Review of Non-destructive Testing (NDT) Techniques and their applicability to thick walled composites

A tier 1 automotive supplier has developed a novel and unique kinetic energy recovery storage system for both retro-fitting and OEM application for public transport systems where periodic stop start behaviour is paramount. A major component of the system is a composite flywheel spinning at up to 36,000 rpm (600 Hz). Material soundness is an essential requirement of the flywheel to ensure failure does not occur. The component is particularly thick for a composite being up to 30 mm cross section in some places. The geometry, scale and material make-up pose some challenges for conventional NDT systems. Damage can arise in composite materials during material processing, fabrication of the component or in-service activities among which delamination, cracks and porosity are the most common defects. A number of non-destructive testing (NDT) techniques are effective in testing components for defects without damaging the component. NDT techniques like Ultrasonic Testing, X-Ray, Radiography, Thermography, Eddy current and Acoustic Emission are current techniques for various testing applications. Each of these techniques uses different principles to look into the material for defects. However, the geometry, physical and material properties of the component being tested are important factors in the applicability of a technique. This paper reviews these NDT techniques and compares them in terms of characteristics and applicability to composite parts

Assessment of mechanical properties and microstructure characterizing techniques in their ability to quantify amount of cold work in 316l alloy

Stress corrosion cracking (SCC) behavior is a matter of concern for structural materials, namely, stainless steels and nickel alloys, in nuclear power plants. High levels of cold work (CW) have shown to both reduce crack initiation times and increase crack growth rates. Cold working has numerous effects on a material, including changes in microstructure, mechanical properties, and residual stress state, yet it is typically reported as a simple percent change in geometry. There is need to develop a strategy for quantitative assessment of cold-work level in order to better understand stress corrosion cracking test data. Five assessment techniques, commonly performed alongside stress corrosion cracking testing (optical microscopy (OM), electron backscatter diffraction (EBSD), X-ray diffraction (XRD), tensile testing, and hardness testing) are evaluated with respect to their ability to quantify the level of CW in a component. The test material is stainless steel 316L that has been cold-rolled to three conditions: 0%, 20%, and 30% CW. Measurement results for each assessment method include correlation with CW condition and repeatability data. Measured values showed significant spatial variation, illustrating that CW level is not uniform throughout a component. Mechanical properties (tensile testing, hardness) were found to correlate most linearly with the amount of imparted CW

Investigations on electromagnetic noises and interactions in electronic architectures : a tutorial case on a mobile system

Electromagnetic interactions become critic in embedded and smart electronic structures. The increase of electronic performances confined in a finite volume or support for mobile applications defines new electromagnetic environment and compatibility configurations (EMC). With canonical demonstrators developed for tutorials and EMC experiences, this paper present basic principles and experimental techniques to investigate and control these severe interferences. Some issues are reviewed to present actual and future scientific challenges for EMC at electronic circuit level

Online and Offline BIST in IP-Core Design

This article presents an online and offline built-in self-test architecture implemented as an SRAM intellectual-property core for telecommunication applications. The architecture combines fault-latency reduction, code-based fault detection, and architecture-based fault avoidance to meet reliability constraint

Exposing errors related to weak memory in GPU applications

© 2016 ACM.We present the systematic design of a testing environment that uses stressing and fuzzing to reveal errors in GPU applications that arise due to weak memory effects. We evaluate our approach on seven GPUS spanning three NVIDIA architectures, across ten CUDA applications that use fine-grained concurrency. Our results show that applications that rarely or never exhibit errors related to weak memory when executed natively can readily exhibit these errors when executed in our testing environment. Our testing environment also provides a means to help identify the root causes of such errors, and automatically suggests how to insert fences that harden an application against weak memory bugs. To understand the cost of GPU fences, we benchmark applications with fences provided by the hardening strategy as well as a more conservative, sound fencing strategy

Computer methods for the reduction, correlation and analysis of space battery test data, phase 2, part 1 Final report, 1 Nov. - 31 Dec. 1967

Computer methods for reduction, correlation, and analysis of space battery test dat