A plastic damage model for finite element analysis of cracking of silicon under indentation

2010 ◽  
Vol 25 (11) ◽  
pp. 2224-2237 ◽  
Author(s):  
Haibo Wan ◽  
Yao Shen ◽  
Qiulong Chen ◽  
Youxing Chen

A modified plastic damage model that accounts for tensile damage and compressive plasticity as well as interactions among them is adopted to simulate the indentation-induced cracking of silicon under Berkovich, cube corner, and Vickers indenters. Simulations with this model capture not only the well-known cracking geometries in indented ceramics, such as radial, median, lateral, and half penny (Vickers indenter) cracks, but also the recent experimentally discovered quarter penny cracks under Berkovich and cube corner pyramidal indenters. The quarter penny cracks are found to be formed by the coalescence of radial and median cracks for the first time in the simulation. Loads at which radial and half penny cracks are initiated in silicon are generally close to the experimental values reported in the literature, and the crack lengths on the sample surface agree well with both the current experimental measurements and analytical results by fracture mechanics.

2015 ◽  
Vol 815 ◽  
pp. 49-53
Author(s):  
Nur Fitriah Isa ◽  
Mohd Zulham Affandi Mohd Zahid ◽  
Liyana Ahmad Sofri ◽  
Norrazman Zaiha Zainol ◽  
Muhammad Azizi Azizan ◽  
...  

In order to promote the efficient use of composite materials in civil engineering infrastructure, effort is being directed at the development of design criteria for composite structures. Insofar as design with regard to behavior is concerned, it is well known that a key step is to investigate the influence of geometric differences on the non-linear behavior of the panels. One possible approach is to use the validated numerical model based on the non-linear finite element analysis (FEA). The validation of the composite panel’s element using Trim-deck and Span-deck steel sheets under axial load shows that the present results have very good agreement with experimental references. The developed finite element (FE) models are found to reasonably simulate load-displacement response, stress condition, giving percentage of differences below than 15% compared to the experimental values. Trim-deck design provides better axial resistance than Span-deck. More concrete in between due to larger area of contact is the factor that contributes to its resistance.


Author(s):  
Varatharajan Prasannavenkadesan ◽  
Ponnusamy Pandithevan

Abstract In orthopedic surgery, bone cutting is an indispensable procedure followed by the surgeons to treat the fractured and fragmented bones. Because of the unsuitable parameter values used in the cutting processes, micro crack, fragmentation, and thermal osteonecrosis of bone are observed. Therefore, prediction of suitable cutting force is essential to subtract the bone without any adverse effect. In this study, the Cowper-Symonds model for bovine bone was developed for the first time. Then the developed model was coupled with the finite element analysis to predict the cutting force. To determine the model constants, tensile tests with different strain rates (10−5/s, 10−4/s, 10−3/s, and 1/s) were conducted on the cortical bone specimens. The developed material model was implemented in the bone cutting simulation and validated with the experiments.


2015 ◽  
Vol 809-810 ◽  
pp. 235-240
Author(s):  
Catalina Maier ◽  
Robin Gauthier

Roller leveling is a forming process which used to minimize flatness imperfection and residual stresses by repeated forming process of a sheet metal. The determination of the machine settings must be very accurate and ask a precise mechanical study. In order to determine an algorithm which can predict the leveling quality according to the machine settings we start by a theoretical model of stress evolution during the process. The plastification ratio is deducted from this one and the values obtained by this approach are compared whit experimental values. The finite element analysis is performed, in second step in order to assure a good accuracy of the prediction algorithm. Theoretical study determines a minimum of the plastification ratio according to the machine settings. The finite element analysis gives more accurate results due to the consideration of different characteristics of the process, neglected by the theoretical model: cumulative effect of bending/unbending with stretching of the sheet during the passing between each couple of rolls, boundary conditions at the limit of the material deformed by two adjoining couples of rolls, friction force.


Author(s):  
Minh-Quy Le ◽  
Jin-Woo Yi ◽  
Seock-Sam Kim

Spherical indentation problems of ceramic coatings/metallic inter-layer/ductile substrate were investigated numerically by axisymmetric finite element analysis (FEA) for two typical ceramic coatings with relatively high and low elastic modulus deposited on aluminum alloy and carbon steel. Various indenter radius-coating thickness ratios and interlayer thickness-coating thickness ratios were used in the modeling. Radial stress distribution and plastic damage zones evolution were discussed in connection with model parameters. The results showed that the suitable metallic interlayer could improve resistance of ceramic coating systems through reducing the peak tensile radial stress on the surface and interface of ceramic coatings and plastic damage zone size in the substrate under spherical indentation.


2012 ◽  
Vol 184-185 ◽  
pp. 534-537
Author(s):  
Jing Jing Zhou ◽  
Ai Dong Guo ◽  
Chun Hui Li ◽  
Zhen Jiang Lin ◽  
Tie Zhuang Wu

By setting contact sets, achieved overall analysis results of the mechanical properties with omni-direction side-loading forklift truck lifting system based on COSMOSWorks. And made an experimental measurements to omni-direction side-loading forklift truck lifting system by electrometric methods. There was a good relevance between experimental data and calculation values, and the deviation was basically within the 10 percent allowed. Finally, in this way it verified the correctness and reliability of the finite element analysis by experimental measurements. Ensured the omni-direction side-loading forklift truck lifting system could be safe and efficient to work. And also it laid a foundation for subsequent structural optimization.


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