Grant-in-Aid for Scientific Research (C).
Materials/Mechanics of materials
|Research Institution||Osaka City University|
MOTOGI Shinya Osaka City University, Department of Intelligent Materials Engineering, Professor, 工学部, 教授 (40221626)
|Project Fiscal Year
1998 – 2000
Completed(Fiscal Year 2000)
|Budget Amount *help
¥3,400,000 (Direct Cost : ¥3,400,000)
Fiscal Year 2000 : ¥300,000 (Direct Cost : ¥300,000)
Fiscal Year 1999 : ¥600,000 (Direct Cost : ¥600,000)
Fiscal Year 1998 : ¥2,500,000 (Direct Cost : ¥2,500,000)
|Keywords||Damage / Composite materials / Ultrasonic nondestructive evaluation / Damage mechanics / Constitutive equation / Lamb wave / Random particulate camposites / Interfacial cracking damage / 損傷 / 複合材料 / 超音波による非破壊評価 / 損傷力学 / 構成式 / 板波 / 粒子分散複合材料 / 界面はく離損傷 / 非破壊評価 / 超音波板波|
In this research, two types of damage are focused on ; one is the transverse cracking damage in FRP crossply laminates, the other is particle-matrix interfacial cracking damage. For the transverse cracking in FRP, obtained results can be summarized as follows :
1) The average stress in cracking layer decreases with development od cracking, and then the constitutive equation of the cracking layer can be described by the so-called work-softening material.
2) The modern plasticity theory can be applied to the cracking layer and the uncracked layer can be regarded as anisotropic elastic material, then these are combined to give a laminate with the aid of lamination theory.
3) Using the above formulation, crack development and degradation of elastic stiffnesses are compared with experiments and give good correspondence.
4) Lamb wave velocity in damaged laminates can be calculated and a comparison with experiment was excellent.
For the interfacial cracking in random particulate composites is suumarized as follows :
1) A release agent can be used as the controller of the interfacial strength in making the material.
2) The stress-strain curve shows large nonlinearity because of development of interfacial cracking damage, and as a result, elongation at failure increases as the interfacial cracking strength decreases.
3) Wave propagation velocities and acoustic anisotropy are caculated and these also agrees well with experimental results.
These results are a base for nondestructive damage evaluation in composite materials, and they contribute to improvement in reliability of composites.