maps ◽  
Compression Tests

The hot deformation behaviors of Aluminum alloy C919 were studied in the present investigation. The hot compression tests for C919 were carried out in the temperature range of 350°C~470°C and strain rates range of 0.001s-1~1s-1 using GLEEBLE-1500 thermal simulate testing machine. Optical microscopy (OM) was used for the microstructure characterization. The experimental results showed that the flow stress of C919 aluminum alloy decreased with increasing temperature and decreasing strain rates and the flow stress curves tended to increase at a strain rate of 1s-1 with increasing strain, while the flow stresses kept with increasing strain at lower strain rate. The alloys were more prone to dynamic recrystallization with decreasing strain rates during hot deformation. The hot compression behavior of C919 aluminum alloy can be described as hyperbolic sine function corrected Arrhenius relation. The processing maps for the alloy were built at a strain of 0.6. The instability deformation domain occurred at temperatures range from 350°C and 380°C and at a strain rate of 0.1-1s-1. Based on the processing maps and microstructure observations, the optimum hot-working parameters were determined to be at a temperature of 470°C in the strain rate range from 0.1-0.01s−1 for the C919 aluminum alloy.

Compression Tests of High Strength Steels

2008 ◽  
Vol 59 ◽  
pp. 293-298
Author(s):  
Vaclav Mentl ◽  
Josef Bystricky
Keyword(s):  
Mechanical Properties ◽  
Mechanical Testing ◽  
High Speed ◽  
Dynamic Compression ◽  
Testing Machine ◽  
High Strength Steels ◽  
High Strength ◽  
Strain Rates ◽  
Compression Tests ◽  
Impact Compression

Mathematical modelling and virtual testing of components and structures represent a useful and economic tool for design and safety assessment. The basic mechanical properties which can be found in material standards are not relevant in cases where the real service conditions differ from those applied during standardised testing. Thus e.g. mechanical behaviour at higher strain rates can be interesting for the car components when the simulation of crash situations is used during structure development. The dynamic compression tests are usually performed by means of drop towers, by means of high speed hydraulic testing machines or Hopkinson bar method. At the Mechanical Testing Laboratory of the SKODA Research Inst. in Pilsen, Czech Republic, an instrumentation of Charpy pendulum testing machine was realised in order that it was possible to perfom dynamic compression tests, [1], and the compatibility of obtained results in comparison with traditional impact compression tests was verified within the round–robin carried out by TC5 ESIS Sub-Committee on “Mechanical Testing at Intermediate Strain Rates“, [2]. A new striking tup and load measurement system were designed and callibrated. At the same time, a new software was developed which makes it possible to evaluate the test force-deformation record. The goal of this study was 1. to check the possibility of compression testing of high strength materilas by mens of Charpy pendulum, and 2. to study the strain rate influence on basic mechanical properties.

Dynamic Strain Aging Behavior of a Mg-Ce Alloy and its Implications for Extrusion

2012 ◽  
Vol 706-709 ◽  
pp. 1193-1198 ◽  
Author(s):  
Lan Jiang ◽  
John J. Jonas ◽  
Raja K. Mishra
Keyword(s):  
Dynamic Strain Aging ◽  
Rate Equation ◽  
Texture Component ◽  
Strain Aging ◽  
Experimental Results ◽  
Dynamic Strain ◽  
Strain Rates ◽  
Compression Tests ◽  
Aging Behavior

Compression tests were employed to characterize the DSA behaviour of Mg-Ce alloys. Samples were taken from cast billets and extruded bars of Mg-0.5 wt.% Ce. The DSA behavior was examined at temperatures from 150°C to 400°C at strain rates of 0.001/s to 1.5/s. A rate equation was fitted to the experimental results, which is employed to predict whether or not DSA will occur at the strain rates and temperatures involved in the formation of the RE texture component during extrusion.

scholarly journals An Experimental Study on Boron Carbide Reinforced Open Cell Aluminum Foams Produced via Infiltration Technique

2018 ◽  
Vol 8 (6) ◽  
pp. 3640-3645
Author(s):  
T. Sunar ◽  
M. Cetin
Keyword(s):  
Energy Absorption ◽  
New Technologies ◽  
Weight Ratio ◽  
High Energy ◽  
Cellular Materials ◽  
Absorption Capacity ◽  
Compression Tests ◽  
Aluminum Foams ◽  
Space Holder ◽  
B4c Particles

Light structures and parts are very effective for new engineering applications. Their considerably low densities, high energy absorption capabilities, and desirable mechanical properties make them useful for particularly automotive, defense and aerospace industries. Besides these positive properties, it is known that the production and processing of cellular materials is very tough and worth the effort. Recently, with advances in new technologies like 3D printing or selective laser melting, now different types of cellular materials can be produced. But manufacturing of metallic foams via casting especially replication or infiltration method is fairly an economic method when compared with other methods. In this study, vacuum-gas infiltration set-up was used to produce B4C reinforced aluminum foams. The mentioned method involves the addition of space holder materials and a dissolution technique to remove them after solidification of the metal. As space holder materials NaCl particles were selected and mixed with B4C powders to produce B4C reinforced A360 aluminum foam. By changing the weight ratio of B4C particles, the alteration of properties like porosity, compression strength, and energy absorption capacity was investigated. Additionally, computer tomography views were obtained to see and interpret the microstructures of the foams. Compression tests were carried out to evaluate the mechanical behavior of the foams under static loading. The porosities of samples obtained as between 65-75%. The compressive strength increased with rising relative density.

A Thermovisco-Hyperelastic Constitutive Model of NEPE Propellant Over a Large Range of Strain Rates

2014 ◽  
Vol 136 (3) ◽  
Author(s):  
Junfa Zhang ◽  
Jian Zheng ◽  
Xiong Chen ◽  
Chaoxiang Sun ◽  
Jinsheng Xu
Keyword(s):  
Mechanical Properties ◽  
Constitutive Model ◽  
Large Range ◽  
Testing Machine ◽  
Experimental Results ◽  
Strain Rates ◽  
Static State ◽  
Rate Dependent ◽  
Different Temperatures ◽  
Nepe Propellant

The uniaxial compressive mechanical curves of nitrate ester plasticized polyether (NEPE) propellant under different temperatures and strain rates have been obtained with a universal testing machine and modified split Hopkinson pressure bar (SHPB). The experimental results show that the mechanical properties of NEPE propellant are both rate dependent and temperature dependent. With decreasing temperature or increasing strain rate, the modulus and rigidity obviously increase. Based on the previous models proposed by Yang and Pouriayevali, we propose a modified viscohyperelastic constitutive model which can describe the mechanical response over a large range of strain rates. Then we add a rate-dependent temperature item into the modified model to make a thermovisco-hyperelastic constitutive model. By comparing the experimental results with the model, we find that the thermovisco-hyperelastic constitutive model can correctly describe the uniaxial compressive mechanical properties of NEPE propellant at different temperatures and over a large range of strain rates from the static state to 4500 s−1.

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