Dynamic caustics and its applications (EN)

Papadopoulos, GA (EN)

For the study of elastodynamic problems of propagating cracks it is necessary to evaluate the dynamic stress intensity factor KdI which depends on the form of expressions for the stress components existing at the running crack tip at any instant of the propagation of the crack and the corresponding dynamic mechanical and optical properties of the material of the specimen under identical loading conditions. In this paper the distortion of the form of the corresponding reflected caustic from the lateral faces of a dynamically loaded transparent and optically inert specimen containing a transverse crack running under constant velocity was studied on the basis of complex potential elasticity theory and the influence of this form on the value of the dynamic stress intensity factor was given. The method was applied to the study of a propagating Mode I crack in a PMMA specimen under various propagation velocities and the corresponding dynamic stress intensity factor KdI evaluated. Also, crack propagation behaviour of notched composites in dynamic loading modes are reviewed and evaluated. A relatively large data base using metal-epoxy particulates, rubber-toughened poly(methyl methacrylate), and Sandwich plates are given. In all cases, a combination of high-speed photography and the optical method of dynamic caustics has been used. Results on the dynamic crack propagation mode, fracture toughness and crack propagation velocities of several rubber-modified composite models are presented. The composite models studied include specimens with one and/or two 'complex' two-stage inclusions, i.e. PMMA round inclusions surrounded by concentric rubber rings, one and/or press-fifting inclusions without rubber interface, all under dynamic loading. In all cases both qualitative and quantitative results were obtained. Also, results on crack propagation mode, crack propagation velocity, stress intensity factors and on the influence of the sandwich phases on crack propagation mode are presented. © 1990. (EN)

journalArticle (EN)

Composite Materials (EN)

Notched Composites (EN)

PMMA Round Inclusions (EN)

Press-Fitting Inclusions (EN)

Fracture Mechanics (EN)

Concentric Rubber Rings (EN)

Optics (EN)

Dynamic Caustics (EN)

Rubber (EN)

Stress Intensity Factor (EN)

National Technical University of Athens

Digital Library of National Technical University of Athens | Dspace@NTUA

Κεντρική Βιβλιοθήκη Ε.Μ.Π.

Ιδρυματικό Αποθετήριο

Δημοσιεύσεις μελών Δ.Ε.Π. σε περιοδικά

Optics and Lasers in Engineering (EN)

English

1990 (EN)

http://hdl.handle.net/123456789/10213

ISI:A1990EE66600003 (EN)

13 (EN)

211 (EN)

249 (EN)

3-4 (EN)

0143-8166 (EN)

ELSEVIER SCI LTD (EN)