Systems and methods to determine elastic properties of materials
First Claim
1. A system for determining one or more elastic properties of a material, the system comprising:
- a first input means for receiving a first input signal representative of a driving force exerted on the material by an actuator at a driving-point;
a second input means for receiving a second input signal representative of a driving-point velocity corresponding to the driving force;
a third input means for receiving a third input signal representative of a driving-point displacement corresponding to the driving force;
a signal generator means for generating a basis function signal for each one of a set of basis functions, the set of basis functions corresponding to the terms of a differential equation model of the motion of the driving-point, and each basis function comprising a function of any one or more of the input signals; and
a processor means for analyzing the set of basis function signals in relation to the first input signal to determine coefficients of a linear combination of the basis function signals which best fits the first input signal, one or more of the coefficients then being representative of a value of one or more elastic properties of the material.
0 Assignments
0 Petitions
Accused Products
Abstract
The present invention provides systems and methods to use a measured driving-point response of a nonlinear material to determine one or more elastic properties of the material. The present invention takes advantage of the full information represented by the transient component, the steady-state component, the anharmonic components, and the nonlinear response components of a measured driving-point response of a real nonlinear material, without limitation in the use of large-amplitude forces. The elastic properties are determined by forming and solving a time-domain system of linear equations representing a differential equation model of the driving-point motions of the material. Based on a single, short duration, large-amplitude driving point measurement, both linear and nonlinear properties can be determined; both large-amplitude and near-zero amplitude properties can be determined; and elastic-wave speed and elastic moduli and their variation with depth can be determined. The present invention also provides a system and a method to filter an input signal to either attenuate or preserve each of one or more selected harmonic components that are harmonics of a phase reference signal.
-
Citations
25 Claims
-
1. A system for determining one or more elastic properties of a material, the system comprising:
-
a first input means for receiving a first input signal representative of a driving force exerted on the material by an actuator at a driving-point;
a second input means for receiving a second input signal representative of a driving-point velocity corresponding to the driving force;
a third input means for receiving a third input signal representative of a driving-point displacement corresponding to the driving force;
a signal generator means for generating a basis function signal for each one of a set of basis functions, the set of basis functions corresponding to the terms of a differential equation model of the motion of the driving-point, and each basis function comprising a function of any one or more of the input signals; and
a processor means for analyzing the set of basis function signals in relation to the first input signal to determine coefficients of a linear combination of the basis function signals which best fits the first input signal, one or more of the coefficients then being representative of a value of one or more elastic properties of the material. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
-
-
19. A system for determining one or more elastic properties of an in situ material, the system comprising:
-
a first input means for receiving a first input signal representative of a driving force exerted on the material by an dynamic actuator at a driving-point;
a second input means for receiving a second input signal representative of a driving-point velocity corresponding to the driving force;
a third input means for receiving a third input signal representative of a driving-point displacement corresponding to the driving force;
a signal generator means for generating a basis function signal for each one of a set of basis functions, the set of basis functions corresponding to the terms of a force balance differential equation model of the motion of the driving-point, the differential equation model comprising a nonlinear spring-damper system represented by polynomial function of the driving-point displacement and a polynomial function of the driving-point velocity, and each other basis function comprising a function of any one or more of the input signals; and
a processor means for analyzing the set of basis function signals in relation to the first input signal to determine coefficients of a linear combination of the function signals which best fits the first input signal, wherein each coefficient corresponding to a displacement term is then representative of a stiffness property of the material, and each coefficient corresponding to a velocity term is then representative of a viscosity property of the material.
-
-
20. A system for filtering an input signal, the system comprising
a phase detector for generating a phase-sample timing signal representative of a sequence of times corresponding to substantially equal intervals of phase of a phase reference signal, wherein the equal intervals of phase comprise an integer number N of phase intervals per cycle of the phase reference signal; -
a sampler for sampling the input signal at the sequence of times corresponding to the phase-sample timing signal, thereby generating a phase-sampled signal; and
a filter adapted for filtering the phase-sampled signal to generate a filtered signal, wherein the filter is adapted to either attenuate or preserve each of one or more selected components. - View Dependent Claims (21, 22, 23, 24, 25)
-
Specification