• Structural Engineering and Mechanics
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• v.57 no.6
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• pp.1143-1156
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• 2016

This paper presents a comparative study of finite element method (FEM) and analytical method for the plane problem of a layered composite containing an internal perpendicular crack in literature. The layered composite consists of two elastic layers having different elastic constants and heights. External load is applied to the upper elastic layer by means o a rigid punch and the lower elastic layer rests on two simple supports. Numerical simulations are realized by the world wide code ANYS software. Two dimensional analysis of the problem is carried out and the results are verified by comparison with solutions reported in literature. Main goal of the numerical simulation is to investigate the normal stress ${\sigma}_x$(0, y), stress intensity factors at the crack factor and the crack opening displacements.

• 한국공간정보시스템학회:학술대회논문집
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• 2004.05a
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• pp.222-229
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• 2004

This study purports to analyze equally stressed surfaces in tension-membrane structures through a geometrically nonlinear approach. It adopts the formulation of a 4-node quadrilateral isoparametric plane stress element considering the orthotropic characteristic of membrane textures. Tension structures, which include cables and tension membranes, such as a cable dome initially exhibit unstable conditions because no initial internal stiffness such as bending stiffness is present. Such a structural system requires prestressing to the tension members to attain a stable state. A tension-membrane structure retains a stable three dimensional curved surface as a structural shape. This analytical process for finding the geometry is referred to as Shape Finding Analysis. In order to assess the validity of this study, we examine equally stressed surfaces of saddle and catenary shape shell structures and carry out pertinent stress analyses

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.4
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• pp.559-566
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• 2003

In this study, we present a new highly accurate two-dimensional curved composite beam element. The present element, which is based on the Hellinger-Reissner variational principle and classical lamination theory, employs consistent stress parameters corresponding to cubic displacement polynomials with additional nodeless degrees to resolve the numerical difficulties due to the spurious constraints. The stress parameters are eliminated and the nodeless degrees are condensed out to obtain the (9x9) element stiffness matrix. It should be noted that the stacking sequences without transverse deformation to the load plane makes a two dimensional analysis of curved composite beams practically useful . Several numerical examples confirm the superior locking-free behavior of the present higher-order laminated curved beam element.

• Journal of Ocean Engineering and Technology
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• v.7 no.2
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• pp.103-113
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• 1993

X-ray diffraction analysis technique was used for the fatigue damage analysis and fatigue life prediction in Al 7075-T651 alloy. The tensile test, fatigue strength and fatigue crack propagation test with change of stress ratio were carried out. As a result, half-value breadth was increased with the plastic deformation in the specimen increasint at all test conditions. In particular, half-value breadth at the surface of the specimens fractured by fatigue was increased as stress intensity factor range and effective stress intensity factor range were increased. In addition, the good relationship between half-value breadty and diffraction pattern was shown.

• Structural Engineering and Mechanics
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• v.72 no.4
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• pp.455-468
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• 2019

The present article is aimed at studying the reflection phenomena of plane waves in a homogeneous, orthotropic, initially stressed magneto-thermoelastic rotating medium with diffusion. The enuciation is applied to generalized thermoelasticity based on Lord-Shulman theory. There exist four coupled waves, namely, quasi-longitudinal P-wave (qP), quasi-longitudinal thermal wave (qT), quasi-longitudinal mass diffusive wave (qMD) and quasi-transverse wave (qSV) in the medium. The amplitude and energy ratios for these reflected waves are derived and the numerical computations have been carried out with the help of MATLAB programming. The effects of rotation, initial stress, magnetic and diffusion parameters on the amplitude ratios are depicted graphically. The expressions of energy ratios have also been obtained in explicit form and are shown graphically as functions of angle of incidence. It has been verified that during reflection phenomena, the sum of energy ratios is equal to unity at each angle of incidence. Effect of anisotropy is also depicted on velocities of various reflected waves.

• Structural Engineering and Mechanics
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• v.44 no.1
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• pp.35-49
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• 2012

A series of fatigue test were carried out on scarfed lap joints (SLJ) using in airfoil siding to explore the effect of structural details, such as rows of rivets, lap angles, on its fatigue performance. Finite element (FE) analysis was employed to explore the effect of lap angle on load transfer and the stress evolution around the rivet hole. At last, the fatigue lives were predicted by nominal stress approach and critical plane approach. Both of the test results and predicted results showed that fatigue life of SLJ was remarkably increased after introducing lap angle into the faying surface. Specimen with the lap angle of $1.68^{\circ}$ exhibits the best fatigue performance in the present study.

• Journal of Theoretical and Applied Mechanics
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• v.2 no.1
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• pp.31-50
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• 1996

In this paper, a finite element analysis based on the local approach concept to fracture in the continuum damage mechanics is performed to analyze ductile fracture in two dimensional quasi-static state. First an isotropic damage model based on the generalized concept of effective stress is proposed for structural materials in the context of large deformation. In this model, the stiffness degradation is taken as a measure of damage and so, the fracture phenomenon can be explained as the critical deterioration of stiffness at a material point. The modified Riks' continuation technique is used to solve incremental iterative equations. Crack propagation is achieved by removing critically damaged elements. The mesh size sensitivity analysis and the simulation of the well known shearing mode failure in plane strain state are carried out to verify the present formulation. As numerical examples, an edge cracked plate and the specimen with a circular hole under plane stress are taken. Load-displacement curves and successively fractured shapes are shown. From the results, it can be concluded that the proposed model based on the local approach concept in the continuum damage mechanics may be stated as a reasonable tool to explain ductile fracture initiation and crack propagation.

• Journal of Acupuncture Research
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• v.23 no.3
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• pp.231-239
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• 2006

Functional medicine is a system which utilizes certain investigative and treatment methods that are primarily oriented toward the recognition of functional disorder. Functional disorders take place on an energetic plane. This plane is not capturable using our regular investigatory techniques, such as X -ray. ultrasound, computer tomography and laboratory analyses. The 7-zone-diagnostic system(VEGA-DFM 722 and ABR-2000, etc) is a diagnostic device Which applies pulse signals to predetermined bodily locations. Applying alternating positive and negative stress to tissues with positive and negative pulses first manifests itself as negative and positive wave forms. The skin has many functions as an organ. It is the organism's interlace with the outsider world. Hence, the manner in which the skin reacts to external stimuli reflects the current state of the organism(as meridian systems). This system make a diagnosis of functional disorder or some typical organic diseases include stress of the mind or the body, and the energetic situation, reserves. We are known a disorder or disease throw the result chart. This result chart contain disorder flow wave forms and some valuable diagnostic hints (letters ; S, OM, RA, etc). In spite of this 7-zone-diagnostic system that is applied plentifully in the clinical application, there is not a statistics which is suitable. Therefor we must carry out many various research in the future.

• Steel and Composite Structures
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• v.33 no.4
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• pp.537-550
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• 2019

Korea and Japan have done a lot of research on composite girders with corrugated steel webs and built many bridges with corrugated steel webs due to the significant advantages of this type of bridges. Considering the demanding on the calculation method of such types of bridges and lack of relevant reinforcement design method, this paper proposes the spatial grid analysis theory and tensile stress region method. First, the accuracy and applicability of spatial grid model in analyzing composite girders with corrugated steel webs was validated by the comparison with models using shell and solid elements. Then, in a real engineering practice, the reinforcement designs from tensile stress region method based on spatial grid model, design empirical method and specification method are compared. The results show that the tensile stress region reinforcement design method can realize the inplane and out-of-plane reinforcement design in the top and bottom slabs in bridges with corrugated steel webs. The economy and precision of reinforcement design using the tensile stress region method is emphasized. Therefore, the tensile stress region reinforcement design method based on the spatial grid model can provide a new direction for the refined design of composite box girder with corrugated steel webs.

• Journal of Welding and Joining
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• v.28 no.1
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• pp.86-91
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• 2010

In the present study, two-dimensional plane deformation thermo elasto-plastic analysis has been carried out, in order to investigate the thermal and mechanical behaviour (residual stress, plastic strain, magnitude of stress and their distribution and production mechanism) on multi-pass FCA butt weldment of high strength EH36-TMCP ultra thick plate. Moreover, this study can be considered as a basis for analysing the fracture toughness, KIC, and its effect on welding residual stress redistribution with notch on multi-pass FCA butt weldment, in future. The results of welding residual stress obtained from thermo elasto-plastic analysis has been compared and verified with the results measured by XRD.