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Advanced Engineering Science

Gongcheng Kexue Yu Jishu/Advanced Engineering Science
Journal ID : AES-16-10-2021-25
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Abstract :

Volumetric error (VE) is determined by machine tool geometric error elements (GEE). Most of VE models in recent studies have a common issue that some GEE are missing in models explicit mathematical expressions, which directly affects machine tool VE prediction accuracy. Therefore, a methodology for complete modeling machine tool VE was proposed. Multi-body system theorem and homogeneous coordinate transformations were borrowed as analysis approaches. On the basis that initial positions and original errors eigen matrix were fully considered, VE model was guaranteed to have total machine tool GEE. Furthermore, aiming at the residual error limitation in traditional NC code VE compensation technique, NC code coordinates optimization design problem was described to replace the former reversal accumulation process. Genetic algorithm (GA) was then utilized to solve the proposed optimization problem so that VE compensation residual error was eliminated. A horizontal machining center was selected as study object, on which both numerical and experimental analyses were performed to verify the proposed modeling methodology and compensation technique. The results indicated that complete VE model comprises total 21 GEE of machining center and that VE prediction was fairly accurate. It was also showed that NC code optimized compensation technique presented in this paper may promote machining center volumetric position precision (VPP). The maximum growth of VPP, compared to uncompensated value, was 90.92%. Research results can be regarded as theorem and engineering supports for investigations on numerical manufacturing equipment precision problems.

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Gongcheng Kexue Yu Jishu/Advanced Engineering Science
Journal ID : AES-16-10-2021-24
Total View : 1

Abstract :

To investigate the anti-seismic resilience of inter-story substructure of PEC column-steel beam frame with partial self-centering friction damped connection, a specimen with 1∶2 scale was designed and fabricated, then two tests before and after renovation were conducted under cyclic lateral loading. Based on the test observations and measurements, the specimens’ anti-seismic behaviors such as the hysteretic characteristics, lateral stiffness, self-centering function and energy-dissipation capacity were studied. The results indicated that rational dimension of bolt slotted hole was designed to achieve the force-transfer mechanism of partial self-centering friction damped connection at design-earthquake level and bearing-type connection was formed at maximum considered earthquake level; the force-transfer mode of concrete equivalent strut was formed in the panel zone due to pre-tension penetrating bolts and pre-tensioned bars, and reinforced gusset plate was designed to confine concrete in the panel zone, correspondingly the anti-seismic requirements of strong joint were met when the inter-story drift arrived at the inter-story drift limit of frame structure at design-based earthquake level, self-centering functions were sound for residual drifts of inter-story were 0.11% and 0.13%, respectively, while the inter-story drift surpassed the inter-story drift limit of frame structure at maximum considered earthquake level, self-centering functions were still good for residual drifts of inter-story were 0.42% and 0.44%, respectively; with simple repairmen, the force-transfer developing process, lateral stiffness, self-centering function and evolution mechanism of energy dissipation were restored, hence the specimen owned superior anti-seismic resilience.

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