Papers by Keyword: Thermoelasticity

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Authors: R. Marsili, Michele Moretti, J. Pirisinu, Gian Luca Rossi
Abstract: Motorcycle frames are mechanical components that need to be optimised in terms of performance and costs but with a limited amount of resources compared to, for example, car frames. Fatigue testing of the component is required for qualification and this is typically performed by using rotating drums with steps or servo-controlled hydraulic actuator based test benches. Therefore a fast and simple measurement and testing technique that operates during the fatigue tests will be a very useful tool. In this paper the possibility of analysing these components by measuring the stress levels and stress concentration in critical parts by thermoelasticity is investigated. The development of a multibody model, useful to simulate the typical working conditions of the motorcycle frame, is also described.
Authors: Rwei Ching Chang, Jhy Jen Shyr
Authors: A. R. Khorshidvand, M. Javadi
Abstract: In this paper, a new solution is presented for one-dimensional steady-state mechanical and thermal stresses in a FG rotating hollow disk and cylinder. The material properties for FG are expressed as nonlinear exponential functions through the radius and Poisson’s ratio is taken to be constant. The temperature distribution is derived from first law of thermodynamics by solving energy equation, with a general thermal and mechanical boundary conditions on the inside and outside surfaces. Heat conduction and Navier equations are solved analytically by choosing elliptic cylinder coordinates system and the results are shown for displacement and stress components along the radial direction.
Authors: Jiang Wu, Zhi Hua Zhao, Ge Xue Ren
Abstract: Thermal load is non-ignorable in the design and analysis of high precision and reliable space deployable structures. A new approach based on flexible multibody system is presented in order to investigate the thermoelastic effect on the deployment of space structure. Dynamic equations of an Euler Bernoulli beam element with transient thermal load are derived in Absolute Nodal Coordinate Formulation. The temperature distribution in the beam section is assumed as linear, which is reasonable for slender beams. The resulting generalized thermoelastic forces can be decomposed into thermal axial force and thermal bending moments, which can cause tension/compression and bending of the beam respectively. The dynamic equations of the beam element are then assembled into a flexible multibody system. Deployment analysis of a space mechanism with transient thermal load is studied with the new approach. Simulation result shows that thermoelasticity could cause static deformation of the final configuration as well as affect the external driving forces.
Authors: Akira Shimamoto, Hiroshi Ohkawara, Hong Yang Zhao
Abstract: Stress intensity factor K is analyzed by measuring distribution of sum of the principal stresses around slit tip by an infrared stress measuring device. Under the biaxial tensile stress, both K-values of the isotropic materials with slit angle 0° and 45° show there is no influence of the slit angle at Mode I. The tolerance of the measured K-values of the test specimens which are compared with measured K-values by photoelastic method are around 10-20and these increase as applied cyclic load increases. These tolerance can be reduced up to about 8% by modifying measurements. The effectiveness of the thermoelastic stress measurement method to KI value analyzing under biaxial tensile stress was confirmed.
Authors: David Backman, R.J. Greene
Abstract: The efficacy of thermoelastic stress analysis for use in the study of moderately curved gas turbine blades is considered over a frequency range of 68 Hz to 3.4 kHz. A selection of blades, both industrial examples and simplified planar laboratory specimens, are excited at their natural vibration frequencies using both electromagnetic shakers and piezoelectric stack actuators, in order to develop a cyclic displacement of the blade surface and hence a cyclic variation in surface stress condition. Results are shown using both snapshot array and rolling array infrared detector systems, and the data then used to generate maps of normalized principal surface stress sum, and hence the mode shapes of vibration, including the first four excitation modes.
Authors: Dong Won Kim, Nak Kyu Lee, Kyoung Hoan Na, Dong Il Kwon
Authors: G. Brustenga, R. Marsili, Michele Moretti, J. Pirisinu, Gian Luca Rossi
Abstract: In this paper a new measurement technique to perform thermoelastic stress analysis on rotating mechanical component is proposed. The idea is to use a particular realization of the Dove prism optical system, optimized to work width infrared radiation, able to give a fixed output image of a rotating surface on where a normal thermoelastic measurement system can be applied. The realization of a first prototype of this optical system is described. First results on a test case are illustrated.
Authors: Leszek B. Magalas
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