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Surface distress involving pitting, scuffing, frosting, and high friction leads to failure in fuel injector cams. The relationship amongst relative features of these failures is extremely complex. They comprise local plastic straining, cyclic softening/hardening, crack initiation/propagation, impact, skidding, and third body formation. From an industrial application point of view determination of failure probability and service life expectancy are important. Although factors such as operating loads, speeds, number of loading cycles, surface roughness, lubrication conditions, and third body particles are known to affect the life of gears and bearings, the effect of such factors on the life of cam-follower contact is little known. In particular, failure of cams due to pitting under conditions of rolling/sliding friction is unclear.

Since the advent of P/M technology as a near net shape production process, millions of mechanical components of various shapes and sizes have been produced. Although P/M continues to be one of the fast growing shaping processes, it suffers from the inability to produce intricate geometry's such as internal tapers, threads or recesses perpendicular to pressing direction. In such cases application of machining as a secondary forming operation becomes the preferred alternative. However, machining of P/M parts due to their inherent porosity is known to decrease tool life and increase tool chatter and vibration. Consequently, several attempts have been made to improve the machinability of P/M materials by either addition of machinability enhancing elements such as sulfur, calcium, tellurium, selenium, etc., or by resin impregnation of P/M parts.

The plasticity characteristics of the material were used to model the cutting force material, and were verified by using FEM techniques. In addition, the solutions generated by The Merchant's Circle were proven by vector algebra, and a shear angle solution which uses the plasticity characteristics of the material is also presented. A good agreement was found between the mathematical models, FEM results, and experimental data results found in open literature.

During the last decade, several technological advances have taken place in the construction and fabrication industry in terms of methods, processes and tools which ultimately reduce fabrication time and costs. Fastening of metal plates with bolts and nutes in civil construction of large structures has recently been replaced by self drilling-tapping fasteners. The technique of using a self drilling-tapping fastener not only eliminates use of separate drills and drilling processes, but also eliminates the use of bolts and nuts. In addition, the time to join two plates by a self drilling-tapping fastener is significantly shorter than the time required for joining plates by conventional bolting methods. Although self drilling-tapping fasteners have many advantages, it is equally important that they demonstrate consistent performance in field applications.

Molding of hygroscopic thermoplastics has traditionally been a problem because of the ability of these materials to quickly re-absorb moisture. Even dry, “out of the bag” virgin resins can absorb moisture due to indoor humidities. This paper deals with a comprehensive investigation of mechanical properties of moisture-sensitive, hygroscopic thermoplastic materials. Five different materials were subjected to four different processing conditions resulting in 20 different combinations. Each of 19 out of 20 combinations were subjected to three different ASTM standard tests for tension, flexure, and impact properties. All experiments were conducted under strict adherence to the ASTM standards. The main objective of this research was to investigate if the unvented injection molding process could be replaced by the vented injection molding process, without sacrificing the mechanical properties of the materials. All the experimental results were analyzed both graphically and statistically.

The fatigue strength of materials subjected to dynamic loads is routinely determined by using an ASTM standard rotating beam test. The test specimen is prepared very carefully and tested under closely controlled laboratory conditions. The resulting endurance limit is multiplied by the modifying factors to approximate the endurance limit of mechanical or structural components. Among a variety of modifying factors, surface finish is one of the more important ones. The existing data for surface finish modifying factor for steels is limited to a maximum hardness of 33 Rc. For steel components with a hardness of approximately 50 Rc, the existing surface finish modifying factors cannot be applied. The objective of this research is to develop surface finish modifying factor curves for steels with hardness in the range of 50 to 55 Rc.

A pin-on-disk test rig is used to model two body abrasive wear process. The parameters investigated include applied load, system stiffness, surface roughness, sliding speed, and hardness of the test materials. Two-level full factorial design of experiments is used to analyze the effect of these parameters on wear rate, normal force, and friction force. The wear rate is found to be directly proportional to load, system stiffness, sliding speed, and surface roughness. Where as hardness is found to have inverse effect on wear rate. Among the parameters investigated, normal load and hardness have a significant effect on wear rate. Mathematical models for predicting abrasive wear, friction force and normal force are developed. Within the envelope of parameters investigated, the predictor equations are found to approximate the behavior of wear rate, friction force, and normal force with 96%, 98%, and 94% confidence interval, respectively.

Wear characteristics of four bearing materials have been investigated under different sliding conditions. The bearing materials used were CDA 954, CDA 863, CDA 932, and CDA 938. Using a Taber Wear Tester, a cylinder on a flat geometry was used as a tribo contact pair. All bearing materials in the form of a thick cylindrical disk were subjected to combined sliding-rolling motion against a rotating flat disk. The flat disk was either an abrasive disk, or a very soft steel disk, or a hardened steel disk with and without lubrication. Wear was measured as weight loss after several thousand cycles of rotation. Maximum wear of the bearing materials occurred when the counter body was a very soft steel disk. These results together with the wear rate of each bearing material sliding against four different counter bodies are presented. These results are found to be of practical importance in the design and application of journal bearings made of materials used in this investigation.

A systematic study has been carried out to investigate the effect of change in the stiffness of the system incorporating a tribo contact, on the operational characteristics of a friction pair. Using a pin on disk apparatus six different system stiffnesses were introduced. With each system stiffness a steel sample is slide against two counter bodies: a smooth metal surface, and an abrasive surface. Friction force, normal force, and wear rate are measured. Results indicate that system stiffness has significant effect on wear, vibration, and contact forces. An increase in system stiffness is found to increase wear rate. As the wear rate increased, the coefficient of friction was also found to increase. Mathematical models have been developed to predict wear under varying system stiffness. These results are of particular importance in miniature devices involving moving parts.