• Title/Summary/Keyword: elastic plastic deformation

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Determination of Elastic Recovery for Axi-Symmetric Forged Products (축대칭 단조공정에서 최종제품의 탄성회복에 관한 해석)

  • Kim, T.H.;Kim, D.J.;Park, J.C.
    • Journal of the Korean Society for Precision Engineering
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    • v.13 no.9
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    • pp.165-173
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    • 1996
  • The dimensional accuracy of a final product is mainly affected by elastic die deformation during the forging and elastic recovery after the ejection in cold forging process. The investigations on elastic recovery are not so much as those of elastic die deformation. The elastic recovery can be determined by using the elastic-plalstic finite element analysis, but, this method has some limits such as poor conver- gence and long computational time, etc. In this paper, a theoretical analysis for predicting the elastic recovery of a final product in axi-symmetric forging process by using the rigid-plastic finite element method is presented. The rigid-plastic finite element analysis of a cold forward extrusion process involving loading, ejecting process is accomplished by rigid-plastic FE code, DEFORM. The effect of elastic die deformation on the final product dimenmsion is also considered. The calculated elastic recovery is compared is compared with the analysis result of elastic-plastic FE code. ABAQUS.

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A Study on the Simulation of Welding Deformation for accurate Assembling (고정밀도 조립을 위한 용접 변형의 해석에 관한 연구)

  • Sung, Ki-Chan;Jang, Kyung-Bok;Jung, Jin-Woo;Kang, Sung-Soo
    • Journal of the Korean Society for Precision Engineering
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    • v.18 no.4
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    • pp.129-134
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    • 2001
  • It is essential to predict the welding deformation at assembly stage, to increase productivity through mechanization and automation effectively. A practical analysis method appled for production engineering was proposed to simulate the deformation of arc welding, with an analytical model using finite element method solving thermal-elastic-plastic behavior. In this research, for accurate assembling, 3-D thermal-elastic-plastic finite element model is used to simulate the out-of-plane deformation caused by arc welding. Efforts have been made to find out the efficient method to improve the reliability and accuracy of the numerical calculation. Each of theories of small and large deformation is applied in solving 3-D thermal-elastic-plastic problem to compare with their efficiency about calculation imes and solution accuracy. When solid elements are used in a bending problem of a plate, phenomenon that the predictive deformation is more than that of actual survey is observed. To prevent this phenomenon, reduced integration method for element is employed instead of full integration that is generally used in 3-D thermal-elastic-plastic analysis.

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Elastic-Plastic Fatigue Crack Growth and J Integral (彈塑性 疲勞균열進展과 J積分)

  • 송지호;김일현;박영조
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.8 no.1
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    • pp.26-33
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    • 1984
  • Constant-load-amplitude fatigue crack growth tests were carried out on 5083-0 aluminum alloy under elastic and elastic-plastic conditions. Crack length, crack closure and monotonic fatigue deformation were measured by Kikukawa's unloading elastic compliance monitoring technique and elastic-plastic fatigue crack growth rates were analysed in terms of J integral. Elastic-plastic fatigue crack growth rates can be well expressed by effective cyclic J integral until general yielding occurs. Beyond general yielding, monotonic fatigue deformation becomes significant and growth rates cannot be characterized by a single parameter of effective cyclic J integral alone. However, introducing one more parameter, maximum J integral J$_{max}$ to account for the effect of monotonic fatigue deformation, can explain fatigue crack growth behavior beyond general yielding.

A Study on the Expansive Deformation of Rifle Barrel and Gun Barrel (총열 및 포신의 팽창 변형에 관한 연구)

  • 김동욱;이재영;강영철
    • Journal of the Korea Institute of Military Science and Technology
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    • v.3 no.2
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    • pp.7-14
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    • 2000
  • In this paper, the possibility of plastic deformation of rifle and gun barrels is studied through the numerical methods. When a rifle or tank gun is fired, the expansive deformation of the barrel can occur by the explosive pressure and the thermal effect. Using the ABAQUS program, the stresses and displacements are computed for the elastic and elastic-plastic material property, and the possibility of plasticity deformation is investigated. In conclusion, rifle and tank gun barrel the plastic deformation occurred in some parts of the barrel

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A New Interpretation on the Additive and Multiplicative Decompositions of Elastic-Plasmic Deformation Gradient Tensor (탄소성 변형구배텐서의 가산분해와 곱분해에 대한 새로운 역학적 이해)

  • Y.Y. Nam;J.G. Shin
    • Journal of the Society of Naval Architects of Korea
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    • v.33 no.3
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    • pp.94-102
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    • 1996
  • An interpretation for the additive and multiplicative decomposition theory of the deformation gradient tensor in finite deformation problems is presented. the conventional methods have not provided the additive deformation velocity gradient. Moreover the plastic deformation velocity gradients are not free from elastic deformations. In this paper, a modified multiplicative decomposition is introduced with the assumption of coaxial plastic deformation velocity gradient. This strategy well gives the additive deformation velocity gradient in which the plastic deformation velocity gradient is not affect4d by the elastic deformation.

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Residual Stress Analysis in Bi-material Metal Joint under Bending Moment by Finite Element Method (이종재료 금속조인트의 굽힘에 의한 잔류응력 해석)

  • Baek Tae-Hyun;Jung Girl;Park Tae-Geun
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2005.10a
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    • pp.448-451
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    • 2005
  • It was observed that after unloading or removal of the load from the specimen subjected to bending stress, partial or full elastic spring back occurred and considerable stresses have resulted while plastic deformation was considered. ABAQUS is a suite of powerful engineering simulation programs, based on the finite element method. In this paper, it was used as the main tool to analyze elastic and plastic deformations of hi-material metal joint. In the case of elastic deformations, the results were comparable to the theoretical data. Plastic deformations and residual stresses of hi-material metal joint under bending moment were obtained by ABAQUS; where the theory needs to be studied and improved further to verify the results.

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Elastic-Plastic Implicit Finite Element Method Considering Planar Anisotropy for Complicated Sheet Metal Forming Processes (탄소성 내연적 유한요소법을 이용한 평면 이방성 박판의 성형공정해석)

  • Yun, Jeong-Hwan;Kim, Jong-Bong;Yang, Dong-Yeol;Jeong, Gwan-Su
    • Transactions of Materials Processing
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    • v.7 no.3
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    • pp.233-245
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    • 1998
  • A new approach has been proposed for the incremental analysis of the nonsteady state large deformation of planar anisotropic elastic-plastic sheet forming. A mathematical brief review of a constitutive law for the incremental deformation theory has been presented from flow theory using the minimum plastic work path for elastic-plastic material. Since the material embedded coordinate system(Lagrangian quantity) is used in the proposed theory the stress integration procedure is completely objective. A new return mapping algorithm has been also developed from the general midpoint rule so as to achieve numerically large strain increment by successive control of yield function residuals. Some numerical tests for the return mapping algorithm were performed using Barlat's six component anisotropic stress potential. Performance of the proposed algorithm was shown to be good and stable for a large strain increment, For planar anisotropic sheet forming updating algorithm of planar anisotropic axes has been newly proposed. In order to show the effectiveness and validity of the present formulation earing simulation for a cylindrical cup drawing and front fender stamping analysis are performed. From the results it has been shown that the present formulation can provide a good basis for analysis for analysis of elastic-plastic sheet metal forming processes.

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Deformation Behaviors of Materials during Nanoindentation Test and Simulation by Three-Dimensional Finite Element Analysis (재료의 나노인덴테이션 변형 거동과 3차원 유한요소해석)

  • Kim Ji-soo;Yang Hyeon-yun;Yun Jon-do;Cho Sang-bong
    • Korean Journal of Materials Research
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    • v.14 no.6
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    • pp.436-442
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    • 2004
  • Elastic and plastic deformation behaviors of the high purity aluminum and the silica glass were studied using nanoindentation and finite element analysis(FEA) techniques. Berkovich- and cone-type indenters were used for the nanoindentation test. Deformation behaviors and nanoindent profiles of elastic, elastic-plastic or plastic materials were clearly visualized by FEA simulation. Effects of the penetration depth and strain hardening on the deformation behavior were examined. Pile-up and sink-in behaviors were studied by using FEA technique. Degree of pile-up or sink-in was found to be a function of the ratio of elastic modulus to yield strength of materials. FEA was found to be an effective method to study deformation behaviors of materials under nanoindentation, especially in the case when pile-up or sink-in phenomena occurred.

Influence of Chucking Forces upon the Accuracy of Circular Hole in Boring Process on the Turning (선반으로 보링가공 할 때 척킹력이 가공 정도에 미치는 영향)

  • Lee, Sang-Soo;Kang, Shin-Gil;Jeon, Young-Seog
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.17 no.2
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    • pp.58-64
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    • 2008
  • The cutting process of materials is accompanied with the elastic and plastic deformation due to chucking forces in the boring process of thin holes on the turning. Upon removal of chucking forces at the end of process, the original shape is remained in the plastic deformation; on the other hand, it is modified in the elastic deformation due to spring back. Fixing materials by chucks on the turning has influence on roundness because the process is conducted with unbalanced distribution load induced from the fixing of three jaws. Moreover, the amount of spring back depends on the magnitude of fixing forces. We studied the change of roundness according to fixing forces as well as the method to reduce the influence of chucking forces.

Realistic Cloth Simulation using Plastic Deformation (소성변형특성을 이용한 사실적인 직물 시뮬레이션)

  • Oh Dong-Hoon;Jung Moon-Ryul;Song Chang-Geun;Lee Jong-Wan
    • Journal of KIISE:Computing Practices and Letters
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    • v.12 no.3
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    • pp.208-217
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    • 2006
  • This paper presents a cloth simulation technique that implements plastic deformation. Plasticity is the property that material does not restore completely to the original state once deformed, in contrast to elasticity. We model cloth using a particle model, and posit two kinds of connections between particles, i.e. the sequential connections between immediate neighbors, and the interlaced connections between every other neighbors. The sequential connections represent the compression and tension of cloth, and the interlaced connections the bending in cloth. The sequential connections are modeled by elastic springs, and the interlaced connections by elastic or plastic spring depending on the amount of the current deformation of the connections. Our model is obtained by adding plastic springs to the existing elastic particle model of cloth. Using the new model, we have been able to simulate bending wrinkles, permanently deformed wrinkles, and small wrinkles widely distributed over cloth. When constructing elastic and plastic spring models for sequential and interlaced connections, we took pain to prevent the stiffness matrix of the whole cloth system from being indefinite, in order to help achieve physical stability of the cloth motion equation and to improve the effectiveness of the numerical method.