Expert Details

Expert in Structural Failure Analysis and Design, Including Thermal and Non-Linear Analysis

Expert ID: 722876 Connecticut, USA

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Expert W. Expert has been involved in finding the causes and fixing thermal stress problems since the mid 1970s. These problems have been related to thick walled boiler components, heat exchangers, fluid beds, and fuel cells as well as high temperature piping and tubing failures. These failures involved both steady state and transient conditions and included nonlinear creep and plasticity effects. The failures were related to fatigue, stress-to-rupture or tensile strength. The analysis was performed using classical as well as finite element procedures. NISA, ALGOR, NASTRAN, and MARC have been used. ASME Section VIII div. 2, B31.1, B31.2, B31.3, BS5500 and API 579 criteria have also been applied. The solution to a failure has been design modifications or a change in operating conditions.

As Consulting Engineer at his eponymous firm from 1992 to present, Expert's work includes piping analysis, water wall analysis, non-linear analysis, elastic finite element analysis, reliability analysis, and generator and end ring evaluation.

A specialist in Combustion Engineering from 1974 to 1992, Expert was responsible for fracture mechanics, classical mechanical design, classical buckling problems, finite element analysis, and finite difference analysis.

Expert has solved a number of different types of buckling problems. He used classical mechanics to solve buckling problems in wide flange shapes used as buckstays. (He notes that buckstays are used in boilers to brace the furnace but have different boundary conditions than the same wide flange shape in a building so the buckling rules in the AISC steel code do not apply.) Using classical equations Expert can explain the failures that occurred and produce a safe design. Buckling problems when members were coped were also examined and redesigned as well as buckling of angles in a failed space frame. Nonlinear problems of the buckling of sheet steel used as seals supporting each other in contact was solved using the nonlinear finite element code “MSC-MARC”. In this case it was solved as a static problem and checked to see when the structure became unstable.

Expert has used applied mechanics to solve problems with rotating equipment. Sometimes these problems can be solved using statics and closed form solutions. In other cases dynamic analysis or more sophisticated solutions and testing are needed. In one case involving bowl mill vibration, the problem was related to the rheology of the bed causing a self-excited vibration problem, and changing the dimensions of the grinding element or disrupting the bed solved the problem. In another case involving end rings on generators, the analysis is straightforward using the finite element technique. However, the procedure to determine the adequacy of the shrink fit for the end ring is easily estimated from closed form solutions.

Expert uses classical structural mechanics on a routine basis and at times it meets the client’s needs better than a finite element analysis. He notes that in the 1980s the power industry was concerned about life extension. A finite element analysis of transient conditions in boiler components under creep and plasticity conditions was generally too costly and too time consuming to produce a practical solution. Using his background of studying failed components, Expert wrote simplified computer software using FORTRAN that would calculate the stress from pressure and thermal transients, including the nonlinear effects of creep and plasticity. This approach has been modified for heat recovery steam generators (HRSGs).

A utility had cracking in their piping. The cracks had some suspicious features. Under further review it was found that other repairs had been performed and the hanger system as well as sections of piping had been repaired or replaced. After some monitoring it was found that the problem was caused by operation. After fixing the cracks and changing the operation on this and other units, the hanger and cracking problems stopped.After a collapse of a space frame made of bolted angles, it was found that torsional buckling was the problem, but the problem was not addressed by the AISC code. Others initiated code changes after the problem was exposed.A procedure was developed to design the high crown seal section of a boiler. The original procedure took three to four weeks. The new procedure is done in days with documentation to support what is done.A structure that is held together by springs but, due to an uneven temperature distribution, expands unevenly was analyzed to give insight to some possible problems and a logical basis to proceed with design changes.Tubes were failing in only days of operation in a fluid bed heat exchanger. When a tube was repaired others would fail. The problem was analyzed, the source of the problem was found and a redesign made. The redesign had to allow for thermal expansion, the fatigue load and work in the same size box as the original design. After the redesign the units have worked for years.

Expert may consult nationally and internationally, and is also local to the following cities: New York, New York - Yonkers, New York - Bridgeport, Connecticut - New Haven, Connecticut - Hartford, Connecticut - Stamford, Connecticut - Boston, Massachusetts - Worcester, Massachusetts - Springfield, Massachusetts - Providence, Rhode Island

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Education

Year Degree Subject Institution
Year: 1974 Degree: M. S. Subject: Civil Engineering Institution: University of Illinois
Year: 1972 Degree: B. S. Subject: Civil Engineering Institution: Worcester Polytechnic Institute

Work History

Years Employer Title Department Responsibilities
Years: 1992 to Present Employer: Undisclosed Title: Engineer Department: Responsibilities: Expert is responsible for linear and non-linear structural analysis. This can be performed using classical methods or the finite element method. Once the analysis is completed he is responsible for the evaluation. The evaluation may be to a code such as API 579, BS5500, ASME Section I or VIII, or to another standard. He is also responsible for developing life assessment techniques for existing components.

Expert's small eponymous firm addresses an extensive range of experience in a variety of engineering fields, including structural, components, piping, and materials. His work within each of these fields includes components of the theoretical, experimental, and practical engineering problem solution methods. A major strength of the company is the ability to apply analytical and numerical methods in order to ultimately provide practical engineering solutions to real world problems.

Expert's firm performs finite element analyses, but their expertise is defining the problems and performing an analysis to understand the structure so a fix can be implemented or a simplified procedure can be found. These simplified procedures may be in the form of graphs, FORTRAN programs or Microsoft Excel spreadsheets with macros. These procedures are then documented in a report.
The firm was established in 1992 and has consulted for Tennessee Valley Authority, Ontario Hydro (AMEC Foster Wheeler), State Electric Commission of Victoria in Australia, Alstom Power, GE, Energy Services, Inc., MCA Australia Pty Ltd., Siemens, Cerrey, Fuel Cell Energy, Vogt International, Lewis Australia and others.

The firm uses “STRAND7” for their general-purpose finite element work, Simflex for piping and “Staad” and/or Strand7 for steel design.

The firm meets client needs via new design, permanent or temporary fixes, plots, or FORTRAN or spreadsheet programs.
Years: 1974 to 1992 Employer: ABB-CE Title: Consulting Engineer Department: Engineering Mechanics Responsibilities: He was responsible for solutions to field failures. These failures included high temperature, high-pressure components as well as structural steel failures such as buckling. He also developed computer programs (FORTRAN) to assist others in design, analysis and life prediction including fracture mechanics programs.

Career Accomplishments

Associations / Societies
Expert is a member of the American Society of Mechanical Engineers, the American Society of Civil Engineers, and ASM International.
Licenses / Certifications
He is a P. E. in the State of Connecticut.
Awards / Recognition
Expert received the Distinguished Engineer of the Year from the Hartford Chapter of ASME for CE Fossil Systems.
He has also earned the Flame of Excellence by Combustion Engineering (1988) and has been recognized by the Connecticut Society of Professional Engineers (1989).
Publications and Patents Summary
He has six publications and one patent.

Fields of Expertise

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