ISO INTERNATIONAL STANDARD 20501 Second edition 2019-03 Fine ceramics (advanced ceramics, advanced technical ceramics) - Weibull statistics for strength data Céramiques techniques - Analyse statistique de Weibull des données de reésistance a la rupture Reference number IS0 20501:2019(E) ISO @ IS0 2019 IS0 20501:2019(E) COPYRIGHTPROTECTEDDOCUMENT @ ISO 2019 All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior written permission. Permission can be requested from either IsO at the address below or Iso's member body in the country of the requester. ISO copyright office CP 401 : Ch. de Blandonnet 8 CH-1214 Vernier, Geneva Phone: +4122 749 0111 Fax: +41 22 749 09 47 Email: [email protected] Website: www.iso.org Published in Switzerland ii @ IS0 2019 - All rights reserved IS0 20501:2019(E) Contents Page Foreword ..iv Introduction. ..V 1 Scope. .1 2 Normative references ..1 3 Terms and definitions 3.1 Defect populations. .1 3.2 Mechanical testing. ..3 3.3 Statistical terms .3 3.4 Weibull distributions. 4 4 Symbols ..5 5 Significance and use ..6 6 Method A: maximum likelihood parameter estimators for single flaw populations ..7 6.1 General .7 6.2 Censored data .8 6.3 Likelihood functions. .8 6.4 Bias correction ..8 6.5 Confidenceintervals 10 7 Method B: maximum likelihood parameter estimators for competing flaw populations...13 7.1 General 13 7.2 Censored data ..14 7.3 Likelihood functions. .14 8 Procedure .15 8.1 Outlying observations .15 8.2 Fractography .15 8.3 Graphical representation .16 9 Test report ..18 Annex A (informative) Converting to material-specific strength distribution parameters ..19 Annex B (informative) Illustrative examples .21 Annex C (informative) Test specimens with unidentified fracture origin .28 Annex D (informative) Fortran program ..31 Bibliography .36 @ IS0 2019 - All rights reserved iii