Overview of Composite Airframe Life Extension Program Project 2: Tools For Assessing The Durability And Damage Tolerance Of Fastened Composite Joints

摘要

The CALE Project 2 was devised to develop and assess two types of DADT analysis tools for composite bolted joints in anticipation of potential service life extension of modern tactical aircrafts with primary composite airframe structures. Led by Northrop Grumman Corporation (NGC), the two groups of tools-i.e., simple "parametric" approach for durability analysis and detailed PDA methods for damage tolerance assessment of assemblies-were developed during the 14-months program through three parallel tasks. Under Task 1, NGC developed a set of tools for quick assessment of durability-i.e., hole elongation-in multi-bolt joints. Under Task 2, the three PDA developers from University of Washington, Vanderbilt University, and Global Engineering and Materials, Inc. improved their existing methods and models for assessing damage tolerance which concerns damage growth and residual strength of critical joints that would be identified through the durability tools. Finally, in Task 3, both tools were enhanced through numerous prediction and calibration iterations using 184 coupon-level data encompassing OHT/FHT, OHC/FHC, SSB, and tension BB configurations. The PDA tools were then further assessed under Task 3 by conducting blind predictions of static and fatigue tests on 10-bolt composite-metallic joints in tension and compression.