Defect Tolerance Assessment Research Articles

Microstructure- and plasticity-based fatigue and defect tolerance assessment of age-hardenable Al-Si cast alloys in LCF and HCF regime

Due to their excellent strength-to-weight ratio and near-net-shape manufacturing possibility, precipitation hardening Al-Si cast alloys are promising candidates for cost-efficient lightweight components in the automotive and railway industry. In this work, the microstructure and the fatigue properties of cast AlSi7Mg0.3-T6 (A356-T6) were analyzed, whereby the influence of a variation in solution annealing, hot isostatic pressing (HIP) densification, solidification rates as well as casting processes, i.e., gravity die and sand casting on the fatigue behavior and fatigue damage tolerance was investigated. Sand castings exhibit a decelerated fatigue crack initiation and enhanced LCF damage tolerance compared to die castings.

Defect Tolerance Assessment Method of Fusion Welded Medium and High Strength Al Alloy Joints

Defect Tolerance Assessment Method of Fusion Welded Medium and High Strength Al Alloy Joints

A novel analytical method for defect tolerance assessment

Due to technology downscaling, defect tolerance analysis has become a major concern in the design of digital circuits. In this paper, we present a novel analytical method that calculates the defect tolerance of logic circuits using probabilistic defect propagation. The proposed method is explained in case of single defect model, but can be easily adapted to handle multiple fault scenarios. The approach manages signal dependencies due to reconvergent fanouts, providing accurate results and performing simple operations.

Defect tolerance assessment of a helicopter component subjected to multiaxial load

In this paper a simple but effective methodology for the defect tolerant assessment of a structural component is presented. The methodology is based on the experimental evidences available in literature that at the fatigue limit non-propagating cracks are observed near defects present in the metallic material. The evaluation of the threshold stress intensity range of these short cracks allows to calculate a safety factor with respect to their propagation. The methodology is applied to the tail rotor hub of a helicopter. The complex geometry and load conditions make this component very interesting for the defect tolerance assessment. The application to an engineering problem allows to describe the difficulties that arise in this process and to show the possible solutions that can be adopted.

Defect tolerance assessment of ARIANE 5 structures on the basis of damage mechanics material modelling

Damage mechanics based material models have been applied to establish fracture control procedures for the failure prediction of ARIANE 5 main structural components as the booster cases including welds, the main stage, and the upper stage cryogenic tank. The main goals of the damage mechanics based investigations were the accurate failure prediction, the clarification of dependency of fracture toughness on geometry, the calibration of analytical methods and the interpretation and optimisation of small scale fracture tests for material characterization and quality assurance. The results of these investigations allowed a failure prediction accuracy with analytical tools which is close to 3D numerical simulations. This could be demonstrated both with ductile (Gurson) and brittle (RKR) damage mechanics models.