Velocity Effect on Fast Fracture-Fracture Surface Formation Process

速度对快速断裂-断裂面形成过程的影响

• 批准号: 10450038
• 负责人: TAKAHASHI Kiyoshi
• 金额: $ 1.09万
• 依托单位: KYUSHU UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B).
• 财政年份: 1998
• 资助国家: 日本
• 起止时间: 1998 至 2000
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-10450038/
• 关键词: Brittle Fracture; Surface Roughness; Fracture Surface Analysis; Epoxy Resin; Stress Intensity Factor; Fracture Velocity; Acrylic Resin

Mechanical meaning of fracture velocity (V) on dynamic fracture was assessed in this research. Systematic experimental study was performed to understand the relationship between dynamic fracture toughness (K), fracture surface roughness (R) and V by dividing a fracture process into two parts, namely, acceleration and deceleration regions. Handmade dual focus high-speed camera (RIAM-DFC2) was used to measure K and V accurately, and a laser roughness mater was used to measure R.The following conclusions were obtained :(1) For tensile SEN specimens of an extruded PMMA of low molecular weight (10^4 order), annealing at 90℃, 24hrs increased V, K and R of the material. However, CT+SEN specimens didn't show such annealing effect. Thus, specimen geometry dependence of the annealing effect was recognized.(2) CT+SEN type specimens of an epoxy resin and a low molecular weight PMMA exhibited that the peak of V appears prior to that of K, thus there exists time difference between the peaks of V and K, and the difference increases as the distance between crack and loading point increases. It was also shown that the peak of unloading rate lies between the two peaks of V and K.(3) Dynamic fracture experiment of a low molecular weight PMMA using a SEN specimen with circular holes enabled us to study the increase, decrease and reincrease processes of V and K.This experiment showed that in the fracture process, K is not a single-valued function of V and depends upon the acceleration (A).(4) It was clarified that if K and V are the same at different acceleration and reacceleration points, A values are almost identical. This implies that the relationship between K and V can be expressed explicitly by introducing A.(5) It was clarified that in dynamic fracture of low molecular weight PMMA, about a half of external work is converted into fracture energy.

探讨了断裂速度（V）在动态断裂中的力学意义.通过将断裂过程分为加速区和减速区，系统地研究了动态断裂韧性（K）、断裂表面粗糙度（R）与V之间的关系。结果表明：（1）对于低分子量（10^4级）PMMA挤出拉伸SEN试样，90℃退火24小时，材料的V、K和R均有所增加;而CT+SEN试样则没有这种退火效应。因此，试样的退火效应的几何形状的依赖性是公认的。(2)环氧树脂和低分子量PMMA的CT+SEN型试样的V峰先于K峰出现，因此V峰与K峰之间存在时间差，且随着裂纹与加载点距离的增大，时间差增大。卸载速率的峰值位于V和K的两个峰值之间。(3)利用带有圆孔的SEN试样对低分子量PMMA进行动态断裂实验，研究了V和K的增加、减少和再增加过程。实验表明，在断裂过程中，K不是V的单值函数，而是与加速度（A）有关。(4)澄清了如果K和V在不同的加速和再加速点相同，则A值几乎相同。这意味着K和V之间的关系可以通过引入A来显式地表达。(5)阐明了在低分子量PMMA的动态断裂中，约一半的外功转化为断裂能。

项目成果

新川和夫,馬田俊雄,高橋清: "高速破壊における動的応力拡大係数とき裂速度・加速度の相関関係について"日本機械学会論文集(A編). 66.645. 883-887 (2000)

Kazuo Shinkawa、Toshio Umada、Kiyoshi Takahashi：“关于高速断裂中的动态应力强度因子和裂纹速度/加速度之间的相关性”，日本机械工程师学会会议记录（编辑 A）66.645。 ）

G.Aggag and K.Takahashi: "Determination of stress-optical constant and dynamic fracture toughness of polycarbonate at high strain rate"Proc.7th Cairo Univ. Int. MDP Conf.. 123-130 (2000)

G.Aggag 和 K.Takahashi：“高应变率下聚碳酸酯的应力光学常数和动态断裂韧性的测定”Proc.7th Cairo Univ。

K.Takahashi: "Ductility enhancement of polymeric materials under low velocity impact"Proc.7th Int.Symp.on Plasticity and Its Current Applications. 975-978 (1999)

K.Takahashi：“低速冲击下聚合材料的延展性增强”Proc.7th Int.Symp.on 塑性及其当前应用。

K.Takahashi: "From recent studies on impact fracture of polymers and polymer composites"Key Engineering Materials. 183-187. 229-240 (2000)

K.Takahashi：“聚合物和聚合物复合材料冲击断裂的最新研究”关键工程材料。

M.Todo, K.Arakawa and K.Takahashi: "Nolinear displacement field in the vicinity of notch-tip in rubber toughened PMMA"Key Engineering Materials. 183-187. 409-414 (2000)

M.Todo、K.Arakawa 和 K.Takahashi：“橡胶增韧 PMMA 中缺口尖端附近的非线性位移场”关键工程材料。