• Title/Summary/Keyword: deformation behaviors

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Characterization of Superplastic Deformation Behaviors of 7075 Al Alloy (초소성 7075알루미늄 합금의 변형특성 평가)

  • 권용남;장영원
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 1998.03a
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    • pp.65-71
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    • 1998
  • The superplastic deformation behaviors of 7075Al alloy have been characterized experimentally and analyzed by the internal variable theory of inelastic deformation. A simple rheological model including the grain boundary sliding has been used to interpret the superplastic deformation behaviors. A series of load relaxation and tensile tests have been carried out for 7075Al alloy at the various temperatures. The superplastic deformation of 7075Al alloy is confirmed to consist of the grain boundary sliding and accommodating grain matrix defprmation.

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Characteristics of Strength and Deformation of Aluminum Honeycomb Sandwich Composites Under Bending Loading (굽힘 하중을 받는 알루미늄 하니컴 샌드위치 복합재료의 강도 및 변형 특성)

  • Kim Hyoung-Gu;Choi Nak-Sam
    • Proceedings of the Korean Society For Composite Materials Conference
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    • 2004.10a
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    • pp.61-64
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    • 2004
  • The strength characteristics as well as deformation behaviors of honeycomb sandwich composite (HSC) structures were investigated under bending in consideration of various failure modes such as skin layer yielding, interface-delamination, core shear deformation and local buckling. Deformation behaviors of honeycomb sandwich plates were observed with various types of aluminum honeycomb core and skin layer. Their finite-element analysis simulation with a real model of honeycomb core was performed to analyze stresses and deformation behaviors of honeycomb sandwich plates. Its results were very comparable to the experimental ones. Consequently, the increase in skin layer thickness and in cell size of honeycomb core had dominant effects on the strength and deformation behaviors of honeycomb sandwich composites.

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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.

A Practical App개ach of Stress Path Method for Rational Settlement Estimation of Saturated Clay Deposit : Part I (Evaluation and Use of Characteristic Deformation Behaviors) (포화 점성토지반 침하량의 합리적 평가를 위한 실용적인 응력경로법 적용방법 : Part I (특성변형거동의 평가와 활용))

  • Kim Chang-Youb;Chung Choong-Ki
    • Journal of the Korean Geotechnical Society
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    • v.21 no.4
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    • pp.83-98
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    • 2005
  • In this paper, a conceptual approach of the stress path method was newly proposed for a rational estimation of settlements of saturated clay deposits. In the proposed approach, settlement-related characteristic deformation behaviors of a specific clay deposit, which can cover all probable stress changes expected in the field, are experimentally evaluated in advance. Then settlements of various structures constructed on the deposit are easily estimated with only the characteristic deformation behaviors and without any additional experimental effort. In Part I of this paper, in order to provide practicality to the new conceptual approach, we developed a detailed procedure which is capable of evaluating characteristic deformation behaviors of a saturated clay deposit with only a limited number of tests and easily predicting deformations under a given stress change using the characteristic deformation behaviors. The applicability of the developed procedure was clearly shown by presenting an actual application example.

Deformation Behaviors of Polymeric Materials by Taylor Impact (Taylor 충격시험에 의한 폴리머재료의 변형거동)

  • Park, Sung-Taek;Shin, Hyung-Seop;Park, Jung-Soo;Choi, Joon-Hong;Kim, Jeong-Tae
    • Proceedings of the KSME Conference
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    • 2007.05a
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    • pp.232-237
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    • 2007
  • The deformation of polymers under high loading-rate conditions will be a governing factor to be considered in their impact-resistant applications such as protective shields and transparent armor. In this paper, the deformation and fracture behaviors of polymeric materials such as PE, PC and PEEK have been investigated by Taylor Impact tests. Taylor cylinder impact tests and high speed photography are introduced to examine the deformation behavior under dynamic loading condition. 20 mm air gun was used to perform the impact experiments. Cylindrical projectiles have been impacted onto a hardened steel anvil at a velocity ranging from 100 to $350\;ms^{-1}.$ Along the barrel line, a photo-sensor which measures the speed of the projectile, four digital cameras which has shutter speed of 1/917,000sec and a rigid anvil were set up. After impact experiments, the shapes of projectiles and images taken using high speed cameras were analysed. Depending on materials adopted, they showed a variety in deformation and fracture behaviors.

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Deformation and Fracture Behavioos of Soda-lime Glass by Sliding Microindentation (미끄럼 미소압입에 의한 소다석회 유리의 변형 및 파괴 거동)

  • 안유민;최상현;박상신
    • Tribology and Lubricants
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    • v.13 no.4
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    • pp.18-25
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    • 1997
  • The various deformation and fracture behaviors under light loads in soda-lime glass under sliding Vickers indentation have been studied. In soda-lime glass, deformation and fracture behaviors can be classified into four different patterns by applied load. At very light load (<0.1N), plastic deformation only occurred. At low loads (0.1~0.8N), median crack, appear. At intermediate loads (0.8~3.0N), median and lateral cracking occurred leading to a large chipping. At high loads (3.0~6.0N), a crushed zone was observed with median crack. The friction experiment finds that the increasing in the friction coefficients coincides with the onset of crushing in soda-lime glass.

A Study on the Nano-Deformation Behaviors of Single Crystal Silicon and Amorphous Borosilicate Considering the Mechanochemical Reaction (기계화학적 반응을 고려한 단결정 실리콘과 비정질 보로실리케이트의 나노 변형 거동에 관한 연구)

  • 윤성원;신용래;강충길
    • Transactions of Materials Processing
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    • v.12 no.7
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    • pp.623-630
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    • 2003
  • Nanomachining process, static nanoplowing, is one of the most promising lithographic technologies in terms of the low cost of operation and variety of workable materials. In nanomachining process, chemical effects are more dominant factor compared with those by physical deformation or fracture. For example, during the nanoscratch on a silicon surface in the atmosphere, micro protuberances are formed due to the mechanochemical reaction between diamond tip and the surfaces. On the contrary, in case of chemically stable materials, such as ceramic or glass, surface protuberances are not formed. The purpose of this study is to understand effects of the mechanochemical reaction between tip and surfaces on deformation behaviors of hard-brittle materials. Nanometerscale elasoplastic deformation behavior of single crystal silicon (100) was characterized with micro protuberance phenomena, and compared with that of borosilicate (Pyrex glass 7740). In addition, effects of the silicon protuberances on nanoscratch test results were discussed.

Recrystallization Behaviors of Ordered and Disordered Structures in Ll2 Type Ni3Fe Alloy (Ll2형 Ni3Fe 합금에서 규칙격자와 불규칙격자의 재결정거동)

  • Choi, C.S.;Kang, S.H.
    • Journal of the Korean Society for Heat Treatment
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    • v.4 no.2
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    • pp.47-53
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    • 1991
  • Recrystallization behaviors of ordered and disordered structures in $Ll_2$ type $Ni_3Fe$ alloy were studied through hardness measurement and differential thermal analysis. When the disordered structure was isothermally aged at $480^{\circ}C$ below order-disorder transition temperature, the hardness of the structure was increased due to progressive ordering with increasing aging time. The hardness of the disordered structure was increased rapidly with increasing deformation degree up to 10%, and then gradually increased with further deformation degree. while the hardness of the ordered structure was increased rapidly with increasing deformation degree up to 10%, showing a constant hardness value up to 50% and gradually decreased with further deformation degree. The hardness of the ordered structure was higher than that of the disordered structure at all same deformation degrees. The recrystallization temperature of the ordered and disordered structures were decreased with increasing deformation degree. At the same deformation degrees, the recrystallization temperature of the ordered structure was lower than that of the desordered structure.

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The Effect of Plastic Strain on the Superplastic Deformation Behavior (초소성변형특성에 미치는 소성변형랴의 영향)

  • 권용남;장영원
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 1997.03a
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    • pp.291-293
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    • 1997
  • The effect of strain accumulation on the superplastic deformation behavior has been investigated through a series of load relaxation tests. The experimental results were analyzed using the recently proposed inelastic constitutive theory. The superplastic deformation of fine grained materials is confirmed to consist of grain boundary sliding and accommodating grain matrix deformation. However the flow behavior is changed with the plastic strain. It is believed that the microstructural changes such as grain growth and cavitation affect the superplastic deformation behaviors.

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A Study on the Deformation Behaviors around Twin Tunnels Using Scaled Model Tests (쌍굴터널 주변지반의 변형거동에 관한 모형실험 연구)

  • 김종우;박지용
    • Tunnel and Underground Space
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    • v.14 no.5
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    • pp.381-390
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    • 2004
  • In this study, scaled model tests were performed to investigate the deformation behaviors around twin tunnels. Eleven types of test models which had respectively different pillar widths, rock types and loading conditions were mode, where the modelling materials were the mixture of sand, plaster and water. The models with shallower pillar width were cracked under lower pressure than the models with thicker pillar width, and they showed the more tunnel convergences and the clear spatting failures. The models of hard rock were cracked under 50% higher pressure than the models of soft rock and they showed the less tunnel convergences. The failure and deformation behaviors of twin tunnels were also dependent on the loading conditions of models. Futhermore, the results of FLAC analysis were qualitatively coincident with the test results.