Finite Element Simulation of Inhomogeneity and Anisotropy of Proximal Femur

To solve implant's looseness and subsidence, and to adapt for the requirement of custom-made hip endoprostheses' rapid automatic design and manufacture, a new method is presented for constituting the anisotropic and inhomogeneous model of proximal femur based on CT, CAD technology and finite element analysis during design of custom-made hip endoprostheses, Raw CT image data, 3-D modeling and finite element software is utilized to set up 3-D finite element model of proximal femur. The model is provided with anisotropy and inhomogeneity by self-developed specific software. The near true proximal femur model is structured and good biomechanics condition is provided for optimize design of custom-made hip endoprostheses. For simulating and analysing of proximal femur's structrue and material mechanics property, and determining stress ,strain and response after-operation under the action of physiological load more exactly, and supplying design of custom-made hip endoprostheses with data, the method can provide biomechanics condition for optimize design of custom-made hip prostheses.     

Finite Element Simulate Analysis of Small Span-to Depth Ratio Coupling Beams with Special Reiforcement

Test investigations show that the reinforcement scheme with adding diagonal and rhombic bars to traditional reinforcement in the foundation is an ideal way, for the seismic performance of small span-to depth ratio coupling beams with this scheme is better than that of traditional reinforcement. Because the regions in the small aspect ratio coupling beam belong to D-regions, in which the Bernoulli hypothesis of plane strain distribution is invalid, the traditional bending theory can not be used. This paper simulates the coupling beam through non-linear finite element analysis program, and contrasts the analysis result of the bar's stress distribution with test result. The contrast results confirm that it is a valid way to analyse the bar's stress distribution in this coupling beam through non-linear finite element analysis program.     

Galerkin Approximate Solutions of Displacement Including the Effect of Dead Loads for Two Kinds of Rectangular Plates

Based on the strain energy considering the effect of dead loads, the general form static equilibrium differential equations were formulated by means of the potential energy principle. The approximate solutions of live load or later load displacement including the effect of dead loads for the clamped rectangular plate and the simply supported rectangular plate were generated by the Galerkin method. These formulas are simple and clear, and their physical concepts are explicit. The correctness of these formulas was verified by the finite element method. The dead loads and other factors that influence the effect of dead loads are shown by these formulas. The effect of dead loads on the two different boundary condition rectangular plate were analyzed by these approximate solutions. The effect of dead loads improves the bending stiffness of plate and minimizes the displacement of live loads or later loads. The key physical factors governing the effects of dead loads on plates are the dead load, the ration of span to thickness and boundary condition etc. This effect of dead loads is not negligible, especial in thinner plates or plates with smaller stiffness, more attention should be paid to the effect of dead load in the calculation and analysis for plates.     

Intensity Comparative Analysis Based on Ideas Between Involute Gear and Double Involute Gear

Modeler and simulation modules in Ideas software are used to build the finite element models on involute gear and double involute gear with accurate tooth shape, and with the same design parameters and under the same loads, finite element contact analysis has been done. At last, the contact stress and bending stress on the two types gear transmission at the different meshing positions are solved out, and comparative analysis and study have been done. At the same time, that the ladder-shape tooth on the double involute gear how to influence contact stress and bending stress is emphatically analysed. All above offer the theoretical foundation that bring the double involute gear with ladder-shape tooth into the industry.     

Finite Element Analysis and Experimental Research on Pedestal of PC Beam for Light Railcar

In design of light railcar used freely supported beam, the cast steel pedestals will bear complex loads, which include weight, acceleration and wind, etc. Because of pedestals' peculiarity and complexity, the strength of the pedestals play an important role in safety of light railcar. So it's necessary to analyze their stress and deformation in order to insure safety of light railcar. Up to now, finite element analysis is still the most effective means. By studying cast steel pedestal with finite element method, 3-D finite element models of fixed and kinetic pedestals were built, and the loads and boundary condition of pedestals were analyzed. By means of finite element analysis software, the contact and von mises stresses were obtained and deformation were resolved. As a result of analysis, the tow of pedestal can fulfill requirement of use in light railcar, the contact stress and von mises stress are not exceeded limit stress strength of materials. There is enough static strength for the structures of pedestals. For verifying theoretical analysis result, the fatigue test was carried out, with examining the testing points locating on the pedestals, the stress and deformation data were measured. By comparing between theoretical analysis and test data, the experimental results show calculated and testing results can meet the case well which assure the reliability of finite element analysis. But in the result, there are differences in deformations of them. The reason may be that boundary conditions and loads are not same between analysis and experiment.     

Comparisons of Methods for In-Plane Bearing Capacity Calculation of Two-Hinged Parabolic Steel Arch Under Full-Span and Half-Span Loads

The internal force would vary largely with different load ratio for steel arches under combined full-span with half-span loads. However, most relevant formulas on in-plane stability capacity of steel arches were obtained by studying the stability under a single load. Thus, it lacks full considerations of the applicability of bearing capacity formulas under a combined full-span load with half-span load. To overcome this shortcoming, the two-hinged parabolic steel arch was used to compare the results of bearing capacity of arches with different load ratios, rise-span ratios and sections calculated by several methods, The method proposed in the current Chinese design specification of steel arch structure and the finite element method based on the perfect arch and the consistent imperfect arch were included. The results showed that the method in the specification for designing a steel arch would be conservative with a large ratio of the full-span load to the total loads while unsafe with a large ratio of the half-span load to the total loads.     

Simulation on crack growth of drill pipe with XFEM

Crack growth of drill pipe is a typical discontinuous problem. It is difficult to simulate with conventional finite element method and extended finite element method (XFEM) is developed in recent years for the problem. With the introduction of XFEM, the XFEM model of 5 inch drill pipe was proposed with different depth initial cracks under combined action between torque and tension. Based on the simulation, It is found that the smaller cracks is not easy to grow, whilst the crack of depth more than 2mm could grow under relatively lower external load and larger growth surface, eventually leads to pipe fracture failure. Through this simulation on crack growth of drill pipe, it is showed that the XFEM is appropriate in analysis of fracture failure.     

Strain rate effects on dynamic behavior of reinforcement concrete columns with various reinforcement ratio

The mechnical characteristics of concrete is sensitive to the strain rate and it is crucial to consider the effect of load rates on the behavior of reinforced concrete (RC) structures subjected to dynamic loads such as severe earthquakes. In this study, numerical simulations on the dynamic behavior of typical RC column specimens under dynamic loadings with different load rates were performed. Concrete constitutive model considering the strain rate effects proposed by the CEB code was employed with a fiber model to characterize the nonlinear strain rate dependent behavior of RC columns. The developed dynamic fiber element model was validated by comparing the simulated results of four RC column specimens with the fast loading test results. Results show that the developed fiber element model can predict the behavior of RC columns with acceptable accuracy. After valiating the proposed fiber elemen model considering the strain rate effect, the load carrying capacity of different RC columns with various longitudinal reinforcement ratios and volumetric stirrup ratios were simulated. Results show that the trends of the influences of longitudinal reinforcement ratios and volumetric stirrup ratios on the load carrying capacity of the RC columns under dynamic loadings are different.     

Non-linear finite element analysis based on the spatial catenary cables

According to the elastic catenary theory,this paper derives the spatial catenary cable element from the exact analytical expression,which is used for finite element analysis of the structure.It deduces the precise expression of two-node cable element tangent stiffness matrix and the tension of cable end.The equivalent node load of cable element is expressed by the total load algorithm,and the non-linear equation is solved by double Newdon-rapson method.The proposed non-linear semi-analytical finite element method based on spatial catenary cable element can take full account of the impact of non-linear geometry.The initial configuration and the internal forces on any directional spatial loads can be solved.The example shows that the calculation method is accurate and effective.     

AUTOMATIC MESH GENERATION SCHEME IN FINITE ELEMENT CONTACT ANALYSIS OF MESHING GEARS

In this Paper, a new automatic mesh generation scheme is present, which combine the teeth contact analysis with the modelling of finite element cotact analysis. This procedure is different from the ordinary auto - mesh - generation scheme. The presentation of this new procedure makes it possible to analyze the elastic contact problem of meshing gears by a finite element method.     

Deflection and Stress Analysis of a Pavement Slab under Temperature Gradient and Axial Loading Coupling

It has been established that a pavement slab will curl up if a temperature gradient exists across the depth of a slab. A negative temperature gradient causes the slab edge to curl up while a positive temperature gradient curls up the slab center. Temperature stress in slabs is induced by self-weight and other slab constraints. At present in P. R. China, the total stress considered in cement concrete pavement design includes the load stress plus the temperature stress, and only transverse cracking from bottom to top is considered for concrete pavement. Slab responses under axial loads and temperature gradient coupling are not included. We modeled a single slab with a frictionless interface between the slab and foundation using the finite element method. Slab deflection and stress were calculated under axial loads at different slab positions and negative or positive temperature gradient coupling. The calculated results show that the different conditions of axial loads and temperature gradient coupling will change the maximum tension and cause various types of cracks in a slab.     

Complex Variable Function Solution of Stress and Displacement of Surrounding Rock Buried Deep Horseshoe-Shaped Tunnel Excavation

An analytical solution was presented for the stresses and displacements around horseshoe-shaped tunnel using Cauchy integral method and Optimization theory in an elastic half-plane. Since the depth of a tunnel was larger than the size of the tunnel, gravity loads were simplified as uniform normal loads along far-field boundary. Finite element model was used to verify the accuracy of analytical solutions. Comparison between the results of numerical analysis by finite element method and those from the closed solutions indicates that the closed solution is reliable and applicable for the stress and displacement field around horseshoe-shaped tunnel tunnels at great depth.     

落锤冲击气囊施加均布动荷载的试验方法

在结构构件上施加均布冲击(爆炸)荷载一直是动力试验领域的难题。提出了一种落锤冲击气囊施加均布动荷载的试验装置,和一个双自由度弹簧阻尼冲击加载简化分析模型;给出了该模型的基本力学方程、边界条件和求解方法,并进行了有限元验证;建立了所提出冲击加载试验装置的精细化有限元模型,分析了构件上各受荷区域的荷载均布情况,验证了所提出装置的可行性。基于所建立的简化分析模型,讨论了刚度、荷载作用时间和阻尼比等关键参数,对构件上动荷载的影响,并给出了基本规律。计算结果表明,在选定合适的参数后,落锤冲击气囊试验装置能够较好地模拟构件上的均布动荷载,为实验室中进行爆炸冲击试验提供了一种可能。     

Numerical Simulation of Eelastoplastic Multi-scales Model for Casting Magnesium Alloy

To realize the transforms of stress and strain and obtain the multi-scale constitutive equation across micro/meso/macro scales.strain-stress curves for magnesium alloy(AM60) and magnesium matrix are carried out with the machine MTS.By means of mixture law,mechanical property of particle is obtained.Based on the character of magnesium alloy structure,the finite element model of unit-cell included complex micro-structures is carried out.Via finite element numerical simulation of magnesium alloy unit-cell,the methodology overcome the limitation of present analytical method.Finally the multi-scale constitutive equation has been used for the analysis of the tensile stress vs. strain curve for magnesium alloy.Results show satisfactory agreement between the stress vs strain curve by the present methodology and the experimental data for AM60.     

Finite Element Analyses of Spherical Node of Coal Pipeline System of Blast Furnace

The mechanical model of spherical node of coal pipelines of blast furnace is built. Its boundary conditions and loads are presented. Its finite element analyses are used for this structure. Its stress distributing rules are obtained and the security of this structure is evaluated.     

Study on Seismic Behavior of Edge Slab-column Connection

Under the action of lateral forces and vertical loads, the connection of reinforced concrete slab-column structure will not only transfer significant shear forces, but also unbalanced moment. As to the edge slab-column connection, even if there is no later force, it will also transfer unbalanced moment due to the asymmetry. Currently, most tests and studies focus on interior connections, but there are few tests or studies on edge slab-column connections. A relatively new type of shear reinforcement named shear-stud reinforcement was applied in edge column-slab connections and study on the seismic behavior of these connections was conducted. Tests and finite element analysis of three full-scale reinforced concrete edge slab-column connections subjected to gravity and unbalanced moment were completed in this paper, and main conclusions were as following: the bearing capacity, deformation capacity and seismic behavior of connections reinforced with shear-stud reinforcement are improved; deformation of specimens reinforced with shear-stud reinforcement could meet requirements of current codes; the performance of energy dissipating is as good as the common connections, and has reached the medium ductility level.     

Determination of Load Share between Gear Teeth with Contact Finite Element Method

The determination of load share between teeth is a complex problem in gear strength calculation. On the basis of contact finite element method this paper considers the production-assembly error as initial gap to get the finite element model which meets load share between teeth in gear meshing. Through calculating and comparing the result with that from ISO formula to get the load share between teeth which meets the requirements in actual usage.     

Parametrical Finite Element Modeling for Framed Structure Based on Patran Software

In order to use FEM for engineer to anlysis structures by inputing only the designing parameters, the parametrical finite element software of a framed structure is developed, which has the functions of automatically modeling, adding constraints and loads, showing the results by inputing the changeable parameters. The validity of the software is proved by actual example.     

Numerical simulation of contact problems in high pressure reciprocating pump systems

The cylinder bodies of reciprocating pumps easily fail from cracks due to complex external loads. Based on the working principle of reciprocating pumps, hydrodynamics, and a numerical method for surface to surface contact problems, a contact model involving a cylinder body, a valve base, and a valve pocket is established. Considering pressure fluctuation, flow pulsation, alternate loads, and the impact of the inlet and outlet valves, a finite element model for the complete system is established. Using this model, the contact state of the complete system is analyzed, and the stress distribution, contact state, contact stress distribution of the interface, and position of the weak part are obtained.     

Primary Study of Applicability of Plane-section Assumption of Shaped RC Columns

Adopting the element SOLID65 and LINK8 in the general finite element analysis software ANSYS and fiber model beam-column element based on finite element flexibility method respectively, the comparative analysis of the cross, L and T-shaped RC columns under compression, bending, shear and torsion with flange width-thickness ratio of 4:1 is carried out. The applicability of plane section assumption in the nonlinear analysis is discussed primarily, which shows that it is feasible on the whole for shaped RC columns with flange width-thickness ratio equal to or smaller than 4:1.