scholarly journals Mechanical properties of nacre constituents and their impact on mechanical performance

2006 ◽  
Vol 21 (8) ◽  
pp. 1977-1986 ◽  
Author(s):  
François Barthelat ◽  
Chun-Ming Li ◽  
Claudia Comi ◽  
Horacio D. Espinosa
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Finite Element ◽  
Finite Element Model ◽  
Single Crystal ◽  
Elastic Properties ◽  
Mechanical Performance ◽  
Element Model ◽  
Compression Tests ◽  
Red Abalone

The mechanical properties of nacre constituents from red abalone were investigated. Electron microscopy studies revealed that the tablets are composed of single-crystal aragonite with nanograin inclusions. Both nanoasperities and aragonite bridges are present within the interfaces between the tablets. By means of nanoindentation and axial compression tests, we identified single tablet elastic and inelastic properties. The elastic properties are very similar to those of single-crystal aragonite. However, their strength is higher than previously reported values for aragonite. A finite element model of the interface accounting for nanoasperities and the identified properties revealed that the nanoasperities are strong enough to withstand climbing and resist tablet sliding, at least over the initial stages of deformation. Furthermore, it was observed that the model over-predicts strength and under-predicts ductility. Therefore, we conclude that other interface features must be responsible for the enhanced performance of nacre over its constituents.

The Effects of Operational, Testing and Material Characterisations On the Change in Yield Strength From Plate to Pipe

2021 ◽  
Author(s):  
Jingsi Jiao ◽  
Cheng Lu ◽  
Valerie Linton ◽  
Frank Barbaro
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Yield Strength ◽  
Finite Element Model ◽  
Mechanical Performance ◽  
Element Model ◽  
Critical Knowledge ◽  
Operational Testing ◽  
Wide Range ◽  
The Individual

Abstract The mechanical performance of the pipe sample has a direct influence on their application in real environments and a significant economic impact on manufacturers, especially when the pipe products do not meet required specifications. There is often a change in the yield strength from plate to pipe due to strain hardening and the Bauschinger effect. The current work sets out to provide a critical knowledge base for this change, with emphasizing the important influence of the plate mechanical properties on the pipe. So that the quality of pipe can be further ensured. In the work, firstly, the historical data of the pipe yield strength were collected and plotted together from a wide range of published sources to provide a broad quantitative insight, which provides a quantitative review on the parameters that govern the final pipe yield strength. Secondly, a Finite Element model of the pipe forming and mechanical evaluation was developed and then validated with available industrial testing results, in where the effects of operational and testing parameters on the pipe yield strength were analysed and discussed in detail. Finally, using the validated Finite Element model, a parametric study was conducted to dissect the individual role that each of the material parameters plays on changing the yield strength from plate to pipe. We found that the yield strength of the pipe can differ significantly. This work sheds lights on the desired plate mechanical properties to optimize the final pipe yield strength.

Finite Element Analysis of Mechanics Property on Memory Alloy Patella Claws with Anti-Shearing Force

2014 ◽  
Vol 635-637 ◽  
pp. 507-510
Author(s):  
Dong Peng Du ◽  
Zhe Wu ◽  
Juan Xing ◽  
Xiao Yan Gong ◽  
Xiang Wen Miu ◽  
...  
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Mechanical Performance ◽  
Tensile Force ◽  
Research Result ◽  
Element Model ◽  
3D Models ◽  
Shearing Force ◽  
Maximum Displacement ◽  
Element Analysis

When strong exercise on human being body, respectively, under knees 30°, 60°,90°, using PRO/E5.0 software to establish the transverse patella fracture and anti-shearing force patella claws 3D models, then the two structure models were assembled and imported into ABAQUS10.1 software to establish the finite element model of patellar fracture fixed within patella claw, and analyzed the mechanical performance in perforce finite element model. Under the same boundary conditions, the maximum displacement and deformation of each components were different at every flexion angle. Compared with anti-shearing force patella claw and AO tensile force girdle, the patella claw with stronger resistance to tension and anti-shearing force was more stable. Deformation and displacement of patella claw in accordance with biomechanical research result that is needed by clinical. Its stability will satisfy clinical requirements for functional exercise.

Finite Element Modeling of Selective Laser Melting 316L Stainless Steel Parts for Evaluating the Mechanical Properties

2016 ◽  
Author(s):  
Arman Ahmadi ◽  
Narges Shayesteh Moghaddam ◽  
Mohammad Elahinia ◽  
Haluk E. Karaca ◽  
Reza Mirzaeifar
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Stainless Steel ◽  
Finite Element Model ◽  
Grain Boundaries ◽  
Mechanical Response ◽  
Element Model ◽  
Polycrystalline Materials ◽  
Microstructural Properties ◽  
Laser Melting

Selective laser melting (SLM) is an additive manufacturing technique in which complex parts can be fabricated directly by melting layers of powder from a CAD model. SLM has a wide range of application in biomedicine and other engineering areas and it has a series of advantages over traditional processing techniques. A large number of variables including laser power, scanning speed, scanning line spacing, layer thickness, material based input parameters, etc. have a considerable effect on SLM process materials. The interaction between these parameters is not completely studied. Limited studies on balling effect in SLM, densifications under different processing conditions, and laser re-melting, have been conducted that involved microstructural investigation. Grain boundaries are amongst the most important microstructural properties in polycrystalline materials with a significant effect on the fracture and plastic deformation. In SLM samples, in addition to the grain boundaries, the microstructure has another set of connecting surfaces between the melt pools. In this study, a computational framework is developed to model the mechanical response of SLM processed materials by considering both the grain boundaries and melt pool boundaries in the material. To this end, a 3D finite element model is developed to investigate the effect of various microstructural properties including the grains size, melt pools size, and pool connectivity on the macroscopic mechanical response of the SLM manufactured materials. A conventional microstructural model for studying polycrystalline materials is modified to incorporate the effect of connecting melt pools beside the grain boundaries. In this model, individual melt pools are approximated as overlapped cylinders each containing several grains and grain boundaries, which are modeled to be attached together by the cohesive zone method. This method has been used in modeling adhesives, bonded interfaces, gaskets, and rock fracture. A traction-separation description of the interface is used as the constitutive response of this model. Anisotropic elasticity and crystal plasticity are used as constitutive laws for the material inside the grains. For the experimental verification, stainless steel 316L flat dog bone samples are fabricated by SLM and tested in tension. During fabrication, the power of laser is constant, and the scan speed is changed to study the effect of fabrication parameters on the mechanical properties of the parts and to compare the result with the finite element model.

Performance assessment of rigid polyurethane foam core sandwich panels under blast loading

2019 ◽  
Vol 11 (1) ◽  
pp. 109-130 ◽  
Author(s):  
Hosein Andami ◽  
Hamid Toopchi-Nezhad
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Polyurethane Foam ◽  
Sandwich Panel ◽  
Sandwich Panels ◽  
Element Model ◽  
Polyurethane Foams ◽  
Compression Tests ◽  
Foam Layer ◽  
The Finite Element Model

The performance of rigid polyurethane foams, as an energy absorbent core of sandwich panels covered with two exterior steel sheets, was investigated numerically through finite element methods. After verifying the finite element model, numerical studies were conducted to investigate the role of thickness and density of the foam layer in the response behavior of sandwich panels under blast loads. A set of cylindrical polyurethane foam specimens were manufactured at five different nominal densities, 90, 140, 175, 220, and 250 kg/m3, and their stress–strain curves were evaluated using uniaxial compression tests. The test data were then employed to define characteristics of the polyurethane foams in the finite element model. Based on the results of finite element analysis runs, the optimum density of the foam layer was determined by assessing two response parameters including the peak pressure transmitted to the back face of the foam layer and the maximum deflection of sandwich panel. These response parameters were found to be affected differently by variations in the density of the foam layer within the panel. An increase in the thickness of the foam layer, to a certain extent, was found to be beneficial to the mitigation capability of sandwich panel.

Research on the Shear Nails on the Arch Foot of an Oblique Cross Steel Box Arch Bridge

2013 ◽  
Vol 663 ◽  
pp. 49-54
Author(s):  
Xin Huang ◽  
Z.Z. Bai ◽  
De Wei Chen
Keyword(s):  
Finite Element ◽  
Shear Stress ◽  
Finite Element Model ◽  
Mechanical Performance ◽  
Maximum Shear Stress ◽  
Element Model ◽  
Bottom Up ◽  
Arch Bridge ◽  
Distribution Rules

In order to find the distribution rules on the shear nails on the steel-concrete composite segment of arch foot of an oblique cross steel box arch bridge, it established a space finite element model through the engineering of Wenzhou Weiwulu oblique cross steel box arch bridge, analyzing the maximum shear stress of the shear nails under normal using stage. The result shows that the welding nails in different position have a great difference in their shear stress. The welding nails which welded in a place that has a greater stiffness bear a bigger shear stress. So their mechanical performance of steel-concrete segment is better. In addition, the maximum shear stress becomes bigger from the bottom up to the top of the steel box.

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