摘要 :
With a geometrical model of porous material, a 3D finite-element analysis on the rolling process of spring steel60Si2Mn in the semi-solid state is carried out using software MARC. In terms of flat and groove rolling conditions,str...
展开
With a geometrical model of porous material, a 3D finite-element analysis on the rolling process of spring steel60Si2Mn in the semi-solid state is carried out using software MARC. In terms of flat and groove rolling conditions,stress field and strain fiel
收起
摘要 :
In this paper, the finite element analysis software ( ANSYS ) is applied to the modal analysis of a ZJ30/1700CZ 's drilling machine derrick under a natural condition and a loaded condition, respectively. The preceding nine step na...
展开
In this paper, the finite element analysis software ( ANSYS ) is applied to the modal analysis of a ZJ30/1700CZ 's drilling machine derrick under a natural condition and a loaded condition, respectively. The preceding nine step natural frequencies and the corresponding mode shapes of the derrick are calculated. By means of the comparison of the natural frequency of the derrick with the design work frequency of the drilling machine and the analysis of the step mode shape of the derrick, the drilling machine derrick structure design is proved to be correct.
收起
摘要 :
AIM:To determine if rabbit models can be used to quantify the mechanical behaviour involved in tibial stress fracture(TSF)development.METHODS:Fresh rabbit tibiae were loaded under compression using a specifically-designed test app...
展开
AIM:To determine if rabbit models can be used to quantify the mechanical behaviour involved in tibial stress fracture(TSF)development.METHODS:Fresh rabbit tibiae were loaded under compression using a specifically-designed test apparatus.Weights were incrementally added up to a load of 30 kg and the mechanical behaviour of the tibia was analysed using tests for buckling,bone strain and hysteresis.Structural mechanics equations were subsequently employed to verify that the results were within the range of values predicted by theory.A finite element(FE)model was developed using cross-sectional computer tomography(CT)images scanned from one of the rabbit bones,and a static load of 6 kg(1.5 times the rabbit''''s body weight)was applied to represent running.The model was validated using the experimental strain gauge data,then geometric and elemental convergence tests were performed in order to find the minimum number of cross-sectional scans and elements respectively required for convergence.The analysis was then performed using both the model and the experimental results to investigate the mechanical behaviour of the rabbit tibia under compressive load and to examine crack initiation.RESULTS:The experimental tests showed that under a compressive load of up to 12 kg,the rabbit tibia demonstrates linear behaviour with little hysteresis.Up to 30 kg,the bone does not fail by elastic buckling;however,there are low levels of tensile stress which predominately occur at and adjacent to the anterior border of the tibial midshaft:this suggests that fatigue failure occurs in these regions,since bone under cyclic loading initially fails in tension.The FE model predictions were consistent with both mechanics theory and the strain gauge results.The model was highly sensitive to small changes in the position of the applied load due to the high slenderness ratio of the rabbit’s tibia.The modelling technique used in the current study could have applications in the development of human FE models of bone,where,unlike rabbit tibia,the model would be relatively insensitive to very small changes in load position.However,the rabbit model itself is less beneficial as a tool to understand the mechanical behaviour of TSFs in humans due to the small size of the rabbit bone and the limitations of humanscale CT scanning equipment.CONCLUSION:The current modelling technique could be used to develop human FE models.However,the rabbit model itself has significant limitations in understanding human TSF mechanics.
收起
摘要 :
The application of the finite layer & triangular prism element method to the 3D ground subsidence and stress analysis caused by mining is presented. The layer elements and the triangular prism elements have been alternatively used in the numerical simulation system, the displacement pattern, strain matrix, elastic matrix, stiffness matrix, load matrix and the stress matrix of the layer element and triangular prism element have been presented. By means of the Fortran90 programming language, a numerical simulation system based on finite layer & triangular prism element have been built up, and this system is suitable for subsidence prediction and stress analysis of all mining condition and mining methods. Comparing with the infinite element method, this approach dramatically reduces the size of the set of equations that need to be solved, and greatly reduces the amount of data preparation required. It not only saves the internal storage, and the computation time, but also decreases the cost....
展开
The application of the finite layer & triangular prism element method to the 3D ground subsidence and stress analysis caused by mining is presented. The layer elements and the triangular prism elements have been alternatively used in the numerical simulation system, the displacement pattern, strain matrix, elastic matrix, stiffness matrix, load matrix and the stress matrix of the layer element and triangular prism element have been presented. By means of the Fortran90 programming language, a numerical simulation system based on finite layer & triangular prism element have been built up, and this system is suitable for subsidence prediction and stress analysis of all mining condition and mining methods. Comparing with the infinite element method, this approach dramatically reduces the size of the set of equations that need to be solved, and greatly reduces the amount of data preparation required. It not only saves the internal storage, and the computation time, but also decreases the cost.
收起
摘要 :
Gears are pivotal in mechanical drives,and gear contact analysis is a typically difficult problem to solve.Emerging isogeometric analysis(IGA)methods have developed new ideas to solve this problem.In this paper,a threedimensional ...
展开
Gears are pivotal in mechanical drives,and gear contact analysis is a typically difficult problem to solve.Emerging isogeometric analysis(IGA)methods have developed new ideas to solve this problem.In this paper,a threedimensional body parametric gear model of IGA is established,and a theoretical formula is derived to realize single-tooth contact analysis.Results were benchmarked against those obtained from commercial software utilizing the finite element analysis(FEA)method to validate the accuracy of our approach.Our findings indicate that the IGA-based contact algorithmsuccessfullymet theHertz contact test.When juxtaposed with the FEA approach,the IGAmethod demonstrated fewer node degrees of freedomand reduced computational units,all whilemaintaining comparable accuracy.Notably,the IGA method appeared to exhibit consistency in analysis accuracy irrespective of computational unit density,and also significantlymitigated non-physical oscillations in contact stress across the tooth width.This underscores the prowess of IGA in contact analysis.In conclusion,IGA emerges as a potent tool for addressing contact analysis challenges and holds significant promise for 3D gear modeling,simulation,and optimization of various mechanical components.
收起
摘要 :
A new technology of knotless barbed surgical sutures has made its mark in cosmetic surgery around the world. Although this technology is still under development,it has been approved by the Federal Drug Administration in USA, and i...
展开
A new technology of knotless barbed surgical sutures has made its mark in cosmetic surgery around the world. Although this technology is still under development,it has been approved by the Federal Drug Administration in USA, and is now used for facelift and eyelid ptosis procedures. The objectives of this study were to review the different types of knotless sutures, assess the tissue holding capacity of barbed sutures and perform image analysis to better understand the mechanism of energy absorption by the barbs under loading by the forces of surrounding tissues. A two dimensional finite element analysis was also performed to identify the areas of stress concentration, which are the main precursors for the peeling of the barbs beyond the maximum tissue holding force for a particular polymer. It was found that barbed sutures exhibit tissue holding capacities comparable to that of knotted sutures. This technology needs to be investigated further so as to optimize the barb geometry for superior holding capacity in a variety of different tissues.
收起
摘要 :
Delamination and matrix cracking are two common failure mechanisms in composite structures,and are usually coupled with each other,leading to multiple failures pattern.This paper proposed a fast damage prediction methodology for c...
展开
Delamination and matrix cracking are two common failure mechanisms in composite structures,and are usually coupled with each other,leading to multiple failures pattern.This paper proposed a fast damage prediction methodology for composite laminated structures based on the ply-by-ply 2D(two dimensional)FE model of composite laminates in the transverse plane.The layer-wise 2D FE model was firstly used in conjunction with the integrated XFEM/CE strategy,which simulated the interface delamination with cohesive elements and the intra-ply matrix crack with XFEM(extended finite element method).To realize ply-by-ply 2D FE(finite element)modeling of composite laminates,two 2D material models were developed based on the plane stress assumption and plane strain assumption,respectively.A general crack propagation scheme was developed in the framework of the integrated XFEM-CE method.Adopting the 2D material model based on the plane strain assumption,a ply-by-ply discretized 2D FEA procedure was conducted for an out-of-plane composite Pi joint under the static tensile load.The predicted load-displacement response and damage evolution process showed good agreement with the experimental results,which verified the proposed approach.
收起
摘要 :
This study has focused on developing numerical procedures for the dynamic nonlinear analysis of cable structures subjected to wave forces and ground motions in the ocean. A geometrically nonlinear finite element procedure using th...
展开
This study has focused on developing numerical procedures for the dynamic nonlinear analysis of cable structures subjected to wave forces and ground motions in the ocean. A geometrically nonlinear finite element procedure using the isoparametric curved cable element based on the Lagrangian formulation is briefly summarized. A simple and accurate method to determine the initial equilibrium state of cable systems associated with self-weights, buoyancy and the motion of end points is presented using the load incremental method combined with penalty method. Also the Newmark method is used for dynamic nonlinear analysis of ocean cables. Numerical examples are presented to validate the present numerical method.
收起
