ISO INTERNATIONAL STANDARD 7257 Second edition 2016-06-01 Aircraft Hydraulic tubing joints and fittings Rotary flexure test Aéronautique - Joints et raccords pour tubes hydrauliques - Essai de flexion rotative Reference number ISO 7257:2016(E) ISO International Organization for Standardization see=ZHEJIANG INST OF STANDARDIZATION C1 5956617 @IS02016 vided by IHS under No reproduction or networking permitted without license from IHS IS0 7257:2016(E) COPYRIGHT PROTECTED DOCUMENT IS0 2016, Published in Switzerland All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form 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 copyrightoffice Ch. de Blandonnet 8 . CP 401 CH-1214 Vernier, Geneva, Switzerland Tel. +41 22 749 01 11 Fax +41 22 749 09 47 copyright@iso.org www.iso.org Licensee-ZHEJIANG INST OF STANDARDIZoISQ6 -All rights reserved Not for Resale, 2016/8/17 06:54:45 networking permited without license from IHS IS0 7257:2016(E) Contents Page Foreword ..iv Introduction. ..V 1 Scope. ..1 2 Requirements 2.1 Flexure test device 1 2.2 Flexure test specimen 1 2.3 Specimen length and deflection requirements 7 2.3.1 Specimenlength 7 2.3.2 Stress determination. 7 2.3.3 Deflection. 7 2.4 Method of classification of fittings according to S/N flexure performance 7 2.5 Method of determining deflection/fatigue strength .7 3 Procedure. .8 3.1 Preparation for test. .8 3.1.1 Instrumentation, strain gauges .8 3.1.2 Rotary flexure test set-up centring ..8 3.1.3 Flexure stress measurement. .9 3.1.4 Flexure deflection measurement. 3.1.5 Operating pressure. 9 3.2 S/N testing 3.3 Deflection/fatigue testing ..10 4 Formula .10 5 Equipment ..10 Bibliography ..12 iii icensee=ZHEJIANG INST OF STANDARDIZATION C1 5956617 vided by IHS under lic se with ISt without license from IHS