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细长桁架臂卸载反弹动应力分布规律及试验
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作者 刘洋 付玲 +1 位作者 刘延斌 尹莉 《振动与冲击》 EI CSCD 北大核心 2024年第15期251-260,共10页
为研究细长桁架臂在卸载冲击下的动态响应变化规律,提出了基于等效梁振型函数的桁架臂动应力分布计算模型。根据等效梁振型函数,探讨了卸载后桁架臂动应力分布假设,分析了影响桁架臂卸载反弹动响应的相关参数。以装备细长桁架臂的动臂... 为研究细长桁架臂在卸载冲击下的动态响应变化规律,提出了基于等效梁振型函数的桁架臂动应力分布计算模型。根据等效梁振型函数,探讨了卸载后桁架臂动应力分布假设,分析了影响桁架臂卸载反弹动响应的相关参数。以装备细长桁架臂的动臂塔机为对象,建立了桁架臂精细化有限元模型和起重机刚柔耦合模型,通过仿真辨识了应力分布模型的关键参数。实施了动臂塔机系列载荷卸载冲击试验,桁架臂上主弦杆的动应力试验值与理论计算结果误差小于7%,表明动应力分布理论模型与实际相符。通过理论模型预测了极限工况下桁架臂上主弦杆动应力分布状态,发现在最大载荷卸载条件下起重臂动应力峰值超过结构承载极限,为卸载条件下起重机关键结构的优化设计提供依据。 展开更多
关键词 动应力分布模型 振型函数 桁架臂 刚柔耦合模型 卸载冲击试验
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Simulation of astronomical solar radiation over Yellow River Basin based on DEM 被引量:5
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作者 QIUXinfa ZENGYan +1 位作者 LIUChangming WUXianfeng 《Journal of Geographical Sciences》 SCIE CSCD 2004年第1期63-69,共7页
Based on the developed distributed model for calculating astronomical solar radiation (ASR), monthly ASR with a resolution of 1 km×1 km for the rugged terrains of Yellow River Basin was calculated, with DEM data ... Based on the developed distributed model for calculating astronomical solar radiation (ASR), monthly ASR with a resolution of 1 km×1 km for the rugged terrains of Yellow River Basin was calculated, with DEM data as the general characterization of terrain. This model gives an all-sided consideration on factors that influence the ASR. Results suggest that (1) Annual ASR has a progressive decrease trend from south to north; (2) the magnitude order of seasonal ASR is: summer>spring>autumn>winter; (3) topographical factors have robust effect on the spatial distribution of ASR, particularly in winter when a lower sun elevation angle exists; (4) the ASR of slopes with a sunny exposure is generally 2 or 3 times that of slopes with a shading exposure and the extreme difference of ASR for different terrains is over 10 times in January; (5) the spatial differences of ASR are relatively small in summer when a higher sun elevation angle exists and the extreme difference of ASR for different terrains is only 16% in July; and (6) the sequence of topographical influence strength is: winter>autumn>spring>summer. 展开更多
关键词 astronomical solar radiation (ASR) rugged terrains spatial distributions digital elevation model (DEM)
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