几何刚度矩阵的推导和应用   总被引：1，自引：0，他引：1  

张年文 《茂名学院学报》2004,14(3):45-48

以虚功原理为基础有限元进行梁柱的分析，应用很少，主要是于在计算中，荷载很小时，计算结果就不收敛了。因而也就很难应用于工程分析中。以虚功原理为基础推导得出了几何刚度矩阵，分析了计算不收敛的原因，得出结论：不考虑节点力因位移产生的不平衡力对几何刚度矩阵的影响，是计算结果不收敛的主要原因。算例说明了当考虑了这个影响以后，计算结果和文献给出的计算结果符合良好。  相似文献   

Equivalent Kelvin Impact Model for Seismic Pounding Analysis of Bridges     

DING Yang  YUE Fuqing  LI Zhongxian 《天津大学学报(英文版)》2006,12(Z1)

Based on Hertz contact theory, a method to determine the parameters of Kelvin impact model for seismic pounding analysis of bridges is proposed. The impact stiffness of Kelvin model is determined by the ratio of maximum impact force to maximum contact deformation, which is calculated based on Hertz contact theory with considering the vibration effect. The restitution coefficient which has great influence on the damping coefficient of Kelvin impact model is investigated by numerical analysis. Numerical results indicate that the impact stiffness of Kelvin impact model increases with the increment of the Hertz contact stiffness, approaching velocity or the length ratio of short to long girders. Vibration effect has remarkable influence on the impact stiffness and cannot be neglected. The restitution coefficient decreases when approaching velocity increases or the length ratio of short girder to long girder decreasing. The practical ranges of impact stiffness and restitution coefficient are obtained as 3×108-6×108 N/m and 0.6-0.95 respectively.  相似文献   

非协调轴对称杂交应力元单元刚度矩阵的准确建立     

田炯  田宗漱 《中国科学院研究生院学报》1994,(1)

给出新型三类用理性杂交模式、根据一种修正的Ｈｅｌｌｉｎｇｅｒ－Ｒｅｉｓｓｎｅｒ原理、建立高精度非协调轴对称实体旋转有限元时，其单元刚度矩阵的准确计算式。  相似文献   

泡沫混凝土刚度软化与剪力传递关系模型     

张静  刘向东 《科技通报》2015,(2):230-232

泡沫混凝土在应用中存在强度偏低、开裂、吸水等缺陷,在长期荷载作用下,泡沫混凝土会产生开裂,需要研究泡沫混凝土的刚度软化与剪力传递关系模型,准确描述混凝土结构长期变形及受力行为的徐变耦合特性,掌握服役期内的结构的长期变形及受力状态,为建筑结构防护提供参考。传统模型中仅考虑未开裂部分混凝土的徐变及开裂混凝土对整体刚度的影响,在裂缝的存在,使得混凝土结构刚度降低。提出一种基于裂缝坐标系下泡沫混凝土刚度软化与剪力传递关系模型,分析泡沫混凝土徐变产生及载重分配的机理,得到单轴受压条件下本构关系,按等效应力-应变关系来计算变化的切线弹性模量,在裂缝坐标系下,较准确地描述了泡沫混凝土的平均盈利比率变化与温度和刚度软化之间的关系,经算例验证表明,计算结果可靠,计算精度满足工程使用要求。  相似文献   

Relationship between Achilles tendon properties and foot strike patterns in long-distance runners     

Keitaro Kubo  Daisuke Miyazaki  Shigeharu Tanaka  Shozo Shimoju  Naoya Tsunoda 《Journal of sports sciences》2015,33(7):665-669

The purpose of this study was to investigate the relationship between Achilles tendon properties and foot strike patterns in long-distance runners. Forty-one highly trained male long-distance runners participated in this study. Elongation of the Achilles tendon and aponeurosis of the medial gastrocnemius muscle were measured using ultrasonography, while the participants performed ramp isometric plantar flexion up to the voluntary maximum. The relationship between the estimated muscle force and tendon elongation during the ascending phase was fit to a linear regression, the slope of which was defined as stiffness. In addition, the cross-sectional area of the Achilles tendon was measured using ultrasonography. Foot strike patterns (forefoot, midfoot and rearfoot) during running were determined at submaximal velocity (18 km · h^?1) on a treadmill. The number of each foot strike runner was 12 for the forefoot (29.3%), 12 for the midfoot (29.3%) and 17 for the rearfoot (41.5%). No significant differences were observed in the variables measured for the Achilles tendon among the three groups. These results suggested that the foot strike pattern during running did not affect the morphological or mechanical properties of the Achilles tendon in long-distance runners.  相似文献   

The impact of data reduction on the intra-trial reliability of a typical measure of lower limb musculoskeletal stiffness     

Mark P. Moresi  Elizabeth J. Bradshaw  David A. Greene  Geraldine A. Naughton 《Journal of sports sciences》2015,33(2):180-191

Double-leg repeated jumping tasks are commonly used as measures of lower limb stiffness in exercise science research. Within similar stiffness calculations, variation in data-reduction criteria exists. The impact of these varied data-reduction methods on stiffness measures is unknown. Sixteen adolescent female participants from varied physical activity backgrounds performed 15 self-paced, bent-knee continuous jumps (CJb) on two force plates. Leg stiffness was calculated as the ratio of the peak force and the centre of mass displacement for each contact. Using combinations of criteria based on previous literature, 83 data-reduction methods were applied to the raw data. Data reduction suitability was assessed based on intra-trial reliability, the number of participants excluded and the average contacts excluded. Four data-reduction methods were deemed suitable for use with adolescent female populations, with three consecutive contacts within 1 SD of the average jump frequency considered optimal. The average individual stiffness values were not greatly influenced by the data-reduction method; however, for a single participant, a stiffness change of up to 6 kN · m^?1 (30%) was observed. The role and potential impact of data-reduction methods used to evaluate measures of lower limb stiffness during repeated jumping tasks warrants consideration.  相似文献   

某轿车白车身静刚度试验台设计方案研究     

陆玉兵 《安徽职业技术学院学报》2021,(1):17-21

轿车行驶的可靠性和安全性很大程度上取决于车身刚度设计,针对某轿车白车身概念设计要求和车身静刚度相关理论,构建出静刚度检测系统,提出了车身刚度实时试验台设计方案。运用该试验台对白车身的静刚度进行检测,得到轿车或其核心部件在静态状态下的刚度变化规律,为真正意义上实现在车身刚度满足技术要求的条件下进行车身轻量化设计提供参考。  相似文献   

门式起重机刚度强度的有限元分析     

张大鹏  ;姚立影 《绵阳师范高等专科学校学报》2014,(8):1-7

门式起重机承受额定载荷时的结构刚度和结构强度是评估起重机最重要的两个指标.通过ANASYS对于某U型变频箱型双梁门式起重机进行计算.然后,依据《起重机设计规范GB3811-2008》对计算结果进行分析判定.计算结果表明：结构最大变形与最大局部应力不是发生在同一工况;结构的最大Von Mises应力及变形均在许用范围以内,结构静刚度、结构强度均能满足使用要求.ANSYS的计算结果为起重机的安全评估与检验检测提供了有益参考.  相似文献   

基于有限元分析模型建立的轿车车门动态特性分析     

赵建宁 《河北职业技术学院学报》2014,(1):39-42

轿车车门是轿车车身重要的组成部分,它的设计质量直接影响整车的安全性、造型效果、空气动力学特性、密封性及噪声等。轿车车门动态特性分析是基于车门有限元分析模型的建立,对轿车车门在自由状态下进行模态分析。文章在四种工况下对轿车车门的扭转刚度、下垂刚度进行分析。通过分析,为轿车车门结构设计选择及结构优化提供了理论依据。  相似文献   

道路刚度对浅埋暗挖法人行地道影响的有限元分析     

王哲  王哲  王志达 《科技通报》2012,28(9):97-102

修建人行地下通道是缓解城市交通拥挤、保障行人交通安全、提高城市运行效率的一项有效措施。人行地道施工不可避免对周边环境造成不利的影响,严重者可能影响地面建构筑物和地下管线的正常使用。本文通过对浅埋暗挖法修建杭州清泰街过街地道的有限元模拟,模拟CRD工法开挖方式通过考虑地道上方道路刚度与否两种模型的对比得出道路刚度对浅埋暗挖人行地道的地表沉降及地层变形的影响规律,并与实测数据进行了对比分析,得出较为一致的结果。研究对此类地道的施工与设计有一定的指导意义。  相似文献