Frontiers of Engineering Reports on Leading Edge Engineering From the 1998 NAE Symposium on Frontiers of Engineering (1999) / Chapter Skim
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Simulation in Manufacturing
Simulation in Manufacturing
Pages 63-84
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From page 65... ...
-based design in realistic complex flows. Complex turbomachinary flows, such as those used in current and future military aircraft engines, exhibit unsteady aerodynamics, forced blade response and high-cycle fatigue, complex confluent interacting flows with strong rotation, compressor surge and stall instabilities, and losses and extremely high temperatures in both the combustor and turbine components.
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From page 66... ...
The CFD played a key role in parameter space surveys, providing guidance on optimum injection flow rate and optimum injection frequency as well as placement of injectors. As the above examples show, simulations play an increasingly important role in design methodologies for complex turbomachinary flows, although much fundamental work is still required to improve existing simulation tools.
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From page 67... ...
The effects of swirl are cleverly added by imposing a body force via swirling inflow conditions, resulting in a practical LES tool for studying realistic combustor flows. Finally, for implementation of low-dimensional models in practical flows, methods must be developed to deal with complicated boundary conditions and improve subgrid-scale modeling.
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From page 68... ...
The success of crystal plasticity theory in predicting behavior in metal forming is built on several things: initialization of a mathematical description for a complex microstructure using experimental data, effective use of computational resources, and visualization of results in a manner that reflects experiment. It is argued that such detail offers both improved predictive capability and effective utilization of computing resources.
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From page 69... ...
Because the distribution is rarely a random one, the texture contains preferred orientations and thus imparts directional properties to the polycrystal. The field of materials science provides a wealth of theory for describing the deformation response at the scale of the crystal (Bishop and Hill, 1951; Taylor, 1938)
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From page 70... ...
In this way, deformation of workplaces may be examined with gradients in the field variables accommodated through finite elements and concomitant response at material points within elements achieved through the crystal plasticity descnption. In general, there are two approaches to combining finite elements with crystal plasticity theory.
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From page 71... ...
The deformed shape of the workplace arising from the simulation may differ significantly from that derived using isotropic material properties a situation more in line with industrial practice. Finite elements may also be applied to examine the deformations within a polycrystal.
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From page 72... ...
Automated collection of BKD measurements from samples of aluminum sheet was carried out by using the orientation imaging technique mentioned above. A mesh was formed by using 14,640 eight-node bricks, and a crystal orientation was assigned based on the BKD data.
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From page 73... ...
and the approach outlined herein provides opportunity for leveraging such resources. The challenge lies in continued development of physically motivated, quantitative descriptions of metal behavior.
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From page 74... ...
1994. Application of polycrystal plasticity to sheet forming.
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From page 75... ...
In addition, research challenges and opportunities in digital service technology for the life-cycle support of products and engineering systems in a global enterprise are introduced. INTRODUCTION Today's industries are facing serious structural problems brought about by their rapid development of overseas activities within a globally integrated manufacturing enterprise.
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From page 76... ...
Digital maintenance diagnostics and maintenance tools such as "watchdog"-type information mechatronics with integrated media will improve the effectiveness of maintenance activities (Goncharenko et al., 1997; Lee, 1992, 1995a,b, 1996c; Lee and Kramer, 1993; Shi et al., 1997~. A typical digital service technology-based teleservice engineering system is illustrated in Figure 1.
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From page 77... ...
For example, component degradation occurs whenever corrective maintenance is required, such as a loose belt, a worn brush of a motor, or dust on a photosensor, but the components have not failed. Detailed degradation is associated with a given range of characteristics of the components, or performance of the components, such as detailed degraded states for a car battery indicator and temperature indicator.
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From page 78... ...
Mapping function g uses the weights associated with the active association cells and generates an output response. Function g may be a simple summation if the weights are attached to active association cells, or it may vary during the training and storage process.
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From page 79... ...
The value of the output for a given input can be changed by changing the weights attached to the active association cells. A procedure for entering a function in a watchdog agent is as follows: 1.
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From page 80... ...
A smart glove would enable operators to perform machine maintenance and performance adjustment collaboratively. RESEARCH ISSUES AND OPPORTUNITIES IN DIGITAL SERVICE TECHNOLOGY To achieve the digital service enterprise in today's globalized manufacturing industries, issues and technical challenges need to be addressed.
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From page 81... ...
A study needs to be conducted to classify all tasks into various categories. As a result, the watchdog agent could perform simple on-line and real-time process change detection for tasks requiring immediate response.
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From page 82... ...
Under various conditions, the system should be able to operate and perform basic functions, albeit with deteriorated performance. For example, if the Internet is not available for data transfer and remote diagnosis, local data processing should be executed to conduct essential tasks that are nominally carried at the remote site.
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From page 83... ...
1995a. Machine performance monitoring and proactive maintenance in computer integrated manufacturing: Review and perspective.
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