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1.
为研究钢筋混凝土梁板组合结构在长持时远爆冲击波荷载作用下的动力响应及毁伤形态,通过实验获得了梁板组合结构的破坏形态和背爆面中心点位移变化。利用有限元软件对钢筋混凝土梁板组合结构的动态响应过程进行数值模拟研究,模拟得到的结构破坏现象与实验吻合较好。在此基础上,分析了梁板组合结构在相同冲量、不同峰值爆炸荷载作用下组合结构的动态响应和破坏过程,并结合挠跨比与破坏形态划分破坏模式。研究结果表明,相同冲量作用下,随着爆炸荷载峰值强度增加,梁板组合构件的破坏程度逐渐增加,破坏模式从弯曲破坏向弯剪联合破坏转换,最后呈现冲切破坏模式;组合构件中板部分发生破坏的时间早于交叉梁部分、破坏程度大于交叉梁。  相似文献   

2.
含损伤演化的TM耦合数值模型及其应用研究   总被引:3,自引:0,他引:3  
从岩石材料的细观结构层次出发,应用损伤力学和热弹性理论,对热力耦合作用下岩石破裂 过程中热-应力相互作用关系进行了分析. 初步建立了细观岩石热-力(TM)耦合数值模型, 探讨了TM耦合作用下岩石材料的细观结构损伤及其诱发的材料力学性能演化机制,把岩石 热固耦合问题的研究从应力状态分析深入到损伤、破坏过程分析之中. 运用该数值模型对某 硬岩实验室开展的原位尺度实验中的废料处理井间柱稳定性进行了模拟分析,其应力场、岩 石剥离破坏形态及破坏诱发的AE特性等均与实验监测结果表现出了较好的一致性,证 明了该数值模型的合理性和有效性.  相似文献   

3.
利用MSC.Dytran中的具有强度的多材料欧拉网格模拟水滴和有限长连续射流对靶板 (岩石)的高速冲击作用,研究了靶板破坏深度、破坏宽度与水滴初压力、速度、入射方向、 板厚以及连续射流的密度等的关系及其物理意义. 用应力波理论来解释靶板的层裂现象,试 图多角度分析射流破岩机理.  相似文献   

4.
应用数值试验方法,推进岩石力学实验的教学   总被引:7,自引:1,他引:6  
 把岩石破坏过程分析数值模拟系统RFPA引入岩石力学实验课程的教学,进行岩石变形 与破裂过程的数值试验. 数值试验可以再现许多物理实验所不能观察到的力学现象(例如 岩石破裂过程中的应力场),从而使学生对岩石的变形与破坏过程有更加清晰的认识,提高岩 石力学实验的教学质量.  相似文献   

5.
二阶非定常多宗量热传导反问题的正则解   总被引:1,自引:0,他引:1  
薛齐文  杨海天 《力学学报》2007,39(6):774-780
引入Bregman距离函数及其加权函数作为正则项,应用Tikhonov正则 化方法,对二阶非定常多宗量热传导反问题进行求解. 利用测量信息和计算信息构造最小二 乘函数,将多宗量反演识别问题转化为一个优化问题. 空间上采用8节点等参元进行离散, 时域上采用时域精细算法进行离散,建立了二阶非定常多宗量热传导问题的有限元正/反演数 值模型. 该模型不仅考虑了非均质和参数分布的影响,而且也便于正反演问题的敏度分析, 可对导热系数和边界条件等宗量进行有效的单一和组合识别. 给出了相关的数值验证,对信 息测量误差以及不同正则项的计算效率作了探讨. 数值结果表明,该方法能够对二阶非定常 多宗量热传导反问题进行有效的求解,并具有较高的计算精度.  相似文献   

6.
引入Bregman距离加权函数,建立了多宗量瞬态热传导反演的一种求解模式.时域上采用精细算法,分别建立了便于敏度分析的有限元正/反演模型,应用同伦算法进行反问题求解,对导热系数和边界条件等宗量进行有效的组合识别.对信息误差和计算效率作了探讨,并给出了相应的数值验证.  相似文献   

7.
脆性材料内部含有大量裂纹,当某一裂纹扩展时,其他裂纹会对扩展裂纹产生影响。为了研究冲击载荷下,脆性材料内两裂纹的相互影响、连通规律及裂纹尖端应力强度因子的变化规律,利用有机玻璃板制作了含非平行双裂纹的实验试件,利用落板冲击设备进行了中低速冲击实验,结合有限元分析软件ABAQUS计算出裂纹尖端应力强度因子,利用有限差分软件AUTODYN进行了动态数值模拟研究,并将其模拟结果与实验结果进行对比分析。实验及模拟结果表明:裂纹破坏形态与AUTODYN数值模拟破坏形态基本一致;试件的断裂形态随着两裂纹间距不同而不同;裂纹间的相互影响程度随着裂纹间间距增大而减小;裂纹尖端应力强度因子KI随着裂纹间距的增大而减小,而KII随着裂纹间距增大而增大。  相似文献   

8.
水射流辅助破岩机理研究(1)--气泡空蚀   总被引:1,自引:0,他引:1  
利用MSC. Dytram软件中的具有强度的多材料欧拉网格模拟了高速运动气泡对靶板(岩石)的冲击过程,研究了靶板破坏深度、破 坏宽度与气泡初始压力、速度以及入射方向等的关系,试图指出这些关系的物理意义并分析射流破岩机理.  相似文献   

9.
数值试验是认识岩土材料细观与宏观力学行为的一种重要手段,是常规岩土力学实验的补充和延伸.本文以pfc颗粒流为平台,利用matlab和fish语言混合编程编写了岩土力学虚拟实验仿真系统,系统根据获取的岩土材料天然结构构造图像信息,可以生成含不同天然结构构造信息的岩土体试件.可以对不同规格试件实现伺服加卸载,可以监测任意点的应力应变信息,可以捕捉试件加卸载过程中的边界输入能量和摩擦能、动能及应变能的转换信息,捕捉试件的最终破坏形态和破坏过程中裂纹扩展信息及不同类型裂纹的数量演化信息.利用其可以研究岩土材料天然结构构造特征对其宏观、细观力学行为的影响.  相似文献   

10.
???????????????ü????????????????????   总被引:1,自引:0,他引:1  
基于应用影响线函数由监测效应反演荷载的理论分析,提出了通过构造监测截面监测力 学量影响线函数,建立监测力学量与桥上车辆荷载的关系式,应用监测信息反演过桥车 辆荷载的荷载识别方法. 实例结果表明该方法能有效地识别桥上车辆荷载载重.  相似文献   

11.
将应变模态作为实测资料应用概率方法进行结构损伤定位.采用的模态误差考虑了建模误差和测量误差等不确定因素,避免了测量自由度与模型自由度不匹配的问题.研究了损伤状态搜索策略,并对应变模态和位移模态分别作为实测资料的定位结果进行了比较,表明采用应变模态具有更高的定位精度.  相似文献   

12.
Thermodynamics of the damage and the healing processes for viscoplastic materials is discussed in detail and constitutive equations for coupled inelastic-damage-healing processes are proposed in a thermodynamic consistent framework. Small deformation state is utilized and the kinematic and the isotropic hardening effects for the damage and healing processes are introduced into the governing equations. Two new yield surfaces for the damage and healing processes are proposed that take into account the isotropic hardening effect. The computational aspect for solving the coupled elasto-plastic-damage-healing problem is investigated, and the mechanical behavior of the proposed polymeric based self healing system is obtained. Uniaxial compression tests are implemented on a shape memory polymer based self healing system and the damage and the healing are captured by measurement of the changes in the modulus of elasticity. It is concluded that the proposed constitutive equations can model the damage and healing effectively and the mechanical behavior of a shape memory polymer based self healing system can be precisely modeled using this formulation.  相似文献   

13.
??????e???????????????????????   总被引:12,自引:0,他引:12  
 用基于X射线的CT无损检测技术进行岩石损伤检测是岩石损伤力学的重要 研究方向之一. 首先介绍X射线CT设备的发展状况、检测原理和技术指标,回顾了CT 技术在岩石损伤检测中的应用进展,其次给出了现有的CT分析方法, 提出了统计频率分析法;然后评价了各种基于CT均值的损伤变量;最后指出岩石CT技术目 前存在的问题,并预测了未来的发展方向.  相似文献   

14.
X射线CT技术在岩石损伤检测中的应用研究   总被引:2,自引:0,他引:2  
用基于X射线的CT无损检测技术进行岩石损伤检测是岩石损伤力学的重要研究方向之一,首先介绍X射线CT设备的发展状况、检测原理和技术指标,回顾了CT技术在岩石损伤检测中的应用进展,其次给出了现有的CT分析方法,提出了统计频率分析法;然后评价了各种基于CT均值的损伤变量;最后指出岩石CT技术目前存在的问题,并预测了未来的发展方向。  相似文献   

15.
Based on a micromechanical concept of void growth and change in void shape, a dissipation potential and constitutive equations for ductile damage of metals are presented. Multiplicative decomposition of the metric transformation tensor and thermodynamic formulation of the constitutive equations lead to a symmetric second-order tensor of damage which is physically meaningful. Its first invariant defines the damage related to plastic dilatation of the material due to the void growth. The second invariant of the deviatoric tensor accounts for the damage associated with a change in the void shape. Two physically motivated normalized measures allow us to represent the kinetic process of strain-induced damage by using the equivalent parameter of damage including the limit conditions for the onset of void coalescence and ductile failure. An experimental analysis of the evolution of ductile damage is presented for the case of uniaxial tension of sheet steel specimens with artificial defects.  相似文献   

16.
以形状随时间变化的物体——时变体为研究对象,将损伤理论与时变力学结合,引入与时变过程相关的损伤参数,形成损伤时变力学分析方法。针对岩石介质特性给出了弹性损伤时变力学本构方程,并利用虚功原理建立相应数值化方法和分析过程。利用损伤时变力学分析方法对某地下煤层开采过程进行计算机仿真分析,给出形状时变引起的损伤场与地表移动的动态演化过程,并对比了非时变以及施工分析结果。研究表明,损伤时变分析可得到连续变化的位移及损伤演化图,相比非时变的常规分析和施工分析能更好地模拟连续施工,为工程施工分析与预测提供更加科学和有效的手段。为实现开采过程的经济和安全,应该采用损伤时变力学的分析方法。  相似文献   

17.
18.
A new damage detection technique using irregularity profile of a structural mode shape is proposed in this paper. The mode-shape of a cracked beam is first obtained analytically by using a general function. Its irregularity profile is then extracted from the mode shape by a numerical filter. The location and size of the crack in the beam can be determined by the peak value appearing on the irregularity profile. Two types of numerical filters, i.e., triangular and Gaussian, are examined. It has been found that the former filter is more effective in damage detection than the latter one. Numerical simulations suggest that the irregularity-based method requires a relatively low measurement resolution. Noise stress tests are carried out to demonstrate the effectiveness and robustness of this method under the influence of noise. As a validation, the proposed method is applied to detect crack damage in an E-glass/epoxy laminated composite beam. The successful detection of the crack in the composite beam demonstrates that the irregularity-based method is capable of assessing both the location and size of the crack and can be used efficiently and effectively in damage identification and health monitoring of beam-type structures.  相似文献   

19.
A combined physico-mechanical approach to research and modeling of forming processes for metals with predictable properties is developed. The constitutive equations describing large plastic deformations under complex loading are based on both plastic flow theory and continuum damage mechanics. The model which is developed in order to study strongly plastically deformed materials represents their mechanical behavior by taking micro-structural damage induced by strain micro-defects into account. The symmetric second-rank order tensor of damage is applied for the estimation of the material damage connected with volume, shape, and orientation of micro-defects. The definition offered for this tensor is physically motivated since its hydrostatic and deviatoric parts describe the evolution of damage connected with a change in volume and shape of micro-defects, respectively. Such a representation of damage kinetics allows us to use two integral measures for the calculation of damage in deformed materials. The first measure determines plastic dilatation related to an increase in void volume. A critical amount of plastic dilatation enables a quantitative assessment of the risk of fracture of the deformed metal. By means of an experimental analysis we can determine the function of plastic dilatation which depends on the strain accumulated by material particles under various stress and temperature-rate conditions of forming. The second measure accounts for the deviatoric strain of voids which is connected with a change in their shape. The critical deformation of ellipsoidal voids corresponds to their intense coalescence and to formation of large cavernous defects. These two damage measures are important for the prediction of the meso-structure quality of metalware produced by metal forming techniques. Experimental results of various previous investigations are used during modeling of the damage process.   相似文献   

20.
用电阻量测方法研究蠕变状态下的金属损伤   总被引:3,自引:0,他引:3  
本文建议一种量测蠕变下金属损伤的方法。与其它方法相比,这个方法可用于进行在蠕变试验过程中的损伤测量,而无需使试件卸载或冷却。用此方法对试验数据进行加工就可得到在蠕变过程中的试验损伤曲线。对这些曲线的分析导致结论:材料破坏时的损伤是所加应力的递减函数。这一结论是以前所得理论结果的试验验证。  相似文献   

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