• 제목/요약/키워드: Radial stress

검색결과 418건 처리시간 0.026초

두꺼운 복합재 원통의 잔류응력 측정방법 (Measurement Method of Residual Stresses in Thick Composite Cylinders)

  • 김종운;박동창;이대길
    • 한국복합재료학회:학술대회논문집
    • /
    • 한국복합재료학회 2005년도 춘계학술발표대회 논문집
    • /
    • pp.245-248
    • /
    • 2005
  • During manufacturing thick composite cylinders, large thermal residual stresses are developed and induce catastrophic interlaminar failures. Since the residual stresses are dependent on many process parameters, such as temperature distribution during cure, cure shrinkage, winding tension, and migration of fibers, calculation of the residual stresses is very difficult. Therefore a radial-cut method have been used to measure the residual stresses in the composite cylinders. But the conventional radial-cut method needs to know numerous material properties which are not only troublesome to obtain but also vary with change of fiber arrangement during consolidation. In this paper, a new radial-cut method with cut-cylinder-bending test was proposed and the measured residual stresses were compared with calculated thermal residual stresses. It was found that the new radial-cut method which does not need to know any of material properties gave better estimation of residual stresses regardless of radial variation of material properties. Additionally, interlaminar tensile strength could be obtained by the cut-cylinder-bending test.

  • PDF

Flexural Vibration of Clamped and Simplv Supported Sectorial Plates with Combinations of Simply Supported and Free Radial Edges

  • Han, Bong-Ko;Kim, Joo-Woo
    • Nuclear Engineering and Technology
    • /
    • 제31권2호
    • /
    • pp.214-225
    • /
    • 1999
  • An accurate method is presented for flexural vibrations of sectorial plates having simply supported-free and free-free radial edges, when the circular edge is either clamped or simply supported. The classical Ritz method is employed with two sets of admissible functions assumed for the transverse vibratory displacements. These sets consist of : (1) mathematically complete algebraic-trigonometric polynomials which gurantee convergence to exact frequencies as sufficient terms are retained, and (2) comer functions which account for the bending moment singularities at re-entrant comer of the radial edges having arbitrary edge conditions. Accurate (at least four significant figures) frequencies and normalized contours of the transverse vibratory displacement are presented for the spectra of corner angles [90$^{\circ}$, 180$^{\circ}$(semi-circular), 270$^{\circ}$, 300$^{\circ}$, 330$^{\circ}$, 350$^{\circ}$, 355$^{\circ}$, 360$^{\circ}$ (complete circular)] causing a re-entrant comer of the radial edges. Future solutions drawn from alternative numerical procedures and finite element techniques may be compared with these accurate results.

  • PDF

Influence of a weak superposed centripetal flow in a rotor-stator system for several pre-swirl ratios

  • Nour, Fadi Abdel;Rinaldi, Andrea;Debuchy, Roger;Bois, Gerard
    • International Journal of Fluid Machinery and Systems
    • /
    • 제5권2호
    • /
    • pp.49-59
    • /
    • 2012
  • The present study is devoted to the influence of a superposed radial inflow in a rotor-stator cavity with a peripheral opening. The flow regime is turbulent, the two boundary layers being separated by a core region. An original theoretical solution is obtained for the core region, explaining the reason why a weak radial inflow has no major influence near the periphery of the cavity but strongly affects the flow behavior near the axis. The validity of the theory is tested with the help of a new set of experimental data including the radial and tangential mean velocity components, as well as three components of the Reynolds stress tensor measured by hot-wire anemometry. The theoretical results are also in good agreement with numerical results obtained with the Fluent code and experimental data from the literature.

Magneto-thermo-elastic response of exponentially graded piezoelectric hollow spheres

  • Allam, M.N.M.;Tantawy, R.;Zenkour, A.M.
    • Advances in Computational Design
    • /
    • 제3권3호
    • /
    • pp.303-318
    • /
    • 2018
  • This article presents a semi-analytical solution for an exponentially graded piezoelectric hollow sphere. The sphere interacts with electric displacement, elastic deformations, electric potentials, magneto-thermo-elasticity, and hygrothermal influences. The hollow sphere may be standing under both mechanical and electric potentials. Electro-magneto-elastic behavior of magnetic field vector can be described in the hollow sphere. All material, thermal and magnetic properties of hollow sphere are supposed to be graded in radial direction. A semi-analytical technique is improved to deduce all fields in which different boundary conditions for radial stress and electric potential are presented. Numerical examples for radial displacement, radial and hoop stresses, and electric potential are investigated. The influence of many parameters is studied. It is seen that the gradation of all material, thermal and magnetic properties has particular effectiveness in many applications of modern technology.

Solution for a semi-infinite plate with radial crack and radial crack emanating from circular hole under bi-axial loading by body force method

  • Manjunath, B.S.;Ramakrishna, D.S.
    • Interaction and multiscale mechanics
    • /
    • 제2권2호
    • /
    • pp.177-187
    • /
    • 2009
  • Machine or structural members subjected to fatigue loading will have a crack initiated during early part of their life. Therefore analysis of members with cracks and other discontinuities is very important. Finite element method has enjoyed widespread use in engineering, but it is not convenient for crack problems as the region very close to crack tip is to be discretized with very fine mesh. However, as the body force method (BFM), requires only the boundary of the discontinuity (crack or hole) to be discretized it is easy versatile technique to analyze such problems. In the present work fundamental solution for concentrated load x + iy acting in the semi-infinite plate at an arbitrary point $z_0=x_0+iy_0$ is considered. These fundamental solutions are in complex form ${\phi}(z)$ and ${\psi}(z)$ (England 1971). These potentials are known as Melan potentials (Ramakrishna 1994). A crack in the semi-infinite plate as shown in Fig. 1 is considered. This crack is divided into number of divisions. By applying pair of body forces on a division, the resultant forces on the remaining 'N'divisions are to be found for which ${\phi}_1(z)$ and ${\psi}_1(z)$ are derived. Body force method is applied to calculate stress intensity factor for crack in semi-infinite plate. Also for the case of crack emanating from circular hole in semi-infinite plate radial stress, hoop stress and shear stress are calculated around the hole and crack. Convergent results are obtained by body force method. These results are compared with FEM results.

STS 304 TIG 용접시 발생하는 열응력 해석에 관한 연구 (A Study on the Analysis of the Thermal Stress in Process of STS 304 TIG Welding)

  • 고준빈;최원두;이영호
    • Journal of Welding and Joining
    • /
    • 제19권6호
    • /
    • pp.658-663
    • /
    • 2001
  • Residual stress caused in the weldments with high restraint force are often during welding observed in the weldments of large size nozzles or radial tanks. The reason is that quantitative analysis about thermal stresses during welding is lack for this weldments. To verify FEM theory, the temperature was measured with thermocouple in a real time in this paper. Also analysis of the thermal stress for welding condition is performed by ABAQUS program package on various welding condition in STS butt welding.

  • PDF

Stress and Electric Potential Fields in Piezoelectric Smart Spheres

  • Ghorbanpour, A.;Golabi, S.;Saadatfar, M.
    • Journal of Mechanical Science and Technology
    • /
    • 제20권11호
    • /
    • pp.1920-1933
    • /
    • 2006
  • Piezoelectric materials produce an electric field by deformation, and deform when subjected to an electric field. The coupling nature of piezoelectric materials has acquired wide applications in electric-mechanical and electric devices, including electric-mechanical actuators, sensors and structures. In this paper, a hollow sphere composed of a radially polarized spherically anisotropic piezoelectric material, e.g., PZT_5 or (Pb) (CoW) $TiO_3$ under internal or external uniform pressure and a constant potential difference between its inner and outer surfaces or combination of these loadings has been studied. Electrodes attached to the inner and outer surfaces of the sphere induce the potential difference. The governing equilibrium equations in radially polarized form are shown to reduce to a coupled system of second-order ordinary differential equations for the radial displacement and electric potential field. These differential equations are solved analytically for seven different sets of boundary conditions. The stress and the electric potential distributions in the sphere are discussed in detail for two piezoceramics, namely PZT _5 and (Pb) (CoW) $TiO_3$. It is shown that the hoop stresses in hollow sphere composed of these materials can be made virtually uniform across the thickness of the sphere by applying an appropriate set of boundary conditions.

입자결합모델을 이용한 횡방향 변형률 제어 하에서의 암석의 일축 및 삼축압축시험의 수치적 모사 (Numerical Simulation of Radial Strain Controlled Uniaxial and Triaxial Compression Test of Rock Using Bonded Particle Model)

  • 이창수;권상기;전석원
    • 터널과지하공간
    • /
    • 제21권3호
    • /
    • pp.216-224
    • /
    • 2011
  • 본 연구에서는 Class II 거동에 대해 입자결합모델을 이용하여 수치해석적인 방법으로 살펴보았으며, 횡방향 변형률 제어 압축시험을 수치해석적으로 모사할 수 있는 방법을 제시하였다. 수치해석에서 사용된 미시변수는 스웨덴 Aspo Hard Rock Laboratory에서 수행한 일축압축시험을 이용하여 결정하였다. 제시된 수치해석 기법을 이용해 Aspo 암석의 Class II 거동을 효과적으로 모사할 수 있었으며, 수치해석의 결과는 실험실 시험 결과와 잘 일치하였다.

Investigation of Radial Distributions of Tangential Strains and of Moisture Contents within a Log Cross Section by Circumferential Slices

  • Choi, Jun-Ho;Lee, Nam-Ho
    • Journal of the Korean Wood Science and Technology
    • /
    • 제36권2호
    • /
    • pp.20-28
    • /
    • 2008
  • This study was carried out to provide the so-called circumferential slicing method for investigating radial distributions of the tangential strains and of moisture contents within the log cross section (LC) of Kalopanax pictus during indoor drying it. While the heartwood showed an almost uniform moisture content distribution in the range of about 50~55% in case of the green wood, it has gradually decreased toward the outer side, showing about 19% of moisture content difference from the innermost slice. Although the moisture gradient along the radial direction has gradually become gentle as drying progresses, the sapwood of the outer side represented the moisture contents below the fiber saturation point after 24 hours of drying while the heartwood in the inner part showed the moisture contents higher than the fiber saturation point. The pith side was laid under the tensile stress after 24 hours of drying, and then gradually decreasing toward the bark side, and showed the distribution being switched again to the tensile stress on the bark side. As the drying has progressed, this trend got more intensified, and finally showed the U-shaped distribution model after 48 hours of drying. The circumferential slice test is considered to be suitable in quantitatively determining the tangential strains and moisture content within a LC.

전면접착형 록볼트의 보강효과에 관한 연구 (A Study on the Reinforcement Effects of Fully-Grouted Rock Bolts)

  • 정해성;문현구
    • 터널과지하공간
    • /
    • 제9권3호
    • /
    • pp.194-203
    • /
    • 1999
  • 본 연구에서는 록볼트의 역학적 거동을 파악하기 위하여 지하공동에 설치된 단일 록볼트에 발생하는 축응력 분포, 록볼트-그라우트 접촉면에서의 전단응력 분포와 중립점의 위치를 분석하였으며, 현장의 다양한 지질조건에 대한 록볼트의 보강효과를 분석하기 위하여 여러가지 지반조건과터널크기에서 록볼트의 설치간격과설치길이를 변화시키며 전산해석을 수행하였다. 전산해석결과, 최대 인장응력 및 전단응력의 분포를 파악할 수 있었으며, 중립점의 위치에 영향을 주는 인자가 공동의 굴착폭임을 알 수 있었다. 또한 패턴볼팅으로 보강된 원형공동에서 록볼트에 의한 암반의 봉압효과는 응력 증가비를 사용하여 분석하였으며, 소성대 감소효과와지반 변위 감소효과는 각각 소성대 감소비와 변위 감소비를 사용하여 분석하여 록볼트의 보강효과 경향을 파악할 수 있었다. 이러한 보강효과의 경향분석 결과는 실제 터널의 안정적 설계에 적용할 수 있을 것으로 판단된다.

  • PDF