• Title/Summary/Keyword: von Mises plastic stress

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A study on the stress distribution and plastic area propagation in the beams with a circular hole (원형공을 가진 보의 응력분포와 소성역 전파거동에 관한 연구)

  • 김희철;왕지석;이경호
    • Journal of Advanced Marine Engineering and Technology
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    • v.9 no.3
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    • pp.225-239
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    • 1985
  • The beams with a circular hole are often used for constructing structures. The center of the circular hole is normally located in neutral axis and the stress state around the hole due to bending moment is trivial. But the stress level around the hole due to shear force is expected to be significant especially in the case of beams made of shape steels. In this paper, the stress distributions around the circular hole of beams were presented. Using polar coordinates and generallized stress function, the formulas of stress components were derived. The aspects of plastic area propagations based on von Mises yield criteria were also shown graphically. In order to verify the formulas presented in this paper, a beam of I-shape steel with a circular hole was made and the strains around the hole were measured under various loading conditions. The experimental results were proved to coincide fairly well with the calculated values.

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Application of Stress Optimization for Preventing the Delamination of the Plastic IC Package in Reflow Soldering Process (리플로 납땜과정에서 플라스틱 IC 패키지의 박리방지를 위한 응력최적설계의 적용)

  • Kim, Geun-Woo;Lee, Kang-Yong;Kim, Ok-Whan
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.28 no.6
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    • pp.709-716
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    • 2004
  • In order to prevent the interface delamination of an plastic IC package in the infrared (IR) soldering process, we tried to reduce stress by parameterization, sensitivity analysis and unconstraint optimization. The design variables of dimensions and material properties are determined among all the possible variables from the parametric study. Their optimized values are determined by applying the unconstraint optimization to the parameterized IC package. The maximum von-Mises stress value decreases greatly by optimum design.

Safety Evaluation for Restoration Process on Plastic Deformed Cylindrical Beam (소성변형된 실린더형 빔의 복원 안전성 평가)

  • Park Chi-Yong;Boo Myung-hwan
    • Journal of the Korean Society of Safety
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    • v.20 no.1 s.69
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    • pp.7-12
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    • 2005
  • In heavy industrial fields such as power plant and chemical plant, it is often necessary to restore a damaged part of large machinery or structure which is installed in the hazard working place. In this paper, to evaluate the safety of plastic deformed cylindrical beam a finite element technique has been used. The variations of residual stresses on the process of damaging and restoring for surfaces and cross-sections have been examined. The results show that the maximum von Mises stresses occur outer cylinder surfaces of boundary between cylindrical beam support md cylindrical beam when deformation procedure and restoring force is applied. The maximum residual stress remains 158.6MPa in the inner wall and this value correspond to $53\%$ of yield stress then restoration procedure is finished.

Stress analysis of rotating annular hyperbolic discs obeying a pressure-dependent yield criterion

  • Jeong, Woncheol;Chung, Kwansoo
    • Structural Engineering and Mechanics
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    • v.58 no.4
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    • pp.689-705
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    • 2016
  • The Drucker-Prager yield criterion is combined with an equilibrium equation to provide the elastic-plastic stress distribution within rotating annular hyperbolic discs and the residual stress distribution when the angular speed becomes zero. It is verified that unloading is purely elastic for the range of parameters used in the present study. A numerical technique is only necessary to solve an ordinary differential equation. The primary objective of this paper is to examine the effect of the parameter that controls the deviation of the Drucker-Prager yield criterion from the von Mises yield criterion and the geometric parameter that controls the profile of hyperbolic discs on the stress distribution at loading and the residual stress distribution.

Elastic-Plastic Finite Element Analysis of TiN Thin Film (TiN 박막의 탄소성 유한요소해석)

  • 김정실;김석삼
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • 2001.11a
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    • pp.331-340
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    • 2001
  • Elastic-Plasitc Finite element analysis is peformed about the TiN coated medium. The normal contact is simulated by a rigid asperity pressing the surface of an elastic-plastic half-surface. The case of a surface film stiffer than the substrate is considered, and general solutions for the subsurface stress and deformation fields are presented for several coating thickness. Additionally, the critical normal loads for deformation in the substrate and coating fracture are calculated when the yield of TiN film follows the Maximum Principal Stress Theory and Von Mises Theory. The results can be subsumed in failure maps for TiN thin film on steel.

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Effect of thermal gradients on stress/strain distributions in a thin circular symmetric plate

  • Aleksandrova, Nelli N.
    • Structural Engineering and Mechanics
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    • v.58 no.4
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    • pp.627-639
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    • 2016
  • The analysis of thermally induced stresses in engineering structures is a very important and necessary task with respect to design and modeling of pressurized containers, heat exchangers, aircrafts segments, etc. to prevent them from failure and improve working conditions. So, the purpose of this study is to investigate elasto-plastic thermal stresses and deformations in a thin annular plate embedded into rigid container. To this end, analytical research devoted to mathematically and physically rigorous stress/strain analysis is performed. In order to evaluate the effect of logarithmic thermal gradients, commonly applied to structures which incorporate thin plate geometries, different thermal parameters such as temperature mismatch and varying constraint temperature were introduced into the model of elastic perfectly-plastic annular plate obeying the von Mises yield criterion with its associated flow rule. The results obtained may be used in sensitive to temperature differences aircraft structures where the thermal effects on equipment must be kept in mind.

Residual stress in an elastoplastic annular disc interacting with an elastic inclusion

  • Zarandi, Somayeh Bagherinejad;Lai, Hsiang-Wei;Wang, Yun-Che;Aizikovich, Sergey M.
    • Coupled systems mechanics
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    • v.8 no.3
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    • pp.273-287
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    • 2019
  • Elastoplastic analysis of an annular disc, being fully constrained on its outer rim and interacting with a purely elastic inclusion perfectly bonded with its inner rim, is conducted to study its plastic deformation and residual stress under thermal cycles. The system is termed the composite disc. Quasi-static plane-strain deformation is assumed, and the von Mises yield criterion with or without the Ludwik hardening rule is adopted in our finite element calculations. Effects of multiple material properties simultaneously being temperature dependent on the plastic behavior of the composite disc are considered. Residual stress is analyzed from a complete loading and unloading cycle. Results are discussed for various inclusion radii. It is found that when temperature dependent material properties are considered, the maximum residual stress may be greater than the maximum stress inside the disc at the temperature-loaded state due to lower temperature having larger yield stress. Temperature independent material properties overestimate stresses inside materials, as well as the elastic irreversible temperature and plastic collapse temperature.

A New Algorithm for the Integration of Thermal-Elasto-Plastic Constitutive Equation (열탄소성 구성방정식 적분을 위한 새로운 알고리즘)

  • 이동욱;신효철
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.18 no.6
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    • pp.1455-1464
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    • 1994
  • A new and efficient algorithm for the integration of the thermal-elasto-plastic constitutive equation is proposed. While it falls into the category of the return mapping method, the algorithm adopts the three point approximation of plastic corrector within one time increment step. The results of its application to a von Mises-type thermal-elasto-plastic model with combined hardening and temperature-dependent material properties show that the accurate iso-error maps are obtained for both angular and radial errors. The accuracy achieved is because the predicted stress increment in a single step calculation follows the exact value closely not only at the end of the step but also through the whole path. Also, the comparison of the computational time for the new and other algorithms shows that the new one is very efficient.

Effects of thickness variations on the thermal elastoplastic behavior of annular discs

  • Wang, Yun-Che;Alexandrov, Sergei;Jeng, Yeau-Ren
    • Structural Engineering and Mechanics
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    • v.47 no.6
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    • pp.839-856
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    • 2013
  • Metallic annular discs with their outer boundary fully constrained are studied with newly derived semi-analytical solutions for the effects of thickness variations under thermal loading and unloading. The plane stress and axisymmetric assumptions were adopted, and the thickness of the disk depends on the radius hyperbolically with an exponent n. Furthermore, it is assumed that the stress state is two dimensional and temperature is uniform in the domain. The solutions include the elastic, elastic-plastic and plastic-collapse behavior, depending on the values of temperature. The von Mises type yield criterion is adopted in this work. The material properties, Young's modulus, yield stress and thermal expansion coefficient, are assumed temperature dependent, while the Poisson's ratio is assumed to be temperature independent. It is found that for any n values, if the normalized hole radius a greater than 0.6, the normalized temperature difference between the elastically reversible temperature and plastic collapse temperature is a monotonically decreasing function of inner radius. For small holes, the n values have strong effects on the normalized temperature difference. Furthermore, it is shown that thickness variations may have stronger effects on the strain distributions when temperature-dependent material properties are considered.

THE THREE DIMENSIONAL FINITE ELEMENT ANALYSIS OF THE STRESS DISTRIBUTION ACCORDING TO THE THREAD DESIGNS AND THE MARGINAL BONE LOSS OF THE IMPLANTS (임프란트 나사형태와 치조골 흡수에 따른 응력분산의 3차원 유한요소법적 분석)

  • Kim, Il-Kyu;Son, Choong-Yul;Jang, Keum-Soo;Cho, Hyun-Young;Baek, Min-Kyu;Park, Sheung-Hoon
    • Maxillofacial Plastic and Reconstructive Surgery
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    • v.30 no.1
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    • pp.60-71
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    • 2008
  • The objective of this study is to evaluate the stress distribution according to the thread design and the marginal bone loss of a single unit dental implant under the axial and offset-axial loading by three dimensional finite element analysis. The implants used had the diameter of 5mm and 4mm with 13mm in length and prosthesis with a conical type which is 6mm in height and 12mm in diameter. The thread designs were triangular, square and buttress. In the three dimensional finite element model with $15\times15\times20mm$ hexahedron and 2mm cortical thickness, implants were placed with crown to root ratio 7:12, 10:9, 13:6 and 16:3. And additionally the axial force of 100N were applied into 0mm, 2mm and 4mm away from the center of the implants. The results were as follows 1. The maximum von-Mises stress in cortical bone was concentrated to cervical area of implant, and in cancellous bone, apical portion. 2. Comparing the von-Mises stresses in cortical bone of 2mm and 4mm offset loading with central axial loading, it were increased to 3 and 5 times in diameter 4mm implant, and 2 and 4 times, in diameter 5mm implant. 3. The square threads were more effective than the triangular and butress as the longer diameter, the offset loading, and the worse crown to root ratio. 4. The von-Mises stresses were relatively stable until crown to root ratio 13:6, but it was suddenly increased at 16:3. From the results of this study, minimum requirement of crown to root ratio of implant is 2:1, and in the respect of crown to root ratio, diameter and offset loading, square threads are more effective than triangular and buttress threads.