Eigen theory of elastic mechanics for anisotropic solids

1　ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅｔｒａｄｉｔｉｏｎａｌｔｈｅｏｒｙｏｆｅｌａｓｔｉｃｍｅｃｈａｎｉｃｓｉｓｃｏｍｐｏｓｅｄｏｆｔｈｒｅｅｆｕｎｄａｍｅｎｔａｌｅｑｕａｔｉｏｎｓ,ｗｈｉｃｈｉｓｅ ｑｕｉｌｉｂｒｉｕｍｅｑｕａｔｉｏｎ ,ｈａｒｍｏｎｙｅｑｕａｔｉｏｎ ,ａｎｄｇｅｎｅｒａｌ ｉｚｅｄＨｏｏｋｅ’ｓｌａｗ .Ｔｈｅｆｏｒｍｅｒｔｗｏｅｑｕａｔｉｏｎｓｈｏｌｄｆｏｒａｌｌｓｏｌｉｄｍａｔｅｒｉａｌｓｕｎｄｅｒｔｈｅｃｏｎｄｉｔｉｏｎｏｆｃｏｎｔｉｎｕｉｔｙ ,ｂｕｔｔｈｅｌａｔｔｅｒｉｓｒｅｌ…     

Operationalized principle of elastic mechanics

1　ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅｄｉｖｉｄｉｎｇｐｈｅｎｏｍｅｎｏｎｏｆｍｏｔｉｏｎ ,ｗｈｉｃｈｉｓｄｅｓｃｒｉｂｅｄｉｎｑｕａｎｔｕｍｍｅｃｈａｎｉｃｓ ,ｉｓｔｈｅｇｅｎｅｒａｌｌａｗｉｎｍａｔｅｒｉａｌｗｏｒｌｄ .Ｉｔｅｘｉｓｔｓｎｏｔｏｎｌｙｉｎｍｉｃｒｏｍｅｃｈａ ｎｉｓｍ ,ｂｕｔａｌｓｏｉｎｃｏｎｔｉｎｕｕｍ .Ｆｏｒｅｘａｍｐｌｅ ,ｗｈｅｎｓｔｕｄｙｉｎｇｔｈｅｍｅｃｈａｎｉｃａｌｖｉｂｒａｔｉｏｎａｎｄｔｈｅｅｌａｓｔｉｃｗａｖｅｏｆｓｏｌｉｄ ,ｗｈｅｎｓｔｕｄｙｉｎｇｔｈｅｍｏｔｉ…     

高精度随动数控凸轮轴磨床砂轮架模态分析

利用SolidWorks软件建立了JKM8330高精度随动数控凸轮轴磨床砂轮架的三维模型,导入ABAQUS有限元分析软件,采用弹簧阻尼单元模拟轴承弹性支承的方法,建立了砂轮架的动力学分析有限元模型。通过分析计算,获得了砂轮架的前9阶振型和模态频率,并深入研究了不同轴承弹性支承刚度对砂轮架模态频率的影响规律。结果表明:可以通过调整轴承弹性支承刚度较好地控制砂轮架的模态频率,进而可以减小砂轮架的振动,从而保证机床磨削加工精度及可靠性。研究结果为高精度随动数控凸轮轴磨床的结构优化设计提供了参考。     

平整机机架有限元分析

轧机机架载荷条件和结构形式比较复杂,借助大型有限元分析软件ANSYS,利用有限元分析的手段,对平整机进行了弹性力学结构分析,得出了在平整过程中其模态频率、变形情况与载荷分布等详细、直观的分析结果,并通过材料力学与结构力学的计算进行对比,对两种方法进行互相弥补。     

具有弹性连接的组合机身压力机振动分析

针对组合机身压力机的结构特点 ,采用自由界面模态综合法进行振动分析 ,为使计算模型符合由拉紧螺栓实现各组合部件间弹性连接的实际结构 ,形成了弹性连接刚度阵 ,并对相关结构的刚度阵进行了修正 ,用该模型对一新型双击式螺旋压力机进行了计算 ,计算得到的固有频率与实测值相符。     

EIGEN THEORY OF ELASTIC DYNAMICS FOR ANISOTROPIC SOLIDS

１ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅｃｏｎｃｅｐｔｏｆｅｉｇｅｎｅｌａｓｔｉｃｉｔｙｏｒｉｇｉｎａｔｅｄｆｒｏｍＫｅｌｖｉｎ’ｓｗｏｒｋ［１，２］．Ｉｔｉｓｉｎｌａｓｔｄｅｃａｄｅｔｈａｔｅｉｇｅｎｅｌａｓｔｉｃｉｔｙｗａｓｓｔｕｄｉｅｄａｇａｉｎａｎｄ...     

结构裂纹对弹性梁振动特性的影响

研究了裂纹扩展引起的结构柔度变化以及裂纹界面接触对弹性梁振动特性的影响。基于断裂力学和能量原理推导了含横向裂纹弹性梁的局部柔度模型,分析了常见形式裂纹均匀梁的局部柔度,给出了相应的无量纲柔度系数计算公式;结合梁的弯曲振动方程,探讨了含裂纹悬臂梁的振动特性。算例表明：裂纹形式对弹性梁的柔度影响明显,裂纹界面接触会引发参数振动,界面滑动摩擦阻尼对稳定梁的振动响应具有重要作用。     

板料弹塑性弯曲应力应变中性层位置关系探讨

通过对板料弹塑性弯曲应力应变分析 ,利用材料力学中的平面曲杆理论 ,提出了板料大曲率弹塑性弯曲塑性应力应变中性层和弹性应力应变中性层均向内移动并重合的观点     

Damage mapping with a degrading elastic modulus using piezospectroscopic coatings

The development of piezospectroscopic (PS) composites has enabled the creation of a non-destructive evaluation (NDE) technique which integrates piezospectroscopy, digital image correlation (DIC) and analytical multi-scale mechanics to map the elastic modulus of a coated material. The measured elastic modulus was represented as a normal distribution with a mean value (32.2 GPa) which is within 8% of the conventionally recorded modulus (35 GPa). Damage mechanics are applied to map elastic degradation in situ mechanical loading with an average uncertainty (~10 GPa) that was sufficient in observing subsurface, progressive damage patterns which are unique to the coated material.     

异种材料连接中的界面力学问题

界面力学是异种材料连接界面强韧性设计的理论基础.主要介绍与异种材料连接接头界面力学有关的界面边缘应力奇异性和断裂控制参量等基本概念与分析方法.     

ZLK15装载机动臂横梁的计算方法研究

装载机由于工作过程循环往复,负载情况经常发生变化,因而其工作装置中各构件常常发生破坏,其中破坏最严重的是横梁.本文首先通过横梁的连接特点和受力条件建立了横梁的力学模型,然后从横梁的几何尺寸、材料强度、使用频率、应力水平等方面进行了详细研究,得出该构件可以用线弹性断裂理论进行力学计算和分析,并根据材料厚度与断裂韧度的关系得出横梁的计算属于平面应力问题的结论.     

Damage analysis and cracking model of reinforced concrete structures with rebar corrosion

The damage of concrete cover in reinforced concrete structures induced by reinforcing steel corrosion is investigated in this study. The damage process of the concrete cover can be divided into two distinct stages: the non-cracking stage and the partial cracking stage. An analytical model based on damage mechanics and elastic mechanics is developed to predict the concrete cracking due to steel corrosion. Based on this model, the expansive pressure and the radial loss of steel bar are discussed. Parametric studies are carried out to examine the effects of the correlative factors on the expansive pressure and the steel loss.     

基于“应变重构”的热轧带钢C翘缺陷调控研究

由残余应力不平衡所导致的C翘缺陷是热轧带钢生产过程中难以回避的板形问题,但实际生产中缺乏有效的调控手段。采用基于弹性断裂力学原理的裂纹柔度法,研究了平整加工过程残余应力的演变规律,提出了基于加工过程金属流动性特征的“应变重构”方法,高效、便捷地改善了热轧带钢的平直度缺陷及应力问题。应用上述原理,分析了热轧生产中普遍存在的C翘缺陷的改善机制,并给出了现场应用案例。     

石油套管气密接头密封过盈量的分析与计算

以弹性力学对圆管过盈配合应力、应变关系做了分析,最终找到确定石油套管气密接头(特殊扣)密封过盈量的计算方法。     

轴承和结合面动力学对刀尖频响函数的影响分析

基于Timoshenko梁理论、传递矩阵法和动柔度耦合子结构分析技术(RCSA),提出了一种刀尖频响函数预测方法。由于避免了多段Timoshenko梁的模态分析和模态叠加带来的累积误差,该方法较模态叠加法具有更高的计算精度和效率。重点分析了主轴-刀柄和刀柄-刀具结合面参数以及单个轴承动力学对刀尖频响函数的影响。研究结果表明:轴承动力学主要控制主轴-刀柄-刀具系统的刚体模态,主轴-刀柄结合面参数主要影响系统的第一阶弹性模态,刀柄-刀具结合面参数主要影响系统的第二阶弹性模态。研究结果为结合面参数辨识研究提供了理论基础和技术手段。     

Fatigue mechanics of WC–Co cemented carbides

The fracture and fatigue behavior of a fine-grained WC–10 wt% Co hardmetal is investigated. Mechanical characterization included flexural strength and fracture toughness as well as fatigue limit and fatigue crack growth (FCG) behavior under monotonic and cyclic loads, respectively. Considering that fatigue lifetime of cemented carbides is given by subcritical crack growth of preexisting defects, a linear elastic fracture mechanics (LEFM) approach is attempted to assess fatigue life–FCG relationships for these materials. Following the experimental finding of an extremely high dependence of FCG rates on the applied stress intensity for the hardmetal studied, the LEFM analysis is concentrated, from a practical design viewpoint, on addressing the fatigue limit–FCG threshold correlation under infinite fatigue life conditions. Thus, fatigue limit associated with natural flaws is estimated from FCG threshold experimentally determined for large cracks under the assumptions that (1) similitude on the FCG behavior of small and large cracks applies for cemented carbides, and (2) critical flaws are the same, in terms of nature, geometry and size, under monotonic and cyclic loading. The reliability of this fatigue mechanics approach is sustained through the excellent agreement observed between estimated and experimentally determined values for the fatigue limit under the different load ratios investigated.     

Role of microtexture in the interaction and coalescence of hydrogen-induced cracks

The role of microtexture in hydrogen-induced crack interaction and coalescence is investigated in line pipe steels using electron backscatter diffraction. Experimental evidence shows that, depending on the local grain orientation, crack interaction and coalescence can depart from the conditions predicted by the mixed-mode fracture mechanics of isotropic linear elastic materials. Stress simulation and microtexture analysis are used to explain the experimental observations.     

Springback in stringer sheet stretch forming

Stringer sheets are sheet metal structures stiffened by bifurcations in the cross-section. In order to create spatially curved light-weight structures they may serve as preforms for sheet metal hydroforming. The stiffness of sheets altered by stringers is expected to affect the hydroforming results. In particular influences of the geometric inhomogeneity on the extent and orientation of springback are of interest. They are investigated by means of mathematical analysis and forming experiments. A modal analysis of formed stringer sheets is conducted in order to understand the different impacts of stringers on the elastic behaviour of parts and springback after forming.     

基于弹性应变能密度的结构损伤与断裂判据

本文针对材料变形损伤与断裂过程进行了文献资料的综述,并在此基础上,总结出了由弹性应变能密度表征的结构损伤与断裂判据。该判据综合应用了连续损伤力学、细观损伤力学和断裂力学的方法,从材料力学性能参数和构件几何要素出发,对结构件的变形损伤和断裂行为进行了数学描述。