Low Cycle Fatigue of Composite Materials in Army Structural Applications: A Review of Literature and Recommendations for Research

摘要

Low cycle fatigue (LCF) of laminate composite structures used in Army applications is assessed to identify the key physical phenomena occurring during LCF processes and to determine their main characteristics. Special attention is given to the LCF conditions inherent in Army structures (i.e., high cyclic or pulse loads reaching up to 90% of the ultimate strength in a fraction of a second). A summary of fatigue-related issues in laminate composites employed in Army land combat systems is presented. Analysis indicates that finite strain rate effects are important under LCF conditions and the pulse vibration fatigue (PVF). Fatigue damage mechanisms, evolution patterns of damage, and damage accumulation processes are singled out and thoroughly analyzed as the key mechanical phenomena contributing to the changes in the material damage state and the property degradation under fatigue conditions. Possible correlation between ballistic and LCF performance is discussed. Various models for damage accumulation and fatigue life predictions are reviewed. Recommendations for fundamental research in the areas relevant to the LCF of composite structures are included to establish a conceptual framework for the U.S. Army Research Laboratory (ARL) LCF Program.