Conformal Contact Between a Rubber Band and Rigid Cylinders

2012 ◽  
Vol 79 (4) ◽  
Author(s):  
Takuya Morimoto ◽  
Hiroshi Iizuka

We consider a conformal contact problem between a rubber band and rigid cylinders that involves geometrical and material nonlinearities. The rubber band is assumed to be incompressible, neo-Hookean rubber. From the geometry and elasticity of the band, we present simple formulas to estimate the force–stretch relations and the contact pressure distributions on the cylinder. We show that the theoretical results are in good agreement with those of the finite element analysis when the rubber band is thin enough to be negligible to the bending stiffness. This verifies that the theory can effectively take into account both the material and geometrical nonlinearities of the band under the present conditions.

2013 ◽  
Vol 135 (2) ◽  
Author(s):  
Dianyin Hu ◽  
Rongqiao Wang ◽  
Guicang Hou

A new lifetime criterion for withdrawal of turbine components from service is developed in this paper based on finite element (FE) analysis and experimental results. Finite element analysis is used to determine stresses in the turbine component during the imposed cyclic loads and analytically predict a fatigue life. Based on the finite element analysis, the critical section is then subjected to a creep-fatigue test, using three groups of full scale turbine components, attached to an actual turbine disc conducted at 750 °C. The experimental data and life prediction results were in good agreement. The creep-fatigue life of this type of turbine component at a 99.87% survival rate is 30 h.


2014 ◽  
Vol 893 ◽  
pp. 314-319
Author(s):  
P. Gurusamy ◽  
S. Balasivanandha Prabu ◽  
R. Paskaramoorthy

This paper discusses the influence of die temperature on the solidification behaviour of A356/SiCp composites fabricated by squeeze casting method. Information on the solidification studies of squeeze cast composites is somewhat scarce. Experiments were carried out by varying the die temperatures for cylindrical shaped composite castings K-type thermocouples were interfaced to the die and the temperature-time history was recorded to construct the cooling curves. The cooling curves are also predicted from the finite element analysis (FEA) software ANSYS 13. The experimental and predicted cooling curves are not in good agreement. In addition to, the experimental and theoretical solidification times are studied. It was understood that the increase in the die temperature decreases the cooling rate.


1993 ◽  
Vol 115 (1) ◽  
pp. 102-109 ◽  
Author(s):  
S. A. Majlessi ◽  
D. Lee

The process of square-cup drawing is modeled employing a simplified finite element analysis technique. In order to make the algorithm computationally efficient, the deformation (total strain) theory of plasticity is adopted. The solution scheme is comprised of specifying a mesh of two-dimensional finite elements with membrane properties over the deformed configuration of the final part geometry. The initial positions of these elements are then computed by minimization of the potential energy, and therefore the strain distributions are determined. In order to verify predictions made by the finite element analysis method, a drawing apparatus is built and various drawing experiments are carried out. A number of circular and square cups are drawn and strain distributions measured. It is observed that there is generally a good agreement between computed and measured results for both axisymmetric and nonaxisymmetric cases.


2009 ◽  
Vol 23 (06n07) ◽  
pp. 1591-1596 ◽  
Author(s):  
YO-HAN JI ◽  
JONG-JIN PARK ◽  
CHANG-HO MOON ◽  
MYUNG-SHIK CHUN ◽  
HAE-DOO PARK

Plastic deformation that occurs in a heavy slab during plane-strain rolling was investigated by the finite element analysis. A cylindrical pore was assumed to be located along the transverse direction of a slab. The effective strain was found to be the largest at the sub-surface layer and the smallest at the middle layer, where the shear strain developed the least. Pore closure was most difficult at the middle layer. This is where hydrostatic stress in addition to effective strain developed the least. Rolling torques, rolling forces and pressure distributions at the roll/slab interface were investigated as well, under various conditions.


1992 ◽  
Vol 27 (3) ◽  
pp. 177-185 ◽  
Author(s):  
L S Ong ◽  
A K Soh ◽  
J H Ong

The problem of a local dent on a pressurized pipe is studied in this paper. Two case problems of dent are considered - a plain local dent (a smooth local dent without a surface defect), and a local dent associated with a loss of thickness defect. The strain gauging test and the finite element analysis on the plain local dent showed that the strain distributions in the local dent are different from those of a long and continuous dent. The maximum hoop strain in the local dent is located at the flank of the dent, along the dent axial axis, whereas in the case of the long dent, it is located at the root of the dent. In addition, the peak stress in the local dent is generally lower than that in the long dent. To estimate the stress concentration in the local dent using the analysis for the long dent would be grossly overestimated. The burst pipe tests on 17 dented pipes showed that the pipe failures were generally insensitive to the existence of the local dents. The pipe failures were found to be due to the loss-of-thickness defect. The comparison of results between the burst pipe tests and the plastic collapse formula shows reasonably good agreement.


2013 ◽  
Vol 648 ◽  
pp. 59-62
Author(s):  
Qi Yin Shi ◽  
Yi Tao Ge ◽  
Li Lin Cao ◽  
Zhao Chang Zhang

In this study, based on the test of the high strength materials of steel-encased concrete composite continuous beam, the ultimate flexural capacity of 8 composite continuous beams are analyzed by using the finite element analysis software ABAQUS. Numerical results show that it is a very good agreement for the load-deflection curves which obtained by finite element method (FEM) and those by the test results, and the error control is less than 8.5%. When selecting and utilizing appropriate cyclic constitutive model, element model and failure criterion of high strength steel and high strength concrete, the accuracy of the calculation can be improved better.


Author(s):  
Y B Park ◽  
D Y Yang

In metal forming, there are problems with recurrent geometric characteristics without explicitly prescribed boundary conditions. In such problems, so-called recurrent boundary conditions must be introduced. In this paper, as a practical application of the proposed method, the precision cold forging of a helical gear (which is industrially useful and geometrically complicated) has been simulated by a three-dimensional rigid-plastic finite element method and compared with the experiment. The application of recurrent boundary conditions to helical gear forging analysis is proved to be effective and valid. The three-dimensional deformed pattern by the finite element analysis is shown, and the forging load is compared with the experimental load. The profiles of the free surface of the workpiece show good agreement between the computation and the experiment.


2018 ◽  
Vol 10 (6) ◽  
pp. 168781401878002 ◽  
Author(s):  
Wei-chen Lee ◽  
Chen-hao Zhang

The objective of this research was to investigate the effects of material models, element types, and boundary conditions on the consistency of finite element analysis. Two cantilever beams were used; one made of stainless steel SUS301 3/4H and the other made of polymer polyoxymethylene. The load–deflection curves of the two cantilever beams obtained by experiments were compared to those obtained by finite element analysis, where the material models—including bilinear, trilinear, and multi-linear—were used. Four element types—beam, plane stress, shell, and solid—were also employed with the material models to obtain the simulated load–deflection curves of the cantilever beams. It was found that bilinear material models had the stiffest behavior due to their overestimated yield strength. In addition, by applying a finite displacement to simulate the grip of the cantilever beams, the discrepancy between the simulated permanent set and the experimental set could be reduced from 80% to 5%. To sum up, both the selection of the material model and the setup of the boundary conditions are critical for obtaining good agreement between the finite element analysis results and the experimental data.


Author(s):  
Jiangyue Zhang ◽  
Narayan Yoganandan ◽  
Frank A. Pintar ◽  
Thomas A. Gennarelli

The objective of this study is to biomechanical quantify the intracranial displacement and pressure distributions associated with civilian projectiles to advance clinical understanding of the pathophysiological consequences of penetrating head injuries. A finite element head model was developed in an attempt to investigate the penetrating processes and brain injury mechanisms. Two geometrical shapes of projectiles (flat and pinpoint headed) were considered for penetration. They were modeled as rigid bodies (6.5 and 9 g) impacting at an initial velocity of 300 m/s. The head was modeled as a spherical skull with left and right hemispheres. Material properties and damage criteria for the skull and brain were based on literature. The penetration process was modeled with eroding contact surface method with LS-DYNA. Elements considered damaged were removed from further computation when the stress or strain reached their thresholds. Temporal displacement and pressure distributions are described. The effects of projectile type on the wounding pattern are discussed. The entry location responded with higher magnitudes of displacement than other locations (e.g., exit, mid brain). The flat head projectile penetration resulted in higher magnitudes of pressure and displacement than the pinpoint projectile in the entire skull-brain system. The finite element analysis provides a quantitative understanding of the localized intrinsic responses secondary to projectile penetration.


Author(s):  
Guozhen Chen ◽  
Pinkuan Liu ◽  
Han Ding

Nonlinear static modeling is crucial for the design of stages with large travel ranges. However, few studies have investigated complex spatial compliant mechanisms. The present study proposes an optimization algorithm based on substructure constraint conditions to formulate the nonlinearity of the force–displacement characteristic of a tip-tilt-piston stage comprising leaf-spring flexure hinges. First, the nonlinear force–displacement characteristics of the compound basic parallelogram mechanism are derived using an optimization algorithm based on two constraint conditions (I and II). Second, the nonlinear static modeling of the tip-tilt-piston stage is conducted based on the modeling results of the compound basic parallelogram mechanism. The stage is divided into three parts, and force analyses are conducted for all three parts. The vertical displacement of the compound basic parallelogram mechanism in part 1 and the rotational angle of the rotational plate in part 2 are calculated. Subsequently, the force–displacement characteristics of the tip-tilt-piston stage are obtained based on a third constraint condition (III). A comparison of the finite element analysis results and the theoretical calculation indicates less than 4% errors. In the experimental tests conducted on the proposed stage and four compound basic parallelogram mechanisms, the displacements were evidently larger than those calculated using the finite element analysis. Therefore, a weight coefficient of the axial force w is introduced in the theoretical calculation to solve the problem of the large deviations between the experimental results and the finite element analysis results. When w is set to 1, the theoretical results are in good agreement with the finite element analysis results; when w is set to 0.05 for the tip-tilt-piston stage and 0.15 for compound basic parallelogram mechanisms, the theoretical results are consistent with the experimental results (less than 8.5% errors).


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