Acoustic pressure load conversion method to vibration spectra

• US 6,363,789 B1
• Filed: 05/31/2000
• Issued: 04/02/2002
• Est. Priority Date: 05/31/2000
• Status: Expired due to Term

• Current Assignee: The Boeing Co.
• Original Assignee: The Boeing Co.
• Inventors: Young, Gerould K., Landmann, Alan Edqar, Lee, Jung-Chaun, Rassaian, Mostafa
• Primary Examiner(s): Williams, Hezron
• Assistant Examiner(s): MILLER, ROSE MARY
• Application Number:
  US09/584,646
• Time in Patent Office: 671 Days
• Field of Search: 736/63, 736/62, 738/49, 738/50, 738/51, 738/52, 700/95, 700/97, 700/98, 700/103, 700/108, 700/109
• US Class Current: 73/663
• CPC Class Codes: G01M 7/00 Vibration-testing of structures; Shock-testing of structures G01M9/00 takes precedence
• CPC Class Codes: G01N 2203/0073 Fatigue

Abstract

A method is provided for testing structural-acoustic systems using a shaker table. The method includes subjecting a panel structure design to a computational acoustic load and a computational vibration load. The method then computes the ratio of the panel structure maximum response to the acoustic load to the panel structure maximum response to the vibration load. The ratio of these two maximum responses provides a conversion factor for linking an acoustic environment to a vibration environment. Using the conversion factor, the method converts a sonic pressure load for the panel structure to a vibration load. The vibration load is then applied to a panel structure using a shaker table.

Claims

1. A method of determining a link for relating a first environment to a second environment comprising:

subjecting a panel structure model to a computational first load;

subjecting the panel structure model to a computational second load;

determining a maximum response of the panel structure model to the first load;

determining a maximum response of the panel structure model to the second load; and

determining a ratio of the maximum responses, said ratio being the link relating the first environment to the second environment.

2. The method of claim 1 wherein the panel structure model comprises a finite-element model of a panel structure and the method further comprises:

obtaining a first environment load to test against the finite-element model;

applying the ratio of the maximum response to the first environment load to convert the first environment load to a second environment load;

subjecting the finite-element model to the second environment load; and

determining a stress response of the finite-element model due to the second environment load.

3. The method of claim 2 wherein the first environment load further comprises one of an acoustic pressure load and an acceleration load and the second environment load further comprises the other of the acoustic pressure load and the acceleration load.

4. The method of claim 1 wherein the computational first load further comprises a 1 psi uniform pressure load.

5. The method of claim 1 wherein the computational second load further comprises a 1 g negative base acceleration load.

6. The method of claim 1 wherein the computational second load is generated by mode-acceleration.

7. The method of claim 1 further comprising applying pressure load boundary conditions to the panel structure model prior to determining the ratio of maximum responses.

8. The method of claim 1 further comprising applying acceleration load boundary conditions to the panel structure model prior to determining the ratio of maximum responses.

9. A method of testing a panel structure for sonic fatigue using a shaker table comprising:

subjecting a model of the panel structure to a computational acoustic load;

applying acoustic load boundary conditions to the model;

determining a maximum pressure response of the model to the acoustic load and acoustic boundary conditions;

subjecting the model to a computational acceleration load;

applying acceleration load boundary conditions to the model;

determining a maximum acceleration response of the model to the acceleration load and acceleration boundary conditions;

determining a ratio of the maximum pressure response to the maximum acceleration response;

selecting a sonic pressure load for testing against the panel structure;

converting the sonic pressure load to a pressure power spectral density;

applying the ratio of the maximum pressure response to the maximum acceleration response to the pressure power spectral density to convert the pressure power spectral density to an acceleration power spectral density;

generating input for the shaker table according to the acceleration power spectral density;

securing the panel structure to the shaker table;

applying the input to the shaker table; and

monitoring the response of the panel structure to the input.

10. The method of claim 9 wherein the acoustic load further comprises a 1 psi uniform pressure load.

11. The method of claim 9 wherein the acoustic load has a magnitude accounted for by mode-superposition.

12. The method of claim 9 wherein the acceleration load further comprises a 1 g negative base acceleration load.

13. The method of claim 9 wherein the acceleration load has a response generated by mode-acceleration.