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1.
Polycrystalline ceramics have heterogeneous meso-structures which result in high singularity in stress distribution. Based on this, a progressive fragment model was proposed which describes the failure wave formation and propagation in shocked ceramics. The governing equation of the failure wave was characterized by inelastic bulk strain with material damage and fracture. And the inelastic bulk strain consists of dilatant strain from nucleation and expansion of microcracks and condensed strain from collapse of original pores. Numerical simulation of the free surface velocity was performed in good agreement with planar impact experiments on 92.93% aluminas at China Academy of Engineering Physics. And the longitudinal, lateral and shear stress histories upon the arrival of the failure wave were predicted, which present the diminished shear strength and lost spall strength in the failed layer. 相似文献
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纤维板增强钢筋砼缺口梁承载力试验研究 总被引:6,自引:1,他引:6
通过对8组24根碳纤维薄板增强钢筋混凝土梁进行三点弯曲试验,探讨碳纤维薄板增强钢筋混凝土缺口梁的破坏过程、极限承载力及其影响因子.研究结果表明:1)碳纤维薄板增强钢筋混凝土缺口梁总是沿着纤维薄板与混凝土的界面发生剥高破坏;2)与无增强梁相比,增强梁的极限来载力可以提高20%一40%.而且当纤维薄板贴长Lc与两支点间距离S之比为0.57左右时增强效果最明显;3)缺口对梁的破坏模式影响较大,而对梁的极限承载力影响不大(下降10%-15%). 相似文献
3.
Based on the precise integration method(PIM), a coupling technique of the high order multiplication perturbation method(HOMPM) and the reduction method is proposed to solve variable coefcient singularly perturbed two-point boundary value problems(TPBVPs) with one boundary layer. First, the inhomogeneous ordinary diferential equations(ODEs) are transformed into the homogeneous ODEs by variable coefcient dimensional expansion. Then, the whole interval is divided evenly, and the transfer matrix in each sub-interval is worked out through the HOMPM. Finally, a group of algebraic equations are given based on the relationship between the neighboring sub-intervals, which are solved by the reduction method. Numerical results show that the present method is highly efcient. 相似文献
4.
Based on the precise integration method (PIM), a coupling technique of the high order multiplication perturbation method (HOMPM) and the reduction method is proposed to solve variable coefficient singularly perturbed two-point boundary value prob lems (TPBVPs) with one boundary layer. First, the inhomogeneous ordinary differential equations (ODEs) are transformed into the homogeneous ODEs by variable coefficient dimensional expansion. Then, the whole interval is divided evenly, and the transfer ma trix in each sub-interval is worked out through the HOMPM. Finally, a group of algebraic equations are given based on the relationship between the neighboring sub-intervals, which are solved by the reduction method. Numerical results show that the present method is highly efficient. 相似文献
5.
正交异性板复合型裂纹相对周向应力断裂准则 总被引:2,自引:0,他引:2
采用相对周向应力为断裂参数,提出正交异性板任意方向的Ⅰ-Ⅱ复合型裂纹的最大相对向应力断裂,准则,应用本准则确定开裂方向角时,能较合理地考虑材料特性的影响。 相似文献
6.
碳纤维板增强钢筋砼梁开裂性状试验研究 总被引:6,自引:0,他引:6
采用实验研究的方法,对碳纤维薄板增强钢筋混凝土三点弯曲缺口梁和无缺口梁的开裂性状及破坏规律进行探讨,分析其影响因子,研究结果表明:1)与无纤维板增强钢筋混凝土梁相比,碳纤维薄板增强钢筋混凝土三点弯曲梁的开裂性状和破坏模式更加复杂,开裂荷载和极限荷载提高,刚度增加;2)与无缺口梁相比,缺口梁的开裂性状大致相同,但开裂荷载和极限荷载都稍有下降,刚度增加;3)碳纤维薄板的粘贴长度对梁的开裂性状、开裂荷载、极限荷载和刚度有较大的影响;4)按照梁的不同的开裂性状,提出了相应的力学分析模型。 相似文献
7.
This paper presents a high order multiplication perturbation method for sin- gularly perturbed two-point boundary value problems with the boundary layer at one end. By the theory of singular perturbations, the singularly perturbed two-point boundary value problems are first transformed into the singularly perturbed initial value problems. With the variable coefficient dimensional expanding, the non-homogeneous ordinary dif- ferential equations (ODEs) are transformed into the homogeneous ODEs, which are then solved by the high order multiplication perturbation method. Some linear and nonlinear numerical examples show that the proposed method has high precision. 相似文献
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9.
随机载荷下碳纤维薄板增强RC梁试验研究 总被引:2,自引:0,他引:2
桥梁等钢筋混凝土结构在运营期所受活载为随机载荷。研究随机载荷作用下碳纤维薄板(Carbon Fiber Laminate简称CFL)片材增强钢筋混凝土构件的疲劳性能,对于采用碳纤维薄板技术加固桥梁等混凝土结构有重要的指导意义。本文通过随机载荷作用下碳纤维薄板增强RC梁的三点弯曲疲劳试验,得到了增强梁的S-N曲线和跨中挠度的演化规律,揭示了随机载荷下增强梁的疲劳破坏机理。随机载荷下碳纤维薄板增强RC梁的破坏模式包括钢筋断裂、碳纤维薄板剥离、混凝土压坏等破坏形态,疲劳破坏过程具有明显的损伤成核、稳定扩展、失稳扩展的三阶段发展规律。 相似文献
10.
压剪复合冲击下氧化铝陶瓷的剪切响应实验研究 总被引:4,自引:0,他引:4
通过对92.93%氧化铝陶瓷进行倾斜板碰撞实验,研究了多晶陶瓷材料在压剪复合冲击下的非弹性变形响应和剪切波传播规律。压剪复合冲击实验由57 mm开槽气体炮驱动铜飞片对陶瓷靶板加载,通过试件内埋植的电磁速度计来测量内部质点速度历程。将纵向粒子速度从感应电动势曲线中分离后得到横向粒子速度历程,发现在压剪复合冲击下由于材料剪切刚度的降低而引起的剪切波衰减。冲击软回收试件的扫描电子显微镜(SEM)观察表明,冲击载荷低于屈服强度时,多晶氧化铝陶瓷中存在沿晶界、气孔的微裂纹成核与扩展,在高于屈服强度的冲击加载下进一步产生了穿晶微裂纹,微裂纹系统导致了材料在卸载后的显著的体积膨胀。 相似文献