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排序方式: 共有314条查询结果,搜索用时 15 毫秒
1.
考虑动力稳定装置的轮轨非线性接触、轮轨间的间隙传动、夹钳油缸和水平油缸的等效刚度建立了动力稳定装置动态特性键合图模型.使用分段函数表达式实现了轮轨间的间隙传动.针对不同夹持力对于能量的传递效率与作业效果进行了深入分析与探究,确定了所需最小的水平油缸的推力. 相似文献
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Microstructures, Reaction Kinetics and Properties of Reaction Between Magnesium and Silica Glass 下载免费PDF全文
In earlier calculation models,the stiffness centers in frame-shear wall structures have been located by the structural torsion stiffness.However,the results are illogical owing to the difference between the distortion character and the shears distribute mechanism of the frames and shear walls.In this paper,a new formula for calculating story stiffness is introduced,which can consider the stiffness of the frames and shear walls at the same time.The structural stiffness centers,the torsion eccentric distances and torsion effect are calculated,and the stiffness of elements is considered also.It is shown that the concept of the presented stiffness model is clear and the results are reasonable,which can be used to calculate the appreciative torsion effect. 相似文献
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OBJECTIVE: To determine failure strength, stiffness, and failure mode of 4 suture materials in equine linea alba. STUDY DESIGN: Randomized complete block design. SAMPLE POPULATION: Linea albas collected from 12 adult horses (mean weight, 475 kg; mean age, 10 years). METHODS: The ventral abdominal fascia, including the linea alba, was collected and bisected along the linea alba into right and left halves. Each half was divided into four, 5-cm sections extending from the umbilicus cranially, and randomly assigned to 1 of 4 suture materials: 2 polydioxanone (2 PD), 3 polyglactin 910 (3 PG), 6 polyglactin 910 (6 PG), and 7 polydioxanone (7 PD). A single cycle to failure test was performed on each specimen at a distraction rate of 100 mm/min. Differences in failure strength and stiffness for the materials were evaluated using a mixed linear model with significance set at P<.05. RESULTS: In 94 of 96 test sections, constructs failed by suture failure. There were significant differences in failure strength (P<.0001) and stiffness (P<.001) among the suture/tissue constructs. 7 PD had the highest breaking strength (316.8 N) followed by 6 PG (281.3 N), 3 PG (229.9 N), and 2 PD (193.0 N). Six PG had the largest stiffness (14 N/mm) followed by 3 PG (12.7 N/mm), 7 PD (10.1 N/mm), and 2 PD (7.2 N/mm). Suture breaking strength and stiffness were not affected by linea or fascia thickness, individual horse, half of the linea alba, or abdominal wall position. Eighty-five (90.4%) suture loops failed adjacent the knot. CONCLUSIONS: When tested in single cycle to failure, suture material was more likely to fail than the linea alba. Larger suture materials had higher breaking strengths than smaller suture materials and stiffness was also affected by suture material and size. CLINICAL RELEVANCE: Given its high initial breaking strength and its relatively longer in vivo strength retention, 7 PD seems an appropriate choice of suture material for closure of the equine linea alba when maximal short-term failure strength is desired. 相似文献
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Garcia-Seco E Wilson DA Cook JL Kuroki K Kreeger JM Keegan KG 《Veterinary surgery : VS》2005,34(6):571-578
OBJECTIVE: To determine normal cartilage stiffness values in different weight-bearing and non-weight-bearing areas of 3 different equine joints, and to evaluate the relationship between cartilage stiffness and glycosaminoglycan (GAG) and collagen content. STUDY DESIGN: Compressive stiffness of the articular cartilage was measured in 8 horse cadaver femoropatellar (FP), tarsocrural (TC), and metatarsophalangeal (MT) joints. Gross evaluation, collagen content, GAG content, and histologic appearance were assessed for each measurement location. ANIMALS: Eight equine cadavers (4 intact females, 4 castrated males; 7 Quarter Horse or Quarter Horse type, 1 Arabian; aged 4-12 years, weighing 400-550 kg). METHODS: The articular surfaces of 8 equine cadaver FP, TC, and MT joints were grossly evaluated for signs of articular cartilage pathology. Stiffness at preselected sites (FP joint-6 sites; TC joint-3 sites; MT joint-4 sites) was determined using an arthroscopic indentation instrument. Biochemical composition (collagen, GAG content) and histologic evaluation (modified Mankin score) were assessed for each measurement site. RESULTS: All cartilage from all sites evaluated was determined to be normal based on macroscopic and histologic assessments. No significant correlation between Mankin scores and cartilage stiffness values was observed. Site differences in cartilage stiffness were measured in all 3 joints (P<.001). GAG or collagen content had a significant positive correlation with stiffness values in 6 of 13 sites (P<.05, r>0.622, r2>0.387). CONCLUSION: Relative cartilage stiffness values measured in healthy equine joints are site dependent and can be measured using an indentation device intended for arthroscopic application. CLINICAL RELEVANCE: An indentation instrument provided an objective means of determining relative compressive stiffness of articular cartilage. Further research needs to be performed to confirm the site and joint differences observed in this study in clinically normal horses and to determine if the tester can be used clinically to predict articular cartilage pathology. 相似文献
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摩擦耗能支撑减震技术是一种行之有效的减震措施,本文利用ANSYS分析了斜撑刚度对结构减震效果的影响,得出对于本文算例斜撑刚度与结构刚度的比值为2-6时,减震效果最好。 相似文献
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考虑轮胎接地摩擦的非线性特性,建立了基于侧向变刚度的轮胎多边形磨损模型,并对系统的稳定性进行了分析,指出轮胎的自激振动是一种由系统Hopf分岔引起的稳定周期振动现象,通过数值仿真得到了引起胎面自激振动的车速和车轮前束角范围.结果表明:轮胎多边形磨损为一种典型的非线性自激振动现象,其发生与胎面的侧向振动有关,磨损边数近似等于胎面的侧向振动频率与车轮转动频率之比.所建模型能够很好地解释轮胎多边形磨损的形成机理. 相似文献