Papers by Keyword: Bi-Axial

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Authors: Julia Repper, Markus Niffenegger, Steven van Petegem, Werner Wagner, Helena van Swygenhoven
Abstract: Complex strain paths are often applied to materials during production processes. This paper shows the first successful in-situ biaxial mechanical tests during neutron diffraction performed on a cruciform steel sample and reports on the differences compared to uniaxial deformation. Digital image correlation is demonstrated to be an appropriate tool to monitor spatially resolved the macroscopic straining. The new, modular biaxial machine that will be installed at the neutron diffractometer POLDI is presented.
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Authors: Martin Petrenec, Veronique Aubin, Jaroslav Polák, Suzanne Degallaix
Abstract: Austenitic-ferritic duplex stainless steel has been subjected to uniaxial and biaxial nonproportional cyclic loading with the same equivalent strain amplitude. The dislocation structures in specimens fatigued to fracture using both types of loadings were studied and compared. Uniaxial cyclic loading, both in austenitic and in ferritic grains, produces simple structures due to activation of predominantly one slip system. Non-proportional cyclic loading results in formation of cell and wall structures and thus in higher stress response of the material.
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Authors: X.H. Meng, W.W. Wang, J.H. Zhou, Yu Pu Song
Abstract: A model of attenuation of residual strength with number of cycles has been founded .In this model the constant confined stress and maximum stress of fatigue loading are both considered. 55 specimens of plain concrete are tested under biaxial compressive fatigue loading with constant confined stress. Based on the data of experiment, the coefficients of the model are determined. The residual strength attenuating curves are shown in the paper. The model can be used to predict the residual life of specimen under biaxial compressive loading with constant confined stress. The results of prediction show that the suggested method is better than the Miner rule.
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Authors: Lu Cui, Peng Wang
Abstract: Lifetime prediction of steam turbine components under biaxial thermo-mechanical fatigue (TMF) loading of modern high chromium steel is prerequisite for design optimization. In this paper a phenomenological method which envelopes the synthesis of stress strain hysteresis loops and damage assessment under considering creep fatigue interaction is extended to multiaxial loadings. It is proposed as a post processing step depending on the results of a preceding finite element analysis based on a constitutive material model. Recalculation of biaxial service-type experiments on cruciform specimen of modern high chromium rotor steel 10CrMoWVNbN shows satisfactory results for lifetime estimation.
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Authors: Joshua E. McLeod, Scott D. Moss
Abstract: This paper reports on the multiphysics modelling of a bi-axial vibration energy harvesting (VEH) approach, with experimental validation of the model predictions. The authors have developed a harvester able to generate voltage under bi-axial vibrations. The harvesting approach is based on a magnetoelectric (ME) transducer that is positioned between a fixed magnet and oscillating ball bearing, which steers a changing magnetic field through the transducer to generate a voltage. The transducer combines magnetostrictive and piezoelectric properties to convert magnetic potential into electrical energy. Analytical modelling of this phenomenon is difficult due to the highly coupled nature of this interaction, so Comsol multiphysics software is used to make predictions of output using the finite element method (FEM). A peak open-circuit harvester voltage of 39.4 V is predicted for a ball bearing oscillating with 4.5 mm amplitude, agreeing reasonably well with measured harvester voltage of approximately 35 V. The modelling is applied to a two-dimensional representation of the system, which is shown to be sufficient for a basic understanding of the highly coupled nature of interactions, and a basis for optimising the magnetoelectric vibration energy harvesting approach.
465
Authors: Shou Hui Chen, Zheng Guo
Abstract: As a kind of flexible fabric reinforced composites, the woven membrane materials suffer from the bi-axial tensile loads in the application of the lightweight structures. Therefore, the experiments under bi-axial tensile loads are essential for the acquaintance of the mechanical characters of the membrane materials. This paper has summarized thoroughly the details of the bi-axial tensile tests, especially the in-plane cruciform tests. The aspects include the shape and configuration of the cruciform sample, the practice of the applied stresses and the testing of the strains in the two axial directions. It could be expected to be the reference for the establishment of the testing standard of the bi-axial tensile experiment for the membrane materials.
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Authors: Peter Tiernan, Alan Hannon
Abstract: One of the most restricting aspects of the biaxial tensile test for sheet metal is the design of the cruciform specimen. Although specimens of the cruciform type have previoussly been investigated quite extensively, no standard geometry for the cruciform specimen exists. Using a specifically designed pantograph apparatus for operation in a standard tensile testing machine, various cruciform specimens were analysed experimentally. Finite element modelling of the specimens was also conducted to establish optimum specimen geometry. Through a process of optimisation, a standard cruciform specimen was designed which can be used to accurately predict the mechanical behaviour of cold rolled low-carbon steel when formed in multiple directions simultaneously.
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Authors: Jun Hui Meng, Dong Xu Liu, Yi Zhang, Zhao Jia, Ming Yun Lv
Abstract: Tear propagation is a typical breakage modality of fabric laminates. In this paper, analysis methods and their empirical formulas about tear propagation of a kind of fabric laminate which is used in high altitude lighter-than-air vehicle (LTA) is studied. The methods include Griffith’s energy balance method, Thiele’s empirical formula method, Stress field consideration method and critical stress intensity factor method. Testing about tear propagation strength in biaxial stress is done by a tailor-made testing machine to study on the methods. And then a comparison is drawn between these formulas and results of the experimentation. Subsequently, advantages and disadvantages of these formulas and their scope of application are concluded. While by using the empirical formulas, the analysis of tear propagation of different incision shapes is given. It is useful for the further study on different fabric laminates.
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Authors: Bo Yang, Hui Zhao, Bo Dai
Abstract: A new biaxial decoupled resonant micro-accelerometer is researched. The new biaxial resonant micro-accelerometer consists of four same tuning forking resonators, four pair of decoupled beams, four lever mechanisms and a proof mass. The decoupling between two orthogonal axes is realized by the decoupling beams, which will benefit to isolate two axes acceleration detection. The simulation is implemented to verify the basic principle by the Ansys. The simulation results prove that the effective frequencies of two acceleration sensitive modes are 3.699 kHz and 3.718 kHz separately. Two pair of resonator modes which are 23.893 kHz, 23.946 kHz, 26.974 kHz and 26.999 kHz separately have about 3kHz difference in frequency in order to prevent the mutual interference. And the interference modes are isolated with effective mode apparently. The input-output characteristic simulation results indicate the y-axis scale factor is 57.1Hz/g and the coupling output in the x-axis is 0.0148Hz/g, while the x-axis scale factor is 56.1Hz/g and the coupling output in the y-axis is 0.0073Hz/g, which proves that the new biaxial resonant micro-accelerometer is practicable and has an excellent decoupled performance.
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Authors: M.D. Grah, Keith J. Bowman
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