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A computationally attractive algorithm is developed to provide an insight to the location and extent of structural damage. The algorithm makes use of an original finite element model and a subset of measured eigenvalues and eigenvectors. The developed theory approaches the damage location and extent problem in a decoupled fashion. First, a theory is developed to determine the location of structural damage. With location determined, an extent algorithm is then developed. The extent algorithm is a minimum rank update, which is consistent with the effects of many classes of structural damage on a finite element model. If the actual damage results in a rank p change to the finite element model, then the extent algorithm produces exact results if p eigenvalues and eigenvectors are measured exactly. In addition, the extent algorithm preserves any rigid body modes of the structure. The algorithms are demonstrated using both numerical and actual experimental data. The effects of eigenvector measurement and expansion errors are demonstrated and techniques to overcome the effects of noise are discussed.

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For certain structural testing criteria a significant proportion of tests instances are infeasible in the sense the semantics of the program implies that test data cannot be constructed that meet the test requirement. This paper describes the design and prototype implementation of a structural testing system that uses a theorem prover to determine feasibility of testing requirements and to optimize * Work performed by the author while affiliated with Kestrel Institute. Author's current affiliation is the Software Technology Center,Researchand DevelopmentDivision, Lockheed Missiles and SpaceCompany, Palo Alto, CA.Permission to copy without fee all or part of this material is granted provided that the copies are not made or distributed for direct commercial advantage, the ACM copyright notice and the title of the publication and its date appear, and notice is given that copying is by permission of the Association of Computing Machinery. To copy otherwise, or to republish, requires a fee and/or specific permission. ISSTA 94-8/94 Seattle Washington USA 0 1994 ACM 0-89791 -683-Z94/0008..$3.5O the number of test cases required to achieve test coverage. Using this approach, we were able to accurately and efficiently determine path feasibility for moderately-sized program units of production code written in a subset of Ada. On these problems, the computer solutions were obtained much faster and with greater accuracy then manual analysis. The paper describes how we formalize test criteria as control flow graph path expressions; how the criteria are mapped to logic formulas; and how we control the complexity of the inference task. It describes the limitations of the system and proposals for its improvement as well as other applications of the analysis.