Apparatus for in-situ nondestructive measurement of young's modulus of plate structures
First Claim
1. An apparatus for quantitatively evaluating a material stiffness of a composite laminate plate along an in-plane direction, the plate having a plurality of plies arranged in a balanced symmetric ply lay-up and having opposite major surfaces defining a thickness of the plate therebetween, the apparatus comprising:
- a transducer for initiating an elastic extensional-mode wave that propagates through the plate along said in-plane direction;
a sensor, spaced apart from said transducer by a distance d, for detecting arrival of the extensional-mode wave; and
a processor, responsive to said transducer and said sensor, for calculating a material stiffness of the plate along said in-plane direction based on the distance d and an elapsed time between the initiation of the extensional-mode wave by said transducer and the arrival of the extensional-mode wave at said sensor.
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Accused Products
Abstract
A method and apparatus for determining stiffness of a plate-like structure including a monolithic or composite laminate plate entails disposing a device for generating an acoustical pulse against a surface of the plate and disposing a detecting device against the same surface spaced a known distance from the pulse-generating device, and using the pulse-generating device to emit a pulse so as to create an extensional wave in the plate. The detecting device is used to determine a time of flight of the wave over the known distance, and the wave velocity is calculated. A Young'"'"'s modulus of the plate is determined by a processor based on the wave velocity. Methods and apparatus for evaluating both isotropic plates and anisotropic laminates are disclosed.
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Citations
20 Claims
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1. An apparatus for quantitatively evaluating a material stiffness of a composite laminate plate along an in-plane direction, the plate having a plurality of plies arranged in a balanced symmetric ply lay-up and having opposite major surfaces defining a thickness of the plate therebetween, the apparatus comprising:
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a transducer for initiating an elastic extensional-mode wave that propagates through the plate along said in-plane direction;
a sensor, spaced apart from said transducer by a distance d, for detecting arrival of the extensional-mode wave; and
a processor, responsive to said transducer and said sensor, for calculating a material stiffness of the plate along said in-plane direction based on the distance d and an elapsed time between the initiation of the extensional-mode wave by said transducer and the arrival of the extensional-mode wave at said sensor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. An apparatus for quantitatively evaluating a change in Young'"'"'s modulus of a composite laminate plate along an in-plane direction, the plate having a plurality of plies arranged in a balanced symmetric ply lay-up and having opposite major surfaces defining a thickness of the plate therebetween, the apparatus comprising:
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a transducer for imparting energy to the plate so as to cause extensional-mode waves to originate and propagate along the plate in said in-plane direction;
a sensor for detecting arrival of a respective extensional-mode wave, said sensor spaced a predetermined distance d in said in-plane direction from said transducer; and
a processor for determining an elapsed time t required for a respective extensional-mode wave to travel the predetermined distance d during both a first test from which t1 is determined and a subsequent second test from which t2 is determined, and for separately calculating Young'"'"'s modulus for the plate along said in-plane direction for both the first and second tests, said processor also adapted to calculate a change in Young'"'"'s modulus for the plate along said in-plane direction based on a degree of difference of the times t1 and t2. - View Dependent Claims (15, 16, 17, 18, 19, 20)
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Specification