_STP_490-1972.pdf

EFFECT OF NOTCHES ON LOW-CYCLE FATIGUE A Literature Survey Prepared for the METALS PROPERTIES COUNCIL by B.M.Wundt ASTM SPECIAL TECHNICAL PUBLICATION 490 List price$3.00 04-490000-30 AMERICAN SOCIETY FOR TESTING AND MATERIALS 1916 Race Street,Philadelphia,Pa.19103 Copyright by ASTM Intl(all rights reserved);Mon Dec 21 11:06:02 EST 2015Downloaded/printed byUniversity of Washington(University of Washington)pursuant to License Agreement.No further reproductions authorized.?9 BY AMERICAN SOCIETY FOR TESTING AND MATERIALS 1972 Library of Congress Catalog Number:75-152133 NOTE The Society is not responsible,as a body,for the statements and opinions advanced in this publication.Printed in Alpha,N.J.May 1972 Copyright by ASTM Intl(all rights reserved);Mon Dec 21 11:06:02 EST 2015Downloaded/printed byUniversity of Washington(University of Washington)pursuant to License Agreement.No further reproductions authorized.TABLE OF CONTENTS SECTION SECTION SECTION C.SECTION D.SECTION E.SECTION F.SECTION G.SECTION H.SECTION I.SECTION J.SECTION K.A.INTRODUCTION AND SUMMARY.B.NOMENCLATURE.CYCLIC STRESS-STRAIN DIAGRAM Discused Ref.3,4,11,24,30 Other Ref.33,45,56 NEUBERS RELATIONSHIP BETWEEN STRESS AND STRAIN CONCENTRATION FACTORS AND APPLICATION TO LOW-CYCLE FATIGUE.Discussed Ref.38,39,49,54 Other Ref.7,30 STOWELL-HARDRATH-OHMAN EQUATION AND ITS APPLICATION TO LOW-CYCLE FATIGUE.Discussed Ref.4,6,7,8,12,14,16,33,44,46,56,57 Other Ref.3,6,20,21,22,23,35,40,42 FATIGUE STRENGTH-REDUCTION FACTORS ON STRAIN BASIS.Discussed Ref.19,23,26,27,28,29,45 FATIGUE STRENGTH REDUCTION Discussed Ref.2,20,37,53 Other Ref.52 11 15 29 FACTORS ON STRESS BASIS.45 FATIGUE STRENGTH REDUCTION FACTORS IN BENDING.53 Discussed Ref.1,5,17 MISCELLANEOUS STUDIES ON EFFECT OF NOTCHES IN LOW-CYCLE FATIGUE.Discussed Ref.9,26,40,41,42 PROPOSED FUTURE WORK.Discussed ReL 31 REFERENCES.61 65 67 iii Copyright by ASTM Intl(all rights reserved);Mon Dec 21 11:06:02 EST 2015Downloaded/printed byUniversity of Washington(University of Washington)pursuant to License Agreement.No further reproductions authorized.SECTION A.INTRODUCTION AND SUMMARY STP490-EB/May 1972 A.1.-This literature review was prepared for Subcommittee 3 of the Metal Properties Council.At present there are not available comprehensive re-views of literature pertaining to the effect of notches and discontinuities on life in low-cycle fatigue.Note that in Section 1 of R.55 there are listed reviews and annotations pertaining to low-cycle fatigue,some of which touched upon the above subject.A.2.-This review consists of eleven sections,A to K.It contains selected figures from papers reviewed.The Sections are listed in the Table of Contents.Note that the discussed references are listed in each Section.A.3.-Practically all of the 59 references listed in Section K were taken from Section 4 of R.55,which was prepared by the reviewer for the Metal Properties Council.All papers reviewed were published between 1955 and early 1969,either in the United States or in the United Kingdom,except for one published in Japan and two in Germany.In some instances the prepared reviews were more comprehensive than in others,depending on the content and the clarity of the paper.Also,in most cases a number of the original figures were reproduced.A.4.-The reviewer has found it advisable to de-velop a consistent nomenclature of his own and to use it throughout the literature survey.For details of nomenclature and abbreviations used,see Section B.A.5.-The cyclic stress-strain diagrams which lately have assumed considerable importance in low-cycle fatigue analysis are discussed in a separate Section C.The total imposed strain range in the apex of a notch is of particular importance in cyclic life of notched specimens.Its approximate determination,as proposed in a number of references,is discussed in Section D(Neubers relation)and in Section E(Stowell-Hardrath-Ohman equation).A.6.-The experimental fatigue strength reduction factor kf which is the ratio of endurance strength of an unnotched specimen to the nominal endurance strength of a specimen with a notch,is well known.However,when an attempt is made to extend the con-cept to a limited cyclic life rather than to fatigue en-durance,complications arise because depending on the particular test procedure used,a number of definitions are possible.The main reason for it is the non-linear relationship between the imposed stress range and the resulting strain range in the low-cycle fatigue region.As a rule,in tension-compression or zero-tension low-cycle fatigue tests,notched specimens are controlled by a nominal stress range,referred to the net section.On the other hand,cycling loading of unnotched speci-mens may be controlled either by a stress range or by a strain range.The fatigue strength reduction factor FS-thRF is larger than one and is usually defined as the ratio of the controlling stress or strain range for the unnotched specimen to the respective,controlling stress or strain range fo