James G. Conley

Effect of lattice disregistry variation on the late stage phase transformation behavior of precipitates in NiAlMo alloys

Abstract A variety of experimental techniques have been applied to examine how compositional variations in lattice disregistry (δ) affect the coarsening kinetics and particle morphology evolution of γ′ particles in several Ni-Al-Mo alloys. Mo segregates to and increases the lattice parameter of the γ matrix in two phase Ni-base Al alloys. Therefore, controlled ternary additions of Mo to dilute, binary Ni-Al alloys permits variation of the lattice parameter disregistry between the Ni-base solid solution and the Ni3Al ordered precipitates. Compositions were selected to maintain an approximately constant 10% volume fraction of the second phase. The coarsening rate of the γ′ phase is observed to decrease with decreasing lattice disregistry and decreasing Al Mo ratio. The implications of this observation are discussed with reference to differences in solid solubility, diffusivity and interfacial energy. The γ′ particle shape in low coherency strain alloys is observed to be spherical and independent of particle size. In an alloy exhibiting appreciable δ and coherency strain, the γ′ particles evolve from randomly distributed spheres to sharply aligned cubes and rods as particle size increases. There is also an increase in δ with aging time in this alloy. Compression creep of [100] single crystals at 750°C did not affect the shape of particles in the low coherency strain alloys while in a higher disregistry alloy, a highly oriented array of plates grew with long edges perpendicular to the applied stress direction. These findings are discussed with regard to stress and thermodynamic considerations.

Rapid prototyping and solid free form fabrication

This article will give a brief review of the start-of-the-art in commercial practice and advanced research in the field of Rapid Prototyping with special attention to the additive methods of Solid Free Form Fabrication. Recent applications of this technology in computer integrated manufacturing environments will be outlined. Future applications and research in new materials will also be addressed.

The effect of microscopic inclusion locations and silicon segregation on fatigue lifetimes of aluminum alloy A356 castings

Abstract The microstructural heterogeneity of aluminum alloy A356 permanent mold castings impacts fatigue performance differently depending on location in the casting. Casting conditions, which include casting temperature, gradients in the mold temperature, plunger speed and casting pressure are variables which can affect solidification rates and therefore, the microstructure within the casting. In this paper an experimental investigation of fatigue performance of specimens cut from various locations in a test bar of cast aluminum alloy A356 is reported. The number of cycles to failure for each test was recorded and the fracture surfaces and local microstructure examined. It was observed that local fatigue resistance varied substantially along the solidification path while tensile strength was little affected. The amount of Al–Si eutectic and the density of micropores increases along the solidification path. Samples located near the surface and the farthest from the gate end demonstrated the longest lifetimes. Conversely, the samples taken from the centerline of the casting closest to the gate end demonstrated the shortest lifetimes.

Modeling the effects of cooling rate, hydrogen content, grain refiner and modifier on microporosity formation in Al A356 alloys

Cast Aluminum-Silicon alloys are used in numerous automotive and industrial weight sensitive applications because of their low density and excellent castability. The presence of trapped gas and or shrinkage pores in certain locations within castings has been shown to influence fatigue life. These micromechanical defects can be found most anywhere in a casting depending on processing conditions. A large amount of porosity located in the center of the cast material thickness may have no effect on mechanical properties or fatigue performance. A smaller, isolated pore near a surface may have a significant impact on mechanical properties. Hence, it is important to develop a comprehensive model to predict the size, location and distribution of microporosity in castings. In this work, we model the effect of various casting process parameters on microporosity formation for aluminum A356 alloy castings. The process parameters include cooling rate, hydrogen content, grain refiner and modifier. The proposed two-dimensional model predicts the size, morphology and distribution of microporosity at a given location in the casting. The method couples a mathematical model of porosity evolution with a probabilistic grain structure prediction model. The porosity evolution model is based on the simultaneous solution of the continuity and momentum equations for the metal and the mass conservation equation for the dissolved gas. The nucleation and growth of grains are simulated with a probabilistic method that uses the information from a heat transfer simulation, i.e. temperature and solid fraction, to determine the transition rules for grain evolution. The simulation results correlate well with experimental observation of porosity in cast structures.

A simulation-based design paradigm for complex cast components

This paper describes and exercises a new design paradigm for cast components. The methodology integrates foundry process simulation, non-destructive evaluation (NDE), stress analysis and damage tolerance simulations into the design process. Foundry process simulation is used to predict an array of porosity-related anomalies. The probability of detection of these anomalies is investigated with a radiographic inspection simulation tool (XRSIM). The likelihood that the predicted array of anomalies will lead to a failure is determined by a fatigue crack growth simulation based on the extended finite element method and therefore does not require meshing nor remeshing as the cracks grow. With this approach, the casting modeling provides initial anomaly information, the stress analysis provides a value for the critical size of an anomaly and the NDE assessment provides a detectability measure. The combination of these tools allows for accept/reject criteria to be determined at the early design stage and enables damage tolerant design philosophies. The methodology is applied to the design of a cast monolithic door used on the Boeing 757 aircraft.

Value Articulation: A Framework for the Strategic Management of Intellectual Property

This article introduces a framework that helps to assimilate intellectual property management activities with the practices of marketing and strategy. With the framework, the management of IP rights is explained within marketing constructs such as the unique selling proposition. The article presents case studies that explore the applicability of the framework in a diversity of industry contexts and firm sizes.

Towards intelligent setting of process parameters for layered manufacturing

The performance of a layered manufacturing (LM) process is determined by the appropriate setting of process parameters. The study of the relationship between performance and process parameters is therefore an important area of LM process planning research. The trend in modern industry is to move from conventional automation to intelligent automation. LM technology is essentially an automated manufacturing technology that is evolving towards an intelligent automation technology. Slicing solid manufacturing (SSM) is a LM technique using paper as the working material and a CO2 laser as the cutting tool. In this manuscript, a back propagation (BP) learning algorithm of an artificial neural network (ANN) is used to determine appropriate process parameters for the SSM method. Key process parameters affecting accuracy are investigated. Quantitative relationships between the input parameters and output accuracy are established by developing the BP neural network.

The ryobi “air-clean” 4-cycle engine: A case study in engineering and manufacturing management

AbstractA number of TQM processes were employed during the rapid development of the revolutionary “Air Clean” (AC), four cycle engine recently introduced by the Ryobi Group of companies. A dynamic, cross functional team organization was used to involve all functions. A simple form of quality function deployment was used to identify desirable product design, safety and service features. The challenges presented by the QFD data were combined with identified design for assembly and design for manufacturing concerns to create the project schedule together with a flow plan for concurrent engineering. Statistical process control of critical machined dimensions was introduced to avoid tolerance stack-up and performance variability. The actual performance of the team verses planned scheduling targets will be compared. Team dynamics and midterm organizational changes required to satisfy design, cost and performance objectives will be reviewed. Important planning mnemonics and graphics used to educate team members ...

AstraZeneca, Prilosec, and Nexium: Marketing Challenges in the Launch of a Second-Generation Drug

Tom McKillop, CEO of AstraZeneca, faced the classic quandary of large pharmaceutical firms. The firms patent for Prilosec (active ingredient omeprazole) was expiring. Severe cost-based competition from generic drug manufacturers was inevitable. Patent expirations were nothing new for the US

3M ESPE AG: Managing Intellectual Property in the Dental Impression Materials Market

15.8 billion in revenues drug firm, but Prilosec was the firms most successful drug franchise, with global sales of US