Rudland D.,U.S. Nuclear Regulatory Commission |
Csontos A.,U.S. Nuclear Regulatory Commission |
Shim D.-J.,Engineering Mechanics Corporation Of Columbus
Journal of Pressure Vessel Technology, Transactions of the ASME | Year: 2010
Typical ASME Section XI subcritical cracking analyses assume an idealized flaw shape driven by stress intensity factors developed for semi-elliptical shaped flaws. Recent advanced finite element analyses (AFEA) conducted by both the United States Nuclear Regulatory Commission (U.S.NRC) and the nuclear industry for long circumferential indications found in the pressurizer nozzle dissimilar metal welds at the Wolf Creek power plant suggest that the semi-elliptical flaw assumption may be overly conservative in some cases. The AFEA methodology that was developed allowed the progression of a planar flaw subjected to typical stress corrosion cracking (SCC)-type growth laws by calculating stress intensity factors at every nodal point along the crack front, and incrementally advancing the crack front in a more natural manner. Typically, crack growthanalyses increment the semi-elliptical flaw by considering only the stress intensity factor at the deepest and surface locations along the crack front, while keeping the flaw shape semi-elliptical. In this paper, a brief background to the AFEA methodology and the analyses conducted in the Wolf Creek effort will be discussed. In addition, the predicted behavior of surface cracks under normal operating conditions (plus welding residual stress) using AFEA will be investigated and compared with the semi-elliptical assumption. Conclusions on the observation of when semi-elliptical flaw assumptions are appropriate will be made. These observations will add insight into the conservatism of using an idealized flaw shape assumption. Copyright © 2009 by ASME. Source
Agency: Department of Transportation | Branch: | Program: SBIR | Phase: Phase I | Award Amount: 100.00K | Year: 2008
Emc2's proposal provided to DOT in response to SBIR Research topic 07-PH1 on "Design Optimization for Soft Crack Arrestors" focuses on the development of key material property data needed to design "soft crack arrestors". This testing will be done over a range of temperatures to cover extreme conditions for future pipeline designs. It is also essential to develop this data at the loading rates that arrestor will experience during a crack arrest event. With the material property data, the Emc2 crack arrestor design criterion will be used to design arrestors for subsequent full-scale validation tests in a Phase II effort. Emc2 also has the only high-energy full-scale burst test facility in North America for conducting large-diameter pipe fracture and crack arrestor experiments. The Emc2 staff has been involved in conducting high-rate laboratory testing, as well as full-scale pipe crack arrestor testing in a series of proprietary research programs for various pipeline companies. In prior testing, the Emc2 staff also developed and published a design criterion for crack arrestors based on strength considerations, whereas the new Emc2 patent for soft crack arrest covers ductility requirements as well.
Agency: National Science Foundation | Branch: | Program: SBIR | Phase: Phase II | Award Amount: 478.54K | Year: 2002
This Small Business Innovation Research (SBIR) Phase II project will develop and commercialize the Magnetic Pulse Welding (MPW) system, a novel materials joining process. The goal is to establish MPW as a reliable and economic method to weld tubular structures. The project will conduct research and engineering that will address the critical technical hurdles for the commercial implementation and dissemination of the new welding technology. The commercial applications would revolutionize the assembly process of the hydroformed tubular structures in automotive chassis and space frame applications. This process will promote the hybrid automotive body structure design that uses tubes of both aluminums and steels and will enable joining of different materials such as titanium to superalloys for aerospace and electronic applications.
Agency: Environmental Protection Agency | Branch: | Program: SBIR | Phase: Phase I | Award Amount: 70.00K | Year: 2003
Engineering Mechanics Corporation of Columbus¿ (Emc2) approach is to convert both municipal and industrial solid waste products into large dimensional composite timbers for structural and waterfront applications through a novel and efficient manufacturing process. The environmental benefits include: (1) diversion of solid waste plastics and reinforcements from landfills; (2) pollution prevention as a substitute for copper-, chromium-, and arsenic-treated timbers; and (3) conservation of natural resources and rainforests. This feasibility study will investigate methods for joining structural-grade recycled plastic lumber (SG-RPL) that will result in a high production rate for laminated recycled composite timbers (RCTs). The specific target markets for RCTs are marine and waterfront structural components such as fender piling, bearing piles, and other large dimensional components. This market is estimated to be in excess of $40 billion, and the need for alternate, durable, and environmentally friendly materials with long service life is particularly acute due to premature failure of traditional material systems. A novel, patentable formulation with postindustrial and postconsumer waste stream already has been developed by the Principal Investigator along with a private-sector client for manufacturing smaller dimension, cost-competitive, high-performance SG-RPL. A pilot plant for this product also has been installed. Emc2¿s approach is to demonstrate that the use of plastics welding technology to convert the SG-RPL from existing production to large dimensional RCTs at extremely high production rates is technically feasible and commercially viable. Thus, a commercialization partner for the technology to be developed during Phases I and II already has been identified and will work cooperatively from project inception to the marketing of end products. The anticipated results from Phase I are to prove the feasibility of the appropriate welding technology that results in a high-performance RCT as well as its scalabilitv for commercial manufacture. During Phase II, prototype equipment will be fabricated for manufacturing RCTs from SG-RPL, and field trials in a variety of applications will be conducted.
Agency: Department of Defense | Branch: Army | Program: SBIR | Phase: Phase I | Award Amount: 70.00K | Year: 2005
The proposed Phase I feasibility study examines the possibility of developing a full-mobile extrusion plant capable of manufacturing structural thermoplastic composite lumber (TCL) and plastic piping. Novel concepts to enable the modification of existing equipment into a manufacturing system on skids have been proposed. The intent of such a system is to enable the manufacture of TCL construction materials in exact sizes and quantities as the need arises, on-site using local battlefield debris materials as feedstock as appropriate. Each component of traditional manufacturing system for piping and TCL will be modified using innovative ideas to make it fully-portable and quick assembly for on-site manufacture.