共查询到17条相似文献,搜索用时 15 毫秒
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For critical load bearing structures, it is often necessary to experimentally determine the load distribution on the structure
so that accurate finite element models can be developed for stress and fatigue life predictions. An inverse problem approach
is presented here for computing or calibrating the loads and boundary conditions acting on a structure. This enables the creation
of more accurate finite element models, especially for structures that have complicated load distribution and compliant boundary
conditions. The method presented here involves minimizing the least square error between the strains computed using the finite
element model and the strains and displacements obtained experimentally. The nodal loads and the compliance at fixed boundaries
are treated as the variables in the optimization problem. The compliance is modeled as springs attached at the nodes that
are on the boundary where the structure is restrained. The method is verified by computing the loads and boundary conditions
when displacements, maximum shear strain or both are available at large number of points on the surface of the structure.
The experimental data set was generated using the luminescent photoelastic coating (LPC) technique. 相似文献
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Experimental Techniques - 相似文献
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P. M. Talaia A. Ramos I. Abe M. W. Schiller P. Lopes R. N. Nogueira J. L. Pinto R. Claramunt J. A. Simões 《Experimental Mechanics》2007,47(3):355-363
This paper presents an experimental methodology to determine plated and intact femur strains using fiber Bragg gratings and
strain gauges. A plated and an intact synthetic femur were used and loaded under a simplistic static load of 600 N. A stainless
steel (316L) plate was used to fixate a simulated 45° fracture on one femur. Strains were recoded at the same sites on both
femurs. Strain shielding is shown to be more pronounced at the distal region of the plated femur. The experimental methodology
based on fiber Bragg grating sensors is a novel approach to assess bone plate strains, which could also be used to obtain
biologic tissue and implant surface strains in locations where conventional strain gauge use is not technically feasible. 相似文献
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The elastic strains induced in the constituent wires of parallel wire strands under tensile loading were measured using neutron
diffraction. The elastic strains carried by the individual wires depended very strongly on the boundary conditions at the
grips and on radial clamping forces. The friction forces between the wires were quite significant and should not be neglected
in analytical or numerical formulations of strain partitioning in parallel wire cables. 相似文献
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基于三维数字图像相关方法(3D-DIC)的拉伸实验研究了铸铁的拉伸力学性能,分别得到了应力-应变曲线、弹性模量、抗拉强度、延伸率等拉伸力学性能参数.将3D-DIC应力-应变的测试结果与目前实验中使用广泛的接触式引伸计方法的实验结果作了对比,得到两者的应力-应变曲线基本重合,弹性模量相差不超过4%.此外,还对3D-DIC和机械引伸计的应变绝对误差和相对误差作了详细比较,实验表明3D-DIC在铸铁拉伸力学性能测试中具有足够的应变测量精度,完全可以取代传统引伸计成为一种有效的非接触式变形测量手段. 相似文献
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润滑油在轴承内的分布及其变化规律对轴承的润滑性能有显著影响. 在本文中搭建了滚动轴承模拟试验台,基于激光诱导荧光方法实现了滚动轴承内钢球-外圈接触区附近润滑油分布的观察与测量,获得了润滑油供给油层分布的三维形貌图,研究了不同供油量和转速对轴承内部供给油层分布的影响规律. 试验结果表明充分润滑条件下相邻钢球-外圈接触区供给油池之间会形成相互连接的油带;在高速情况下,钢球-外圈接触区供给油层厚度受前一个接触区尾部空穴影响而减小;供油量的增加会增大表观油池,但并不意味着入口有效供油层的增加. 相似文献
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Laboratory tests have been carried out in order to investigate the influence of small changes in load direction on the performance of a steadily loaded hydrodynamic crown journal bearing. Hydrodynamic pressures, temperature distribution on the bush internal surface, shaft temperature, oil flow rate and bush torque were measured for fixed sets of operating conditions, at three different groove locations () with respect to the line of load ( = 0, –30, and +30 degrees). For each groove location quantitative information is provided concerning to the influence of applied load and shaft rotational speed on the performance characteristics. Changing the location of the groove around the load line did affect flow rate, bush torque and maximum hydrodynamic pressure, but only had a slight effect on bush maximum temperature. 相似文献
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An innovative technique for measuring both the shape, the displacement, the strain and the temperature fields at the surface
of an object using a single stereovision sensor is proposed. The sensor is based on two off-the-shelf low-cost high-resolution
uncooled CCD cameras. To allow both dimensional and thermal measurements, the sensor operates in the visible and near infrared
(NIR) spectral band (0.7–1.1 μm), and a radiometric and geometric calibration of the sensor is required. This technique leads
to a low-cost camera-based simplified instrumentation that gives simultaneously dimensional/kinematical and thermal field
measurements. 相似文献
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A. M. Korsunsky J. Liu M. Golshan D. Dini S. Y. Zhang W. J. Vorster 《Experimental Mechanics》2006,46(4):519-529
Residual elastic strains in a bent bar of titanium alloy Ti-6Al-4V were measured using high energy diffraction on station 16.3 at SRS Daresbury. Using a single bounce Laue crystal monochromator, diffraction peaks were collected for reflections (00.2), (10.1), (10.2) and (11.0) from the hcp alpha phase of the titanium alloy. Reference values of the lattice spacing for each of the reflections were found from the diffraction pattern collected from a stress-free sampling volume. The residual elastic strain values calculated on the basis of each reflection were then computed and plotted as a function of position across the bent bar. The average macroscopic residual elastic strain was computed using an averaging procedure taking into account the multiplicity of each reflection. Energy dispersive white beam diffraction from the same bent bar was used to collect diffraction patterns over the range of lattice spacings between 0.8 and 2.2 Å. Detector calibration was carried out using the procedure described in Liu et al. (2005) and detailed interpretation of the energy dispersive profiles was carried out allowing the identification of average residual elastic strains in the two principal phases present in the titanium alloy considered, the α-Ti hcp and the β-Ti bcc phases. Peak-specific residual strain profiles computed on the basis of monochromatic measurements show significant differences reflecting the variation in the elastic and plastic properties with grain orientation, i.e., crystal anisotropy. Using the contrast between the elastic and plastic properties of different directions within the α-Ti hcp lattice, the difference between residual elastic strains measured for (00.2) and (11.0) reflections was plotted, as well as the ‘difference strain’ between (00.2) and (10.1) reflections. These profiles show a good qualitative correlation with the plastic strain profile introduced by inelastic bending that was computed from the analysis of Pawley refinement of the energy-dispersive diffraction measurements. 相似文献
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Takuya Kawata Yoshitsugu Naka Koji Fukagata Shinnosuke Obi 《Flow, Turbulence and Combustion》2011,86(3-4):419-437
We have developed a probe-system for simultaneous measurement of three velocity components and pressure in turbulent flows. A miniature total pressure probe is placed adjacent to the sensors of a triple hot-film probe in order to achieve the spatial resolution which is equivalent to that of the triple hot-film probe itself. The instantaneous static pressure is calculated from measured velocity and total pressure by means of a newly developed processing method based on the Bernoulli equation for unsteady flows. The measurements were undertaken in a turbulent wing-tip vortex flow. The look-up table method is employed for the calibration of the hot-film probe so accurate velocity data could be obtained over a wide range of the flow-attack angles. It is also demonstrated that the present probe-system is capable of measuring fluctuations in both velocity and pressure in the 20?C650 Hz frequency range. The distribution of the fluctuating pressure obtained by this indirect method is in good agreement with the results from direct measurements of static pressure, demonstrating the promising performance of the present method. Furthermore, an improvement in the ability to make measurements of the velocity?Cpressure correlation across the wing-tip vortex is achieved. This improvement is possible because the effects of lateral velocity components are properly taken into account in the present formulation. The investigation regarding the transport equation budget for turbulent kinetic energy shows an anomalous structure of turbulence in this flow, mainly due to the meandering of the vortex, and the measurement of pressure diffusion is found to play an important role in the characterization of this kind of flow. 相似文献