Constitutive Behavior and Damage Characterization of High Temperature Polymer Composites

Abstract

REPORT DOCUMENTATION PAGEPublic reporting burden for this collection of information is estimated to average 1 hour per response, including the fimerfor reviewinj dS needed and completinq and reviewing this collection of information. Send comments regarding this burden estimate or any ott 4302 Respondents should be aware that notwithstanding any other provfeion of law no person shall be subject to any penalty for f, valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. _ AFRL-SR-BL-TR-01-igthe ucing 02-jrrently REPORT DATE (DD-MM-YYYY) 31-08-2001 REPORT TYPE Final TITLE AND SUBTITLE Constitutive Behavior and Damage Characterization of High Temperature Polymer Composites AUTHOR(S)Isaac M. Daniel, Jyi-Jiin Luo and Zuo Sun PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES)Northwestern University Evanston, EL 60208 DATES COVERED (From -To)Oct. 15.199715. -April 14,2001 5a. CONTRACT NUMBER 5b. GRANT NUMBER F49620-98-1-0056 5c. PROGRAM ELEMENT NUMBER 5d. PROJECT NUMBER 5e. TASK NUMBER 5f. WORK UNIT NUMBER SPONSORING / MONITORING AGENCY NAME(S) AND ADDRESS(ES)Air Force Office of Scientific Research (AFOSR) Arlington, VA 22203-1977 PERFORMING ORGANIZATION REPORT NUMBERC416-4 . t . , , The objective of this investigation was to characterize the constitutive behavior, physical aging, damage mechanisms and damage development in high temperature polymer matrix composites under various environmental and loading conditions. The aging induced volumetric shrinkage was measured and a model was proposed capable of predicting aging under any temperature history. In the case of monotonically loaded laminates a unique and simple general relationship was developed between applied load and crack density independent of lamination geometry and temperature and accounting for statistical variability. Under fatigue conditions a master curve was developed relating damage (crack density) and fatigue cycles, independent of layup and temperature. It is related to and affected by physical aging of the polymeric matrix, viscoelastic deformation (creep) and hygrothermomechanical degradation. It is therefore important to investigate the processes involved and any accelerated test methodologies that will yield valid predictions of long term behavior. SPONSOR/MONITOR'S ACRONYM(S) SPONSOR/MONITOR'S REPORT NUMBER(S) DISTRIBUTION / AVAILABILITY STATEMENT Distribution unlimited SUPPLEMENTARY NOTES ABSTRACTt ,The objective of this investigation is to characterize the constitutive behavior, damage mechanisms and damage development in high temperature polymer matrix composites and develop models for long term behavior under various environmental and loading conditions. The approach followed is as follows:1. Select candidate polymer composite materials. 2.Characterize unidirectional lamina. 3.Perform aging and viscoelastic characterization under isothermal and nonisothermal conditions. 4.Study static and fatigue behavior of laminae and laminates at various cyclic stress amplitudes and temperature levels. 5.Study failure mode...