Abstract: Since ultrasonic velocities in anisotropic media can change by a factor of 3 or more depending on the direction of propagation, accounting for these changes is extremely important. Also many anisotropic materials are made up of multiple layers of varying orientation, hence the need to account for refraction at ply boundaries. In the present invention, an algorithm is used to calculate these velocities and travel times and properly account for refraction phenomena. Specifically a multilayer SAFT algorithm has been developed that will calculate the time shift, shift and sum A-scan waveforms in layered anisotropic media at any given depth, ply orientation, and number of plies. The algorithm showed an improvement in signal to noise ratio with synthetic data as was expected. This algorithm can be used as a replacement for homogenizing material properties in layered media and will calculate time shifts with increased accuracy since exact material properties are used.

Abstract: Disclosed herein is a method for imaging anisotropic media comprising selecting multiple points within the anisotropic media, which is to be imaged; determining an acoustic path between each selected point in the anisotropic media and a receiver position on the surface of the anisotropic media; calculating an acoustic wave velocity at all necessary points; determining an acoustic path length based on each selected point in the anisotropic media and the receiver position; determining a time delay for each acoustic wave between each image point and the receiver position on the surface of the anisotropic media; calculating a sum for each point selected based on the appropriate acoustic wave velocities and the acoustic path lengths; and generating an image of the anisotropic media using the coherent sums generated for each said image point selected.

Abstract: The present invention is a method for controlling the curing process of a composite material part in a curing vessel such as an autoclave. The method relies on the comparison of actual part parameter values to predicted part parameter values wherein the predicted values are obtained from computer simulations of the cure cycles using convective heat transfer, thermo-chemical, cure kinetics, resin flow and viscosity analytic models. The invention provides a methodology for the continuous selection and updating during the cure process of new optimal cure cycles from sets of cure cycles in response to actual material behavior during the curing process. An extended heat transfer model coupled to the thermo-chemical model accounts for convective heat transfer within curing vessel during the curing process.

Abstract: The present invention comprises a method for controlling the curing process of a composite material part in a curing vessel such as an autoclave. The method relies on the comparison of actual part parameter values to predicted part parameter values wherein the predicted values are obtained from computer simulations of the cure cycles using thermo-chemical, cure kinetics, resin flow and viscosity analytic models. The invention provides a methodology for the continuous selection and updating during the cure process of new optimal cure cycles from sets of cure cycles in response to actual material behavior during the curing process.

Abstract: A method and apparatus for non-destructively determining fiber volume fraction and resin porosity of a composite material or prepreg wherein the composite material or prepreg is moved between a roller and a roller-transducer housing. A transducer assembly is supported in the roller-transducer housing for propagating two independent acoustic waves through the composite material. A water medium is disposed in the roller-transducer housing. The two acoustic waves are propagated through the water medium, through the thickness of the roller-transducer housing and through the composite material or prepreg. The velocity of each of two acoustic waves, V.sub.1 and V.sub.2, are determined and the thickness of the composite material or prepreg is determined. The fiber volume fraction in resin porosity of the composite material or prepreg are then determined using the velocities V.sub.1 and V.sub.2, the thickness and known parameters of density, elastic modulii of the constituent material and layup sequence.

Abstract: A method and apparatus for nondestructively determining fiber volume fraction and resin porosity of a composite material constructed of at least two different constituent materials wherein the following parameters of the composite material to be tested are known: density, elastic moduli of the constituent materials and layup sequence. Two acoustic waves of different polarizations are propagated through the composite material and the acoustic waves propagated through the composite material are sensed and the velocity of each of the two acoustic waves, V.sub.1 and V.sub.2, are determined. The thickness of the composite material is determined. The fiber volume fraction and resin porosity of the composite material are then determined using the velocities, V.sub.1 and V.sub.2, the thickness and known parameters of density, elastic moduli of the constituent materials and layup sequence.

Abstract: A non-destructive method for determining elastic moduli of isotropic or anisotropic or homogeneous or nonhomogeneous material. The material is subjected to x-radiation for determining the density of the material at a sufficient number of discrete measurement points over the material to create an image of local material density variation. Ultrasonic waves are propagated through the material to determine transit times for each wave at points corresponding to the measurement points. Using the determined density and transit times for each of the measurement points, the elastic moduli at each measurement point is determined. The elastic moduli provides a means for analyzing the mechanical performance of the material. In one aspect, the determined elastic moduli are inputted into a finite element method code for determining mechanical response of the material.

Abstract: A method and apparatus for nondestructively determining fiber volume fraction and resin porosity of a composite material constructed of at least two different constituent materials wherein the following parameters of the composite material to be tested are known: density, elastic moduli of the constituent materials and layup sequence. Two acoustic waves of different polarizations are propagated through the composite material and the acoustic waves propagated through the composite material are sensed and the velocity of each of the two acoustic waves, V.sub.1 and V.sub.2, are determined. The thickness of the composite material is determined. The fiber volume fraction and resin porosity of the composite material are then determined using the velocities, V.sub.1 and V.sub.2, the thickness and known parameters of density, elastic moduli of the constituent materials and layup sequence.