Mechanical Properties Of Different Materials Research Articles

Compressive Split Hopkinson Pressure Bar Apparatus: Part I - Design and Development

Optimum utilization of composite materials envisages its use under static as well as dynamic loading conditions. Hence, there is a need to assess the behavior of composite materials at high strain rates. Split Hopkinson Pressure Bar (SHPB) apparatus is widely used to assess high strain rate behavior of composites. Even though SHPB apparatus is widely used, its design methodology and development technique are not readily available. Design and devel- opment details of a compressive SHPB apparatus for characterizing mechanical properties of different materials at high strain rate loading are presented. Brief theoretical background necessary for the design of SHPB apparatus is presented based on one-dimensional wave propagation theory in elastic bars. Next, brief working principle of the apparatus and schematic arrangement are presented. Different components of the compressive SHPB appa- ratus are identified. Design, development and commissioning of the apparatus are discussed. Further, different instruments used and the calibration technique used are presented.

Peculiarities of using dumbbell specimens made of elastomeric materials subject to finite deformation in complex loading tests

The features of experiments with dumbbell specimens performed to determine the mechanical properties of filled elastomers are analyzed. Emphasis is placed on testing materials that experience a complex loading history. Experiments such as cyclic loading with increasing amplitude of deformations and with nested stress / strain cycles are considered. It has been established that the rate of change of the stretch ratio in the central part (gauge section) of the specimen significantly differs from that calculated from the analysis of the positions of the grips. This difference manifests itself more prominently in the experiments with complex loading algorithms. The reason is that the viscoelastic properties and the Mullins effect of the filled elastomer are different in the central part of the specimen and at its ends near the grips. The presence of inhomogeneous deformation in the gauge section leads to additional difficulties associated with finding constants for constitutive equations. Besides, this phenomenon complicates a comparison of the mechanical properties of different materials, because detailed information on their behavior can be obtained in complex experiments only. So, experiments with straight specimens or rings with a rectangular cross-section offer more possibilities for studying the mechanical properties of filled elastomers than the experiments with dumbbell specimens.

Evaluation of the mechanical properties of different materials for manufacturing occlusal splints.

This study aimed to compare the mechanical properties of various occlusal plate materials by analyzing surface roughness, Knoop microhardness, flexural strength, and modulus of elasticity. Fifty samples were prepared and classified as SC (self-curing acrylic resin), WB (heat-cured acrylic resin), ME (acrylic resin polymerized by microwave energy), P (resin print), and M (polymethylmethacrylate polymer block for computer-aided design/computer-aided manufacturing). The data were analyzed using a one-way analysis of variance and Tukey's honestly significant difference test. Surface roughness was the same in all groups. The surface hardness of group M was statistically superior. The samples from groups P and M had higher flexural strength than other samples. The modulus of elasticity of group SC was statistically lower than that of other groups. The mechanical properties of the materials used to make the occlusal plates differed, and group M achieved the best results in all analyses. Therefore, clinicians must consider the material used to manufacture long-lasting and efficient occlusal splints.

A Miniaturized Device Coupled with Digital Image Correlation for Mechanical Testing.

Miniaturized mechanical testing based on small sample testing technology is a powerful technique to characterize the mechanical properties of different materials, and it is being used in different application fields. However, the small size of the specimens poses several challenges because the results are highly sensitive to measurement accuracy and the corresponding mechanical properties can change substantially due to the so-called specimen size effect. In this work, a novel testing device based on miniaturized specimens is presented. The equipment is designed to test materials in tensile and compressive loadings, but it is also capable of performing reverse-loading tests. Buckling of the specimen is an inherent phenomenon in compression loadings, especially for thin materials. Therefore, specimen geometry is properly studied and optimized to mitigate this effect. To evaluate the deformation of the specimen, the digital image correlation (DIC) technique is used to capture the full-field strain in the central gauge section of the sample. A sensitivity analysis of the DIC setting parameters was performed for this application. To evaluate the performance of the developed system, experimental results of monotonic tests and tests with reverse loadings (tension-compression) are presented, considering two high-strength steels (DP500 and DP780).

Investigation of bending and compression properties on PLA-brass composite using FDM

Fused Deposition Modeling (FDM) is often favored over conventional techniques as it can produce highly accurate three-dimensional models with minimal material waste. Nevertheless, in FDM, the mechanical properties of different materials used in the FDM process are of ongoing interest. Since the properties of brass alloys in the FDM process are still lacking, the present study focuses on the bending and compression properties of the FDM printed part with 15 wt% and 70 wt% of brass-reinforced polylactic acid (PLA) and various infill patterns. The specimen preparation and testing were carried out accordingly to ASTM D790 and ASTM D695, respectively. The impact of five different infill patterns and two different compositions on the bending and compression properties was also analyzed using response surface methodology. A prediction model is then developed to predict the desired bending and compression properties. Results show that the 15 wt% of brass composition specimens have better properties compared with the 70 wt% of brass composition. This is due to an increase in the wt% of brass composition, which resulted in lower interlayer adhesion energy with the PLA. It was also found that the concentric and grid pattern are the best printing pattern for bending and compression properties, respectively.

Monte Carlo Simulation for Exploring Mechanical Properties of Porous Materials Based on Scaled Boundary Finite Element Method

The existence of pores is a very common feature of nature and of human life, but the existence of pores will alter the mechanical properties of the material. Therefore, it is very important to study the impact of different influencing factors on the mechanical properties of porous materials and to use the law of change in mechanical properties of porous materials for our daily lives. The SBFEM (scaled boundary finite element method) method is used in this paper to calculate a large number of random models of porous materials derived from Matlab code. Multiple influencing factors can be present in these random models. Based on the Monte Carlo simulation, after a large number of model calculations were carried out, the results of the calculations were analyzed statistically in order to determine the variation law of the mechanical properties of porous materials. Moreover, this paper gives fitting formulas for the mechanical properties of different materials. This is very useful for researchers estimating the mechanical properties of porous materials in advance.

Free surface energy evaluation in the laser texturing of a carbon steel s275

Currently, the manufacture of hybrid structures of dissimilar materials is generating great interest. These allow to combine mechanical properties of different materials to achieve a higher functional performance. To obtain these structures, different joining technologies are used, especially the use of adhesives. Nevertheless, for the correct application of an adhesive, the surface of the metal to be bonded must be prepared. Laser texturing has become a widely studied technology for this purpose because it allows very defined textures to be obtained. This technology allows to activate the surface and improve the application of the adhesive afterwards. In that sense, hydrophilic surfaces are generated and evaluated by wettability tests to know the surface free energy obtained in the texturing.In order to improve the bonding of dissimilar materials in the form of hybrid structure, a study has been carried out on the laser texturing of a carbon steel S275 and the relationship between the texturing parameters with its surface activation through wettability and surface free energy tests. Thus, the energy density obtained by the combination of power and scanning speed allows the generation of very defined textures that increase the surface activation of the steel. This has made it possible to establish a mathematical relationship between the texturing parameters and the results obtained.

Ionic Conductors: Effect of Temperature on Conductivity and Mechanical Properties and Their Interrelations

The ionic transport and the mechanical properties in solids are intimately related. However, few studies have been done to elucidate the background of that relation. With the objective to fill this gap and gain further understanding on the fundamental properties of ion conducting materials, we are studying systematically the mechanical properties of different materials. In the present study, after showing briefly our previous results obtained in crystalline materials, results regarding the relation between ionic conduction and mechanical properties in superionic glasses is presented. All these results indicate the intimate relation between the mechanical and ionic conduction. The results also indicate that the Grüneisen parameter and the Anderson–Grüneisen parameter of ionic conductors exhibit large temperature dependence and increase with temperature.

Research Progress of Cryogenic Materials for Storage and Transportation of Liquid Hydrogen

Liquid hydrogen is the main fuel of large-scale low-temperature heavy-duty rockets, and has become the key direction of energy development in China in recent years. As an important application carrier in the large-scale storage and transportation of liquid hydrogen, liquid hydrogen cryogenic storage and transportation containers are the key equipment related to the national defense security of China’s aerospace and energy fields. Due to the low temperature of liquid hydrogen (20 K), special requirements have been put forward for the selection of materials for storage and transportation containers including the adaptability of materials in a liquid hydrogen environment, hydrogen embrittlement characteristics, mechanical properties, and thermophysical properties of liquid hydrogen temperature, which can all affect the safe and reliable design of storage and transportation containers. Therefore, it is of great practical significance to systematically master the types and properties of cryogenic materials for the development of liquid hydrogen storage and transportation containers. With the wide application of liquid hydrogen in different occasions, the requirements for storage and transportation container materials are not the same. In this paper, the types and applications of cryogenic materials commonly used in liquid hydrogen storage and transportation containers are reviewed. The effects of low-temperature on the mechanical properties of different materials are introduced. The research progress of cryogenic materials and low-temperature performance data of materials is introduced. The shortcomings in the research and application of cryogenic materials for liquid hydrogen storage and transportation containers are summarized to provide guidance for the future development of container materials. Among them, stainless steel is the most widely used cryogenic material for liquid hydrogen storage and transportation vessel, but different grades of stainless steel also have different applications, which usually need to be comprehensively considered in combination with its low temperature performance, corrosion resistance, welding performance, and other aspects. However, with the increasing demand for space liquid hydrogen storage and transportation, the research on high specific strength cryogenic materials such as aluminum alloy, titanium alloy, or composite materials is also developing. Aluminum alloy liquid hydrogen storage and transportation containers are widely used in the space field, while composite materials have significant advantages in being lightweight. Hydrogen permeation is the key bottleneck of composite storage and transportation containers. At present, there are still many technical problems that have not been solved.

Fabrication and compression performance of continuous fiber Octet-truss lattice sandwich structure

Octet-truss is a three-dimensional lattice structure with light configuration and multi-function characteristics. In order to analyze and verify its compression resistance, a method of preparing Octet-truss lattice sandwich panel with continuous fiber was proposed. A set of Octet-truss structure molding tools was designed by this method. Different types of glass fiber and Kevlar fiber specimens were prepared by spatial weaving method and resin curing process, and the axial compression test was carried out. The experimental results show that the mechanical properties of different materials and different sizes of sandwich panels prepared by this method are stable, and the reliability of the preparation process is verified, Combined with the experimental process and electron microscope images, the main failure mode of glass fiber samples is fracture of the struts near the nodes induced by fiber microbuckling, while the Kevlar fiber samples failed by the Euler buckling of the struts.

Atmospheric corrosion of materials and their effects on mechanical properties: A brief review

Abstract The present study aims to review the atmospheric corrosion of engineering materials and their effects on the mechanical properties. There are various environmental factors which affect the atmospheric corrosion such as temperature, humidity, pollutants, particulate matter, oxygen, etc. The concentration and quality of these factors also vary from place to place. These influential factors which affect the atmospheric corrosion and the techniques associated to evaluate the corroded samples have been reviewed from the reported studies. Moreover, the influence of atmospheric corrosion on the mechanical properties such as tensile strength, fatigue has also been discussed. The discussion on surface morphology and rust analysis has also been revealed. It has been observed that the mechanical properties of different materials are highly influenced by atmospheric corrosion. This can be due to the increase in weight loss percentage in the corroded material that leads to diminish the properties. It has also been found that the high concentration of environmental factors and long-time exposure equally participate in the reduction of mechanical properties.

The effect of cryogenic treatment on dry sliding wear mechanisms in hard coatings

PurposeThe effect of cryogenic heat treatment on the mechanical properties of different materials has been frequently investigated by researchers in recent years. The purpose of this paper is to investigate wear behaviour of monolayer, multilayer and nanocomposite coatings after cryogenic heat treatment. It is a first in its field in terms of both the heat treatment used and the coatings examined.Design/methodology/approachThe aCN/TiAlN, TiAlN and ncTiAlSiN hard coatings deposited on the AISI D2 steel substrate were subjected to cryogenic heat treatment at −145oC and −196oC for 24 h and then tempered at 200oC for 2 h. Then, the samples were subjected to wear tests of 5, 10 and 15 N three different load values. The wear mechanisms occurring on the wear surfaces were determined by scanning electron microscope supported by EDS.FindingsOxidation, fatigue and delamination wear mechanisms were realized on the surfaces of the samples subjected to dry sliding wear test. The wear resistance of S1 increased with cryogenic heat treatment. According to the wear test results of the untreated samples, it was found that the samples with lower hardness than the others had higher wear resistance. The wear resistance of S1 and S2 samples was increased by cryogenic heat treatment. The best wear resistance in all parameters was obtained by S1. Oxidation in the S1 was found to have a positive effect on wear resistance. According to EDS results after wear of S2, chromium-rich layer was found on the surface of the material. It is understood that cryogenic heat treatment causes carbide precipitation in the inner structure of the substrate material.Originality/valueThe effect of cryogenic heat treatment on the mechanical properties of different materials has been frequently investigated by researchers in recent years. In this study, wear behaviour of monolayer, multilayer and nanocomposite coatings after cryogenic heat treatment was investigated. It is a first in its field in terms of both the heat treatment used and the coatings examined.Peer reviewThe peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-03-2020-0111/

Study of plastically deformed region underneath the ball in indentation tests and evaluation of mechanical properties of materials through finite element simulation and a hybrid algorithm

Ball indentation technique has been studied extensively in literature and it has been widely applied to determine mechanical properties of different materials because of simplicity and minimal requirement of material for the tests. Originally, the material deformation was represented in terms of a representative strain, which is a non-dimensional form of indentation diameter and a representative stress, which again is the instantaneous mean pressure multiplied by some empirical factors. It is known that the state of deformation as well as stress beneath the ball is multiaxial in nature in a ball indentation test. In this work, a new hybrid algorithm for estimation of equivalent stress and equivalent plastic strain during the process of indentation in the most stressed location beneath the ball has been developed. The algorithms uses experimental load–indentation data as well as the multiaxial stress and strain parameters obtained from 2D axisymmetric elastic-plastic finite element simulations. The stress and strain multiaxial parameters are functions of applied load, material yield stress and strain hardening exponents. The algorithm is iterative in nature and uses suitable initial guess values for material yield stress and strain hardening exponents and it converges very quickly. This method can be applied to determine the material stress–strain curve for a wide range of equivalent plastic strain, yield stress as well as plastic strain hardening exponent of the engineering materials. The data points of load vs. indentation depth as obtained directly from the ball indentation tests can be used in the new algorithm without the need for conducting unloading during the test. To illustrate the new scheme, two case studies have been presented where the results from the proposed new method have been compared with those of the existing method in literature and tensile test data to check the accuracy.

Development of bench top biaxial tensile testing machine

Development of new biaxial testing apparatus is carried out to study and evaluate the mechanical properties of different materials. Novel materials like biological tissue, soft plastics, fibers, wires, carbon nanotubes, smart materials, textiles, ceramics, composites etc. can be tested to evaluate its mechanical properties on the developed apparatus. The Developed apparatus will be used to evaluate mechanical properties. This apparatus will be used to characterize a material’s properties as a function of stain frequency, stress or a combination of these parameters. The equipment can be used to apply sinusoidal oscillating stress (load) which is applied to the specimen by actuators with the help of a servo controlled electric motors. The equipment has basic capabilities to produce static and cyclic multiaxial loading system. Generally, the test facility requires cruciform(Cross Shape) specimens which will be loaded orthogonal direction. Stress-controlled and strain controlled are two main techniques that are employed to test the specimen . As the stress-controlled analyzers are cheaper to manufacture (1) this technique will be adopted in the test rig. The test rig will be equipped with two mutually perpendicular actuators capable of incremental motions of as small as few microns. Each actuator will be equipped with a load cell to measure both tension and compression loads. The servo-electric actuators will be programmed to move independently or in a coordinated motion. Camera will be used to record and measure the strain produced in the specimen. Real world loading system can be created within the device to tests material capability in more realistic manner.

Effect of material mechanical differences on shear properties of contact zone composite samples: Experimental and numerical studies

Aiming at the mechanical and structural characteristics of the contact zone composite rock, the shear tests and numerical studies were carried out. The effects of the differences in mechanical properties of different materials and the normal stress on shear properties of contact zone composite samples were analyzed from a macro-meso level. The results show that the composite samples have high shear strength, and the interface of different materials has strong adhesion. The differences in mechanical properties of materials weakens the shear strength and increase the shear brittleness of the sample, while normal stress will inhibit these effect. Under low/high normal stress, the sample show two failure modes, at the meso-damage level: elastic-shearing-frictional sliding and elastic-extrusion wear. This is mainly controlled by the contact and friction state of the material after damage. The secondary failure of undulating structure under normal-shear stress is the nature of extrusion wear, which is positively correlated to the normal stress and the degree of difference in mechanical properties of different materials. The increase of the mechanical difference of the sample will enhance the shear brittleness under lower normal stress and the shear interaction under higher normal stress.

Laser polishing of 3D printed metallic components: A review on surface integrity

3D Printing is an emerging technology to fabricate complex components in less lead time compared to traditional manufacturing processes. 3D printing enables to build metallic functional components directly from CAD model by depositing the material layer by layer. The fabricated components generally have very rough surfaces and demands for post processing, so that it can directly employ for its end use. Owing to drawbacks like time consuming, skilled labour requirement and limited scope of automation, conventional finishing processes find less application for finishing freeform components. Laser Polishing is a highly productive, contactless and fully automatic post processing technique which is giving promising results to lower the surface roughness of 3D printed metallic components from the past two decades. In laser polishing, when the components are irradiated by the laser radiation, peaks of the surface are melted to a very thin layer and redistributed into the valleys by surface tension and gravity. Laser polishing has shown its ability to polishing varieties of materials from reflective materials like aluminium to high strength materials like Inconel and Titanium alloys. In this present article, a review of laser interaction on surface integrity and mechanical properties of different materials used in metallic 3D printing are reported. The optimum process parameters of laser polishing like laser power, beam diameter, scanning speed and scan spacing/step over are also mentioned with respect to each material.

Materials surface damage and modification under high power plasma exposures

Influence of powerful plasma impacts on several materials used for the construction of energy systems, i.e. different grades of steels as well as tungsten coatings, has been discussed. Irradiations of these materials with hydrogen and helium plasma streams have been performed in several high-current-pulse and quasi-stationary plasma accelerators which provided the variation of a power load upon the exposed surface as well as changes of the particle flux in wide ranges: the energy flux density in the range of 1-25 MJ/m2, particle flux - up to 1026-1029 ion/m2s, the plasma stream velocity - up to about 500 km/s, and the pulse duration in the range of 1-250 μs.A response of the investigated materials to extreme plasma loads, which are relevant to transient events in fusion reactors, is briefly discussed. It is demonstrated that a broad combination of mechanisms of powerful plasma interactions with various materials includes not only a surface damage caused by different erosion mechanisms, but under certain conditions it may also result in a significant improvement of material properties in the near-surface surface layer of several tens-μm in thickness. Some improvement of the structure and substructure of such a layer may be caused by the high-speed quenching, the shock wave formation and material alloying with plasma- and coating-species. The creation of unique surface structures and a considerable improvement of physical and mechanical properties of different materials can be achieved by the pulsed plasma alloying, i.e. pre-deposited coating modifications and mixing caused by the impacting plasma streams.

Mechanical property research of different materials for supporting rings.

Supporting rings are becoming more widely applied as an assistant structural support. However, during the engineering design and optimization process, many tests are necessary to understand the mechanical properties of different materials and the different section shape for supporting rings. The key problem is to measure the radial force caused by elongation under the axes' pressure. This cannot be measured directly through the use of sensors. The previous, simple method was to position a transfer bar into the hole on the supported wall, or use a strain gauge, which changes the contact boundary. A new method called the "semi-ring method" is proposed. The problem can be solved well and the feasibility of this method is shown from an example of its application. An innovative method is applied in test of mechanical performance for PTFE and butyl rubber material adopted in four kinds of section shape structure supporting rings. The results and analysis can provide some beneficial references for structure design.

Optimization of welding parameters for DP600/TRIP800 dissimilar joints

Abstract The widespread application of resistance spot welding in automotive body assemblies has made it mandatory for automotive manufacturers to examine the quality of the welding. A variety of destructive and nondestructive tests are applied and the weld nugget size is examined for inspection for weld quality. Because of the wide variety of welding parameters used in the spot welding, a welding diagram which gives the optimum weldability range for the welded material is required and extensively used. Due to the different chemical, physical and mechanical properties of different materials in dissimilar joints, it is difficult to evaluate the quality of the weld. In this study, the DP600/TRIP800 dissimilar steel couple was joined using resistance spot welding by combining various welding parameters including welding current, welding time and electrode force. The tensile shear test was applied for determining relationship between welding parameters and mechanical properties of weldment. For quality inspection, the weld nugget size and microstructure of welded sample was examined metallographically and the welding diagram dedicated to the optimum weldability range was also developed for dissimilar joints.

Mechanical and hygrothermal behavior of clay – Sunflower (Helianthus annuus) and rape straw (Brassica napus) plaster bio-composites for building insulation

The purpose of this study was to compare thermal and mechanical properties of different materials based on vegetal aggregates and clay in order to characterize the performances of four different biocomposites with a view to valorizing agricultural waste. The samples analyzed were manufactured with four different plant-based aggregates (rape straw, sunflower bark, sunflower pith and a mix of sunflower pith and bark) at a same binder/aggregate ratio. These materials revealed a wide range of densities and thermo-mechanical properties. As expected, increasing the material’s density gave a higher compressive strength while at the same time increasing thermal conductivity.