Gears are commonly used in transmission systems to adjust velocity and torque. An integral gear or an interference fit could be used in a gearbox. Integral gears are mostly preferred as driving gear for a compact design to reduce the weight of the system. Interference fit makes the replacement of damaged gear possible and re-use of the shaft compared to the integral shaft. However, internal pressure occurs between mating surfaces of the components mated. This internal pressure affects the stress distribution at the root and bottom land of the gear. In this case, gear parameters should be re-considered to assure gear life while reducing the size of the gear. In this study, interference fitted gear-shaft assembly was examined numerically. The effects of rim thickness, profile shifting, module and fit tolerance on bending stress occurring at the root of the gear were investigated to optimize gear design parameters. Finite element models were in good agreement with analytical solutions. Results showed that the rim thickness of the gear is the main parameter in terms of tangential stress occurring at the bottom land of the gear. Positive profile shifting reduces the tangential stress while the pitch diameter of the gear remains constant. Also, lower tolerance class could be selected to moderate stress for small rim thickness.

Estimating bore profile is important to select an appropriate tool for precision manufacturing in the process planning stage. Also, it helps in reducing the rejection rate of the process. A manufacturer might not be well-equipped and want to make their best with the resource on hand. Three-jaw chuck allows machining a wide range of workpiece, mostly circular parts in a lathe. However, clamping via a three-jaw chuck distorts the workpiece. In this study, the deformation of the bore profile was investigated numerically for circular parts. Finite element analyses were performed to examine dimensional variation for various materials and different wall thicknesses under fully elastic plane stress conditions. The stressed workpiece had a triangular form. Results showed that wall thickness and materials are important parameters on the triangulation of bore diameter. A simple calculation method based on thick-walled vessel theory was proposed to estimate the tolerance grade of the workpiece. This simple method provides the opportunity to reduce the rejection rate in the mass production of circular parts.

This study examines surface roughness measurements via piezo acoustic disks and appropriate signal processing. Surface roughness is one characteristic of surface texture that can have various irregularities inherent to manufacturing methods. The surface roughness parameters and corresponding surface profiles are acquired by a stylus profilometer. Simultaneously, elastic waves propagated along metal surfaces caused by the friction of a diamond tip are obtained in the form of raw sound via piezo acoustic disks. Frequency spectrum analysis showed apparent correlations between the traditionally obtained measurement parameters and the piezo acoustic measurement data. Thus, it is concluded that acoustic friction measurement shows promising results as a novel measurement method for the surface roughness states of certain materials.

Welded joints are frequently used in machine construction, ships, and bridges and must function safely throughout their service life as determined for certain circumstances defined in design codes, standards, and guidelines. Although complex analysis of welded joints gives satisfactory results, factors that modify the endurance limit are common in industrial use. The endurance limit-modifying factors given in reference books are unable to generalize to all types of welded joints. Furthermore, cracks in fillet welded T-joints are likely to start from the toe of the weld bead; however, the weld throat thickness is considered in the calculation of the strength of a welded joint. In this study, we examined the stress concentrations of load-carrying welded T-joints considering bead shape and thickness via finite element analysis and verified the model experimentally. We utilized an electromechanical cylinder to carry out experiments to obtain stresses near the weld bead via strain gauges. The submodeling technique was implemented to obtain results in the regions of stress concentrations as accurately as possible. The results of finite element analysis were in good agreement with experimental results. The present study showed that the ratio of weld throat thickness to plate thickness significantly affects the stress concentration factors of load-carrying welded joints. The maximum stress decreased significantly depending on bead shape and thickness. Endurance limit-modifying factors gathered via analyses assuming the weld as a notch and considering plate thickness could be used in the fatigue strength calculations of welded joints.

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