Residual Stress in Automotive Powertrains: Methods and Analyses

Abstract

Residual stress is one of the main reasons for failure of automotive cylinder blocks and engine heads. These failures are typically associated with in-service distortion or cracking occurring in engines during operation cycles. The problem becomes more pronounced for engines that are running at elevated operating pressures and temperatures, limiting R&D options in developing and implementing higher-efficiency engines. New aluminum alloys and manufacturing methods have been introduced with varying degree of success, in many cases affected by the stress magnitudes and stress distribution in the component. Therefore, active research is ongoing internationally on finding the most reliable methods of stress analysis as a basis for developing efficient methods for stress mitigation. The current study presents a comparison between two experimental strain measurements techniques: a destructive method that is based on application of strain gauge sensors, and a non-destructive method using neutron diffraction. The results indicate that although the strain gauge method provides an indication of the nature (i.e. compression or tension) of strain within a component, this method should primarily be used for surface measurements and qualitative analyses only. Neutron diffraction remains the superior technique for strain analysis, particularly for engineering components with complex geometries. The results from this study provide the transportation industry with a more comprehensive understanding of the efficacy of utilizing strain gauge sensors, neutron diffraction or finite element modelling for measuring the residual strain in cast components. The results will help manufacturers to develop the next generation of powertrain systems with increased efficiency and improved performance.

Advancements in Monitoring of Tribological Stress in Bearings Using Thin-Film Strain Gauges

“…In most cases, important measured variables such as strain and temperature are measured with the help of resistive sensors. Metallic strain gauges are used in the automotive industry to measure strain as well as pressure condition of castings and engine blocks [1]. In the energy sector, temperature and strain sensors are used to quantitatively evaluate the structural performance of buried pipelines considering longitudinal bending loads and axial thermal stresses [2].…”

Degeneration Effects of Thin-Film Sensors after Critical Load Conditions of Machine Components

“…Important measurement variables are strain and temperature, which are usually measured using resistive sensors. In the automotive sector, for example, metallic strain gauges are used to measure the strain and compression condition of cast parts and engine blocks [1]. In the energy sector, strain gauges are used in 3D-woven composite spar caps for structural health monitoring (SHM) of wind-turbine blades and a reduction in measurement costs [2].…”