共查询到18条相似文献,搜索用时 62 毫秒
1.
超声纯横波法测试45#钢的内部应力 总被引:1,自引:1,他引:1
声各向同性的金属材料在应力作用下,材料表现出声各向异性,这是用声弹性法分析材料内部应力的基础。本文用垂直于应力方向传播的超声纯横波对45#钢进行测试,测试时横波的偏振化方向分别平行和垂直于应力方向。实验结果表明:材料在拉、压应力作用下,相互正交的两超声纯横波的声速都发生了变化,且声各向异性因子与应力成线性关系。利用此关系可测试材料内部应力,提供了一种无损测试材料内部应力的方法,另外本实验方法也可以对材料内部残余应力进行评估。实验中利用回振法测量声速,可测量声速的微小变化,精度高。 相似文献
2.
3.
弹性体在表面冲击载荷下所激发的应力波 总被引:1,自引:0,他引:1
1 引言近年来,随着对工程中许多冲击破坏现象机理研究的不断深入,冲击载荷所激发的应力波传播问题越来越引起人们的关注.尽管,自Lamb 首先捉出并利用Fouricr 变换方法研究了弹性半空间在脉冲点源作用下激发应力波的传播问题之后,迄今已有许多学者,如 相似文献
4.
5.
6.
表面涂层材料的残余应力测量技术 总被引:2,自引:0,他引:2
本文采用电测盲孔法测定表面涂层材料残余应力的测量技术,在试件和表面涂层结构上进行测试.大量试验表明,此方法可靠、有效,可在工程实际中使用,为解决表面涂层“爆裂”等问题,提供了有效的测定残余应力的手段 相似文献
7.
本文对应力波载荷(加载速率KI≥105MPa m/s)作用下,动态断裂韧性测试技术中的非光学方法进行了较全面和较系统的研究,比较了各自的优缺点,并对不同方法的可靠性和适用范围进行了分析. 相似文献
8.
本文采用考虑裂纹面上具有任意分布载荷的线弹簧模型,在Kirchhoff板弯曲理论的假设下,将含半椭圆型表面裂纹的平板问题化为一组耦合的积分方程组进行求解,对均匀拉伸和纯弯曲两种载荷作用下的应力强度因子数值解,同经典线弹簧模型和有限元解进行了比较,并给出了经典线弹簧模型不能得到的、裂纹面上承受幂次不均匀应力分布时应力强度因子的数值解. 相似文献
9.
10.
有限元表面应力计算 总被引:1,自引:3,他引:1
用有限元[1]通用程序进行结构计算时,最常用的是位移法,因而计算得到的位移有较高的精度。由位移计算应力时,有限元法应用的是应力-应变关系和应变-位移关系,其中应变-位移是微商关系。在数值计算中,微商只能转化为差商等用插值近似处理。这样,虽然位移精度高,但应力的计算精度就被大打折扣。本文应用弹性力学辛体系理论[2],解析求解了位移和应力的影响函数。利用有限元程序计算得到的位移,由功互等定理,不需要微分插值,就可以得到指定点的应力,应力精度大大提高。工程实际中有许多问题的最大应力往往发生在构件表面。针对表面应力问题,本文给出了半平面表面应力的影响函数,进行了数值算例计算。计算结果表明,用本文提出的影响函数法求解一点的应力,其精度明显提高,并且计算结果有很好的稳定性。用本文的影响函数法编制成子程序,可作为有限元软件应力计算的一个模块,可以更好地发挥有限元程序的功效。 相似文献
11.
12.
13.
旋涡与行进表面水波相互作用的实验研究 总被引:1,自引:0,他引:1
采用振动板式造波器在二维水槽中生成近似单色的行进表面水波,采用夹板式涡发生器生成稳定上浮的涡对,在Froude数约为0.5的条件下,得到了水下涡对与不同波长和振幅的行进表面水波相互作用时的干扰图象,以实验方法验证了理论分析和数值计算的结果,并为进一步研究旋涡与行进表面水波的相互作用提供了一种实验研究方法 相似文献
14.
M. A. Kulesh V. P. Matveenko I. N. Shardakov 《Journal of Applied Mechanics and Technical Physics》2005,46(4):556-563
The problem of propagation of an acoustic surface Rayleigh wave in an infinite half-space is considered within the framework of the asymmetric theory of elasticity (Cosserat medium). It is assumed that material deformation is described not only by the displacement vector but also by an independent rotation vector. A global analytical solution of the problem in displacements is obtained. A comparative analysis of the solution obtained and the corresponding solution for the classical elastic medium is performed. Macroparameters characterizing the difference of the stress-strain state from that predicted by the classical theory of elasticity are introduced.__________Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 46, No. 4, pp. 116–124, July– August, 2005. 相似文献
15.
In this note a factorization technique based on the theory of the Riemann problem is used to derive a compact algebraic formula for the velocity of Rayleigh waves. Unlike previous results based on rationalization and Cardan’s solution of a cubic, the present formulation leads to a formula for the velocity which is a continuous function of the Poission’s ratio and yet is simple enough to be of practical interest. The new formula also enables us to express the complex roots associated with the Rayleigh wave equation as simple functions of the Rayleigh wave velocity. 相似文献
16.
应力波穿越岩石节理时能量耗散规律的实验研究 总被引:1,自引:0,他引:1
采用材料试验机和大尺度激光表面仪对大理岩和花岗岩两种岩石进行三点弯曲和粗糙断裂面的扫描实验,详细地分析了粗糙断裂面的分形特征。通过SHPB实验,研究并提出了波能量耗散与断裂面分形维数的定量关系;分析了分形维数对波能量耗散的影响规律。研究得出以下结论:1)随着粗糙断裂面分形维数的增大,通过断裂面时应力波能耗将相应增加;2)应力波能量主要是以热能和塑性变形能耗散。分形维数越大,比表面积则越大,粗糙表面粒子相互摩擦和挤压程度相应增加,导致波的机械能转化成热能和塑性变形能部分增加,因而波动能量耗散越大。 相似文献
17.
Surface roughness plays an important role in the delamination wear caused by rough surface contact. A recent dislocation model
analysis predicts that nano-scale contacts of surface steps induce nucleation of dislocations leading to pro-load and anti-load
dislocation segregation near the contact surface. Such dislocation segregation generates a sub-layer of tensile residual stress
in a much thicker layer of compressive residual stress near the surface. The tensile sub-layer thickness is expected to be
about 50 to 100 times the step height. In order to verify the predictions of the model analysis, contact experiments are carried
out on polycrystalline aluminum surface to determine the existence of the tensile sub-layer. The variation of the residual
stress along the thickness direction is measured using a newly developed high sensitivity curvature-measurement interferometer.
The residual stress distribution measured with sub-nanometer spatial resolution indicates that contact loading leads to formation
of a highly stressed sub-layer of tensile residual stress within a much thicker layer of compressive residual stress. Implications
of tensile residual stress for delamination wear are discussed. 相似文献
18.
《Wave Motion》2020
The propagation and properties of Rayleigh waves on curved surfaces are investigated theoretically. The Rayleigh wave dispersion equation for propagation on a curved surface is derived as a parabolic equation, and its penetration depth is analyzed using the curved surface boundary. Reciprocity is introduced to model the diffracted Rayleigh wave beams. Simulations of Rayleigh waves on some canonical curved surfaces are carried out, and the results are used to quantify the influence of curvature. It is found that the velocity of the surface wave increases with greater concave surface curvature, and a Rayleigh wave no longer exists once the surface wave velocity exceeds the bulk shear wave velocity. Moreover, the predicted wave penetration depth indicates that the energy in the Rayleigh wave is transferred to other modes and cannot propagate on convex surfaces with large curvature. A strong directional dependence is observed for the propagation of Rayleigh waves in different directions on surfaces with complex curvatures. Thus, it is important to include dispersion effects when considering Rayleigh wave propagation on curved surfaces. 相似文献