共查询到20条相似文献,搜索用时 203 毫秒
1.
运用金属材料表面纳米化试验机对单个弹丸撞击316L不锈钢表面进行了撞击实验;采用激光共聚焦显微镜观察了弹坑的三维形貌,测量不同振动频率下弹坑的直径及离面位移;采用云纹干涉法对弹坑周围的面内应变场进行测量,并分析振动频率及撞击方式对弹坑尺寸、塑性应变大小以及塑性应变区范围的影响;采用有限元方法对单个弹丸垂直撞击试件表面的应变场进行数值模拟,与实验结果进行比较,分析了弹坑周围残余应力的分布。结果表明:随振动频率的增加,弹坑直径和离面位移都增加,频率在50~55Hz,弹坑直径有突变,离面位移和振动频率呈线性关系;振动频率越大,塑性应变越大,塑性应变分布范围均大于弹坑直径的2倍;同一振动频率下弹丸垂直撞击比倾斜撞击的塑性应变大,而塑性应变分布范围相差不大;面内残余应变场的数值模拟结果和实验结果吻合较好,最大误差小于10%。 相似文献
2.
3.
4.
5.
本文根据广义弹脆性损伤理论模型,用综合实验分析和数值计算的方法,确定受载复合材料板的形变场和损伤场。首先用云纹干涉法确定各受损单元的节点位移,再用有限元分析得到这些单元的真实应变和有效应变。由此计算受载各单元的损伤变量和有效弹性系数。最后,根据弹脆性材料的损伤本构关系确定受载复合材料板的真实应力场。 相似文献
6.
7.
采用阴影云纹和应变片方法对伪弹性TiNi合金圆板在固支条件下的准静态力学行为进行了实验研究,得到了载荷位移曲线、全场离面位移和局部应变等数据.载荷位移曲线呈现非线性、滞回耗能和无残余变形的特性,表明试样已经发生马氏体相变.应变测量显示,相变局限于加载中心较小区域,相变区内,环向应变大于径向应变,且拉伸侧应变大于压缩侧的应变.有限元模拟揭示出相变区内两侧表层的相变范围、相变铰区和马氏体相含量的不对称分布规律. 相似文献
8.
本文用统计光学方法对双参考光全息——散斑干涉术进行了详尽的理论分析,给出了全息和散斑干涉场区域平均光强分布与光学系统主要参数及三维变形场各分量之间关系的解析表达式,进而讨论了离面位移和面内位移测量的上、下限,最后还给出了有关的实验结果。 相似文献
9.
10.
11.
The hole-drilling method is one of the most wellknown methods for measuring residual stresses. To identify unknown plane stresses in a specimen, a circular hole is first drilled in the infinite plate under plane stress, then the strains resulting from the hole drilling is measured. The strains may be acquired from interpreting the Moire signature around the hole. In crossed grating Moire interferometry, the horizontal and vertical displacement fields (u and v) can be obtained to determinate two strain fields and one shearing strain field. In this paper, by means of Moire interferometry and three directions grating (grating rosette) developed by the authors, three displacement fields (u, v and s) are obtained to acquire three strain fields. As a practical application, the hole-drilling method is adopted to measure the relief strains for aluminum and fiber reinforced composite. It is a step by step method; in each step a single laminate or equivalent depth is drilled to find some relationships between the drilling depth and the residual strains relieved in the fiber reinforced composite materials. 相似文献
12.
本文利用变角度复合材料的纤维方向角可沿平面位置任意连续变化的特点,提出在孔附近采用与孔同心的椭圆曲线作为纤维铺设路径的层合板铺层方案,以改善含椭圆孔的层合板的孔边应力集中,进而提高层合板的抗屈曲性能.主要研究内容有:利用ABAQUS软件分析本文提出的孔边特殊铺层方式下变角度复合材料层合板的面内应力分布及屈曲性能,通过与传统直线铺层方式以及线性变角度铺层方式进行比较,说明了本文提出的新铺层方式的优越性,并详细分析了椭圆孔的离心率、开孔尺寸及开孔方位对层合板的屈曲临界荷载的影响.研究结果可为含椭圆孔的变角度复合材料层合板的结构设计和优化提供一定的参考. 相似文献
13.
14.
15.
16.
提出的一种缝合线计算模型,通过数值模拟计算与实验结果比较,得到缝合线计算模型中相关的弹性参数.对复合材料开口缝合补强结构进行有限元模拟计算,分析了孔边及邻近区域应变、应力的分布规律,得到不同缝合参数、孔边不同位置以及不同载荷条件下的应变、应力集中系数,并给出合理的孔口缝合参数设计方法及相关结论.研究结果表明:含孔拉伸试件在孔边θ=0°处,切向拉伸应力最大;在θ=90°处,切向压缩应力最大;在孔口0°和90°之间存在拉应力与压应力的转换点,缝合补强后,此转换点大约在θ=56°左右. 相似文献
17.
《International Journal of Solids and Structures》2003,40(5):1139-1164
A fracture mechanics based failure criterion for unidirectional composites under combined loading has been developed. The predictions from this criterion have been compared with experimental data obtained from combined compression–torsion loading of glass and carbon fiber reinforced polymer composites of 50% fiber volume fraction. The specimens were loaded under rotation control and displacement control in a proportional manner. Comparison of the Budiansky–Fleck kinking model, specialized to a solid circular cylinder, and the new failure model against experimental data suggests that the Budiansky–Fleck model predictions do not capture the variation of compressive strength as a function of shear stress for glass fiber composites. This is because these composites fail predominantly by compressive splitting. The Budiansky–Fleck model predictions are appropriate for composites that fail by compressive kinking. The new model predictions capture the experimental results for glass composites where the compression strength is initially unaffected by shear stress but undergoes a drastic reduction when a critical value of shear stress is reached. 相似文献
18.
对单轴压缩下两种密度的泡沫铝进行了三种频率(50kHz、200kHz和300kHz)的声波测试,同时运用CCD对实验进行跟踪拍摄。分析结果表明:P波波速随载荷增大而增加,当载荷达到屈服力时,波速有所下降;S波有相同趋势,但变化比P波小。应用数字图像相关方法对CCD拍摄图片进行处理,得到不同载荷阶段下泡沫铝的全场应变;采用Weibull函数对全场应变分布进行拟合,研究了Weibull分布参数随载荷变化的规律。由此,初步建立了载荷作用下材料结构变化与波速的关系。此研究对于声波探测领域有很好的指导意义。 相似文献
19.
玻璃纤维增强尼龙1010复合材料的摩擦学性能研究 总被引:23,自引:8,他引:15
利用WZM-1微型注塑机制备了玻璃纤维增强尼龙复合材料,在环-块摩擦磨损试验机上考察了玻璃纤维含量和试验条件下对其摩擦学性能的影响,并利用扫描电子显微镜对其磨损机理进行了分析。结果表明:在给定试验条件下玻璃纤维含量对复合材料的摩擦学性能有显著影响,玻璃纤维质量分数介于25%~30%之间时增强效果较好;复合材料的摩擦系数随载荷的增加而下降,达到最小值后,又随载荷的增加而持续上升;其磨损质量损失则随载荷的增加而持续增大,复合材料的磨损以粘着磨损为主,随载荷的增加转变为以玻璃纤维的破坏和磨平为主。 相似文献
20.
《International Journal of Solids and Structures》2007,44(24):7731-7747
In the present paper results of a series of plate impact experiments designed to study spall strength in glass–fiber reinforced polymer composites (GRP) are presented. Two GRP architectures are investigated—S2 glass woven roving in Cycom 4102 polyester resin matrix and a balanced 5-harness satin weave E-glass in a Ciba epoxy (LY564) matrix. The GRP specimens were shock loaded using an 82.5 mm bore single-stage gas-gun. A velocity interferometer was used to measure the particle velocity profile at the rear (free) surface of the target plate. The spall strength of the GRP was obtained as a function of the normal component of the impact stress and the applied shear-strain by subjecting the GRP specimens to normal shock compression and combined shock compression and shear loading, respectively. The spall strengths of the two GRP composites were observed to decrease with increasing levels of normal shock compression. Moreover, superposition of shear-strain on the normal shock compression was found to be highly detrimental to the spall strength. The E-glass reinforced GRP composite was found to have a much higher level of spall strength under both normal shock compression and combined compression and shear loading when compared to the S2-glass GRP composite. The maximum spall strength of the E-glass GRP composite was found to be 119.5 MPa, while the maximum spall strength for the S2 glass GRP composite was only 53.7 MPa. These relatively low spall strength levels of the S2-glass and the E-glass fiber reinforced composites have important implications to the design and development of GRP-based light-weight integral armor. 相似文献