共查询到20条相似文献,搜索用时 140 毫秒
1.
2.
3.
4.
针对卷取机关键零件在设计时繁冗复杂的力学校核工作,以ANSYS分析软件的APDL语言为基础,VB为开发工具设计了力学分析程序,实现了ANSYS三维模型的自动建立、网格的自动划分、约束与载荷的自动加载以及力学分析结果的输出,大大提高了该类产品的设计校核效率。 相似文献
5.
6.
奥氏体钢四点弯曲疲劳行为的数值模拟与试验 总被引:1,自引:0,他引:1
采用有限元方法对奥氏体钢四点弯曲疲劳试验的加载过程进行了数值模拟,分析了疲劳试样的应力分布与疲劳寿命,确定了受力分布相对均匀的试样的合理尺寸范围,并对一种Cr-Mn奥氏体钢进行了四点弯曲疲劳试验研究,对比分析了有限元模拟与试验结果间的差别与原因。结果表明,试样尺寸不同,两加载辊之间的应力分布规律不同;当t/h(材料厚度/加载辊距)1.4时,最大应力出现在靠近加载辊的内侧,距加载辊0.4~0.5 mm;当t/h=1.2~1.4时,两加载辊之间的应力分布比较均匀,最大模拟应力与加载应力(理论值)的误差小于5%;当t/h1.2时,最大应力出现在两加载辊中间,其中t/h=0.7~0.8时,模拟值最大应力与加载应力比较接近,但应力分布均匀性较低;采用t/h≈1.3的试样进行疲劳试验研究,试验后的疲劳裂纹均产生在两加载辊中间,在加载辊外侧未发现疲劳裂纹,这与模拟结果相一致;模拟疲劳极限为498 MPa,循环4.0×10~6周次,试验测定疲劳极限为505MPa,循环3.6×106周次,模拟值略小于试验值,可见有限元方法可以较准确地预测材料的疲劳寿命。 相似文献
7.
8.
9.
建设中的宝钢COREX 3000在技术上的主要改进 总被引:1,自引:0,他引:1
对宝钢COREX3000在技术上的主要改进重点进行了阐述,并介绍了为提升COREX3000技术的竞争力所开展研发工作概要。COREX3000的设计充分吸取了C1000、C2000生产中的经验教训及高炉的成功经验,在炉体、耐材、炉体冷却系统以及布料装置等方面作了大量改进,设计产能由C2000的80万t扩大到了150万t。结合罗泾工程本身特点,宝钢正在COREX煤气、粉矿、粉煤有效利用等方面展开技术研发,以实现整个工艺流程的优化,力求COREX3000在技术经济指标、作业率、炉役寿命等方面比C2000有较大的提高。 相似文献
10.
球磨机的研磨元件是设备中的核心部件,类似于水平放置的单向推力球形轴承,磨球在上磨环和下磨环之间自由滚动,球磨机的研磨元件所需要的研磨压力来自于液压弹簧加载装置.为了对原液压弹簧加载装置进行优化,设计了一种基于原有液压系统的新型弹簧加载装置. 相似文献
11.
Muhammad Abid Abdul Waheed Awan David H. Nash 《Canadian Metallurgical Quarterly》2010,136(12):1519-1527
Performance of a bolted flange joint is characterized mainly due to its “strength” and “sealing capability.” A number of analytical and experimental studies have been conducted to study these characteristics only under internal pressure loading. A very limited amount of work is found in the literature under combined internal pressure and bending loading. Due to the ignorance of this external loading, i.e., bending loading, the optimized performance of the bolted flange joint cannot be achieved. The present design codes do not address the effects of bending loading on the structural integrity and sealing ability. To investigate joint strength and sealing capability under combined loading, an extensive comparative experimental and numerical study of a nongasketed flange joint is carried out and overall joint performance and behavior is discussed. Actual joint load capacity is determined under both the design and proof test pressure with maximum additional external bending loading that can be applied for safe joint performance. In addition, as experimentally it is impossible to test different flange joint sizes under combined loading application, hence finite element model developed and verified with the experimental results, presented in this paper can be used as base to study the behavior for different nongasketed flange joint sizes for different classes under combined pressure and bending loading. 相似文献
12.
13.
14.
Laboratory Testing Material Property and FE Modeling Structural Response of PAM-Modified Concrete Overlay on Bridges 总被引:1,自引:0,他引:1
Portland cement concrete overlay on bridge deck is subjected to distresses of cracking and interface debonding under the effects of repeated vehicle loading and temperature cycling. In order to improve the overlay performance, this research used the polyacrylamide (PAM) polymer to modify the mechanical properties of concrete. The direct shear and impact resistance tests were designed to measure the interface bonding strength and dynamic performance, respectively. The comprehensive and flexural strength and three-point bending fatigue tests were conducted following the standards. Meanwhile, the three-dimensional finite-element (FE) models of the T-girder and box-girder bridges under the moving traffic loadings were built to analyze the stress response and improve the structural design. An analytical model of flexural stress was developed and validated the FE modeling results. A rubber cushion was designed in the FE model to “absorb” the flexural stress. Laboratory testing results indicate that PAM can significantly improve the flexural strength, bonding strength, impact resistance, and fatigue life of concrete. The modified concrete with 8% PAM by mass of cement poses higher flexural strength and impact resistance than concretes with other PAM percentages. FE simulation results indicate that there exists a critical overlay thickness inducing the maximum interface shear stress, which should be avoided in the structural design. The rubber cushion can effectively relieve the flexural stress. 相似文献
15.
介绍了一种聚乙内酯(PCL)微/纳米纤维在弯曲实验中弹性性能的尺度效应模型。该模型是基于非局部理论的一种考虑非局部效应的微尺度模型,通过该模型可以计算出纤维材料的弹性性能在弯曲变形中的两种尺度效应:一种跟纤维的直径相关(D-SD),另外一种跟纤维的长度相关(L-SD)。采用原子力显微镜对PCL微/纳米纤维进行测试,对比PCL微/纳米纤维的三点弯曲实验数据与理论模型的计算结果,说明该模型可以解释纤维弹性性能的尺度效应,并且也适用于其他高分子纤维材料的微尺度弹性力学性能分析。 相似文献
16.
Bruce W. Christ 《Metallurgical and Materials Transactions B》1973,4(8):1961-1965
Some bending usually occurs in uniaxial testing systems due to small unavoidable misalignment. The resulting elastic strain
gradient can lead to significant differences between axial strain and extreme surface bending strains, especially at small
strains. A three-point microstrain measurement around a cylindrical sample permits evaluation of the extreme strains and of
the precision of alignment. A three-point, parallel-plate capacitance strain gage having a linear output with displacement
was designed to evaluate bending of tensile samples in the microstrain range. The resolution of the gage was 3 parts in 10,000
at plate separations of 0.010 in. Varying misalignment resulted in extreme elastic bending strains at the sample surface of
the order of tens to hundreds of micro-in. per in. larger than the axial strain. Analysis of the mechanics of bending in uniaxial
loading demonstrated that: 1) the average applied stress divided by the average elastic strain always gives a unique number,
Young's modulus, and 2) the average microplastic strain is not uniquely related to the average applied stress, but rather
depends upon precision of alignment. The influence of bending on the determination of the average stress at which microplastic
flow initiates is discussed, and a method for making meaningful comparisons of plastic microstrain data generated with significant
misalignment is suggested. 相似文献
17.
Segmental bridges with unbonded prestressed tendons have some advantages over conventional concrete bridges, such as weather-independent construction and the corrosion protection of the prestressing tendons. This paper analyzes the behavior of a prestressed segmental bridge with unbonded tendons under combined loading of torsion, bending, and shear. According to experimental research, a modified skew bending model was developed to calculate the load-carrying capacity of segmental bridges subjected to combined bending, shear, and torsion. A finite element method (FEM) was used to investigate the deflection behavior of such a structure and to check the theoretical model. The theoretical and FEM research results compared favorably with test results. Finally, suggestions for the design and construction of segmental bridges with external prestressing were made. 相似文献
18.
针对某钢厂100t转炉→LF钢包精炼炉→板坯连铸机工艺流程和生产试验数据,探讨了板坯连铸一种内外弧型中间裂纹的发生机制。结果表明,连铸坯鼓肚收缩应变是中间裂纹产生的外因,钢的化学成分决定其高温力学性能,是中间裂纹产生的内因。某钢厂连铸板坯中间裂纹的产生是连铸坯鼓肚收缩应变和钢种的高温力学性能共同作用的结果,而弯曲矫直应变是中间裂纹扩展的重要影响因素,可能导致中间裂纹的扩展。结合钢种和铸坯规格的合理辊缝设计对控制中间裂纹至关重要。 相似文献
19.
TL J?rvinen P Kannus H Siev?nen P Jolma A Heinonen M J?rvinen 《Canadian Metallurgical Quarterly》1998,13(9):1475-1482
Physical loading creating high peak strains on the skeleton at high strain rates is suggested to be the most effective type of activity in terms of bone mineral acquisition. This study assessed the effects of sudden impact loading on mineral and mechanical bone properties in 13-week-old Sprague-Dawley rats. The rats were randomly assigned as sedentary controls (SED, n = 10), control animals receiving low-intensity exercise (EX, n = 15), and experimental animals receiving low-intensity exercise combined with sudden impact-loading (EX + IMP, n = 15). In the EX group, the rats walked in a walking mill at a speed of 10 cm/s for 20 minutes/day, 5 days/week for 9 weeks. In the EX + IMP group, the program was identical to the EX group except for the additional sudden impacts administered to their skeleton during the walking exercise. At the start, there were 50 impacts per session, after which their number was gradually increased to 200 impacts per session by week 6 and then kept constant until the end of the experiment, week 9. These horizontally and vertically directed body impacts were produced by a custom-made walking mill equipped with computer-controlled high-pressure air cylinders. After sacrifice, both femora of each rat were removed and their dimensions, bone mineral content (BMC) by dual-energy X-ray absorptiometry, and mechanical properties by femoral shaft three-point bending and femoral neck compression were determined. The cortical wall thickness increased significantly in the EX and EX + IMP groups as compared with SEDs (+7.6%, p = 0.049 and +10%, p = 0.020, respectively). The EX + IMP group showed +9.0% (p = 0.046) higher cross-sectional moment of inertia values than the EX group. No significant intergroup differences were seen in the BMC values, while the breaking load of the femoral shaft (EX + IMP vs. SED +8.8%,p = 0.047) and femoral neck (EX + IMP vs. SED +14.1%, p = 0.013) was significantly enhanced by the impact loading. In conclusion, this study indicates that mechanical loading can substantially improve the mechanical characteristics of a rat femur without simultaneous gain in its mineral mass. If this is true in humans too, our finding gives an interesting perspective to the numerous longitudinal exercise studies (of women) in which the exercise-induced gains in bone mass and density have remained mild to moderate only. 相似文献
20.
《钢铁研究学报(英文版)》2016,(3):225-230
Micro-deformation behavior and mechanical properties of columnar-grained Fe-6.5 mass%Si alloy before and after warm rolling were investigated by means of micro-indentation and three-point bending tests.The results show that the columnar-grained Fe-6.5mass%Si alloy before warm rolling presents sink-in mode of micro-indentation,while pile-up mode with a number of arc-shaped deformation bands exists in the warm-rolled alloy.Compared with that of the alloy before warm rolling,the maximum bending fracture stress and maximum bending fracture deflection of the warm-rolled alloy are increased by 96% and 50%,respectively.The different micro-deformation behavior and mechanical properties of the columnar-grained Fe-6.5mass%Si alloy are ascribed to the changes of dislocation density,dislocation configuration and long-range order degree,which significantly improve the room temperature plasticity of the alloy after warm rolling. 相似文献