Fracture micromechanics of polymer materials PDF
Preview Fracture micromechanics of polymer materials
Fracture micro mechanics of polymer materials Series on Fatigue and Fracture VOLUME I S. Kocanda - Fatigue failure of metals VOLUME II V. S. Kuksenko and V. P. Tamuzs - Fracture micromechanics of polymer materials Fracture micromechanics of polymer materials V. s. Kuksenko and V. P. Tamuzs I I 1981 SPRlNGER-SCIENCE+BUSINESS MEDIA, B.Y. Library of Congress Catalog Card Number: 81-50357 ISBN 978-90-481-8270-1 ISBN 978-94-017-1597-3 (eBook) DOI 10.1007/978-94-017-1597-3 Copyright © 1981 by Springer Science+Business Media Dordrecht Originally published by Martinus Nijhojj Publishers bY, The Hague in 1981 Softcover reprint of the hardcover 1s t edition 1981 All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, mechanical, photocopying, recording, or otherwise, without the prior written permission of the publisher, Springer-Science+Business Media, B. V. Fatigue and fracture Editorial Board Editor-in-Chief: Professor George C. Sih Lehigh University Bethlehem, Pa. USA Members: Dr. David Broek Battelle Columbus Laboratories Columbus, Ohio USA Professor Dominique Francois Universite de Technologie de Compiegne Compiegne, France Professor Hiroyuki Okamura University of Tokyo Tokyo, Japan Dr. Erwin Sommer Institut fiir Festkorpermechanik Freiburg, West Germany Dr. Harry C. van Elst Metal Research Institute TNO Apeldoorn, The Netherlands Fatigue and Fracture Fatigue and fracture encompass a great many disciplines involving physics, chemistry, continuum mechanics, materials testing and structural analysis. Because of the large number of publications, the analytical and experi mental complexities, and the variety of phenomena and materials encoun tered, it becomes necessary to provide a medium for disseminating per tinent technical material, data, and information on an organized basis. This new series is devoted to the advancement of theoretical know ledge and practical understanding of fatigue and fracture. It intends to strike a balance between material evaluation and structrual design. The ever-increasing demand for high performance structures has necessitated the revision of existing technical principles and the development of new ones. Admittedly, the problem of material failure cannot be completely avoided and will very likely always be with us. Encouraged, however, are contributions to the fundamental understanding and practical application of procedures for design, material selection and fabrication which, when combined into an integrated whole, should provide a better means of evaluating the safety and or reliability of modern engineering structures. The editorial board VII Contents Foreword XII Preface to the English edition XIV Editors preface XV 1 Changes in the mechanical properties of polymer and composite materials during the fatigue process 1.1 A brief survey of literature 2 1.2 Principles of experimental study 5 The measurement of strains, energy dissipation and temperature 8 1.3 Changes in the deformation properties of fiberglass plastics during cyclic loading . . . . 10 1.4 The energy dissipation in glass laminate during cyclic tension - compression 16 Shape and magnitude of the hysteresis loops 16 The ratio of mechanical to thermal losses of energy 17 The dependence of L~ W on durability 22 1.5 Changes in the mechanical properties and temperature during cyclic loading of thermoplastic polymer materials 23 1.6 Fatigue of fiberglass plastics under repeated impact loads 26 1.7 Recording of damage processes in fiberglass plastics by acoustic emission technique 29 2 The observations of continuum ruptures in polymers under load 33 2.1 X-ray scattering on density heterogeneities 33 2.2 Equipment for the measurement of small angle X-ray scattering 40 2.3 Experimental data processing 45 2.4 Separation of sub micro crack scattering 50 3 Regularities of submicrocrack origination in loaded polymers 61 3.1 The sizes and shapes of submicrocracks 62 3.2 Comparison of the shapes of submicro-and macrocracks 71 3.3 Accumulation of submicrocracks under different loading conditions 74 3.4 Submicrocrack concentrations in the prerupturing state 80 3.5 The effect of submicrocracks on the deformation of polymers 84 4 Structural conditions for submicrocrack generation 93 4.1 Structure of directed crystalline polymers and their behavior under load 94 4.2 Properties of amorphous interlayers in directed crystalline polymers 98 IX Contents 4.3 Comparison of sizes of structural elements and submicrocracks 107 4.4 Structural peculiarities of submicrocrack formation in non-directed polymers 111 5 Molecular mechanism of submicrocrack generation 115 5.1 Thermoftuctuational nature of submicrocrack formation 117 5.2 Ruptures of chemical bonds in loaded polymers 123 5.3 The role of chain processes in the origination of submicrocracks 131 5.4 The effect of ionizing radiations on the rate of submicrocrack origination 135 6 Localization of the fracture process 139 6.1 The concentration criterion for interaction and coalescence of submicro- cracks . 141 6.2 Enlargement of sub microcracks 149 6.3 The role of surface in fracture localization 153 6.4 The effect of sub microcracks on the origination and development of micro- and macrocracks 158 6.5 Localization levels and the main principles of polymer fracture micro- mechanics 163 7 A statistical model of the fracture of polymer materials 167 7.1 Some statistical theories of short-term strength 167 7.2 Fracture models under uniaxial loading 170 The measure of material damage 170 Lifetime analysis with statistical overstress distribution 174 7.3 The statistical model of fracture kinetics to materials with heterogeneous structure 180 Principle hypotheses of the model 180 Calculation and discussion of results 184 8 Theory of scattered fracture at the complex stress state 189 8.1 Some variants of the volume fracture theory and their connection with the theory of plasticity 189 Historic information 189 The theory of long-term strength considering damage accumulation 195 8.2 A proposed variant of the phenomenological theory of fatigue and fracture 200 Basic hypotheses 200 Sphere function approximations by three-dimensional tensors 202 Dependence of sphere functions on the stress tensor 209 Local failure conditions 210 8.3 Strength at the complex stress state 211 Application of the failure criterion max D, = I 211 Failure analysis under complex loading 216 Examples of long-term strength calculations by using the failure criterion I,D, ds = 1 219 8.4 Calculating elasticity constants of damaged materials 227 A general scheme for calculating changes in mechanical properties of a damaged material 227 Calculating the elastic properties of a damaged material containing defects in the form of penny-shaped cracks 230 x Contents 8.5 Relating the proposed theory to other strength theories 237 The Afanasyev's theory 237 The Hsiao's theory 241 8.6 Development of the fracture theory of anisotropic media 243 Spherical invariants of an anisotropic medium 243 Specific cases of anisotropic media 247 Applications of the criterion max Dz = I to anisotropic media 250 9 Fracture of polymer and composite materials during high speed tension 254 9.1 Problems and testing techniques 255 Statement of the problem 255 Static test techniques of uniaxial tension and specimen shapes 256 High-speed testing techniques of one-dimensional tension . 257 9.2 Comparison of long-and short-term strength of fiberglass reinforced plastics 260 9.3 Fracture of oriented materials during tension 263 Experimental results and statement of the problem 263 Calculation model of fracture to oriented polymers 266 10 Analysis of the temperature field during vibrational loading with consideration given to scattered damage 279 10.1 Statement of the problem 279 10.2 Solution for a specimen with uniform temperature distribution 282 10.3 Solutions to an infinite cylinder with convection on the lateral surface 285 References 293 Index 311 XI
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