Search Results

The reliability of engine valve springs is a very important issue from the point of view of warranty. This paper presents a combined experimental and statistical analysis for predicting the fatigue limit of high tensile engine valve spring material in the presence of non-metallic inclusions. Experimentally, Fatigue tests will be performed on valve springs of high strength material at different stress amplitudes. A model developed by Murakami and Endo, which is based on the fracture mechanics approach, Extreme value statistics (GUMBEL Distribution) and Weibull Distribution will be utilized for predicting the fatigue limit and the maximum inclusion size from field failures. The two approaches, experimental and theoretical, will assist in developing the S-N curve for high tensile valve spring material in the presence of non-metallic inclusions.

Control of annoying noises such as buzzes, squeaks and rattles (BSRs) is particularly important for complex products such as automobiles. This importance has become even more significant as electric vehicles become more popular, eliminating much of the ambient background vehicle noise. A customer's perception of the durability and solidness of a vehicle is based largely on sensory responses such as sound. Recent advances in beamforming technology have the potential to change the way BSR audits and vehicle development testing are done. This paper introduces the application of spherical beamforming technology to BSR testing and provides test results showing the localization accuracy of a rigid spherical array system in a vehicle cabin.

To stay competitive, new products require faster development time at low cost and good quality. Defense as well as commercial industries are forced to use analytical tools to stay competitive in a tough market. The use of simulation tools and approximation techniques in evaluating product performance during the early stages of the product development has a major impart on the product development efficiency, effectiveness, and lead time. Building physical prototypes of complex systems is expensive and it is difficult and time consuming to develop them. It is extremely beneficial to know as much as possible about the product performance and to optimize its dynamic characteristics before the first physical prototype is built.

The experimental methods focused on utilizing the newly developed NOVA induction heating and hardening manufacturing process as an adapted method to produce high performance engine valve springs. A detailed testing plan was used to evaluate the expected and theorized possibility for fatigue life enhancement. An industry standard statistical analysis method and tools were employed to objectively substantiate the findings. Fatigue cycle testing using NOVA induction-hardened racing valve springs made of ultra-high tensile material were compared to data for springs with traditional heat treatment and those with standard processing. The results were displayed using Wöhler and modified Haigh fatigue life diagrams. The final analysis suggests that NOVA processed springs have a seemingly slight, yet significant benefit in fatigue life of 5 - 7% over springs processed through a competing method.

In this study, a new nonlinear correlation between Brinell hardness and ultimate tensile strength is proposed. The correlation factor in this case is higher than that found in the current literature. The ultimate tensile strength is replaced by an equivalent hardness expression in the Modified Universal Slopes Method. This change results in fatigue parameters that are predicted using hardness, true fracture ductility, and modulus of elasticity. This new fatigue life prediction approach is compared with the original Modified Universal Slopes method and experimental data in literature. This method is valid for steel with hardness that ranges from 150HB to 660HB. The results show that this method provides better approximations of the strain-life curves when compared with the Modified Universal Slopes and experimental data.