Characterization of environmental and machinery induced vibration transmissivity

• US 20020129653A1
• Filed: 01/30/2001
• Published: 09/19/2002
• Est. Priority Date: 01/30/2001
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Seth, Brij B., Liasi, Evangelos, Muniyappa, Balachandra
• Granted Patent: US 6,575,034 B2
• Time in Patent Office: Days
• US Class Current: 73/594
• CPC Class Codes: G01M 7/00 Vibration-testing of structures; Shock-testing of structures G01M9/00 takes precedence

Abstract

A method that simultaneously monitors and captures vibration acceleration signals at locations comprising at least one site sourcing environmental excitations and a target site, which target site is selected from a planned machinery foundation site or one or more sites interfacing between elements of machinery to be placed on such foundation; extracting amplitude and frequency data from the frequency representations of the domains of such signals; quantifying displacement excitations from such data at such locations; and providing transmissivity ratios along the vibration path by summing the displacement excitations at different frequencies at each of the locations and then ratioing the sum at either the planned machinery foundation site or at a selected joint site with the sum at the environmental excitation site, thereby indicating the relative vibration stiffness between such sites. Such transmissivity ratios can then be used to modify the design of the proposed foundation, and/or the design of interfacing elements of the machine.

Claims

1. A method of identifying vibrations transmitted through ground soil between an environmental vibration site and a target site, comprising:

(a) simultaneously monitoring and capturing vibration accelerometer signals at said environmental vibration site and at said target site;

(b) extracting amplitude and frequency data from the frequency representations of the domains of said signals;

(c) quantifying displacement excitations from such data at said locations; and

(d) providing transmissivity ratios by summing said displacement excitations at different frequencies at each of said locations and ratioing the sums at said sites, thereby indicating the relative vibrational stiffness between such ratioed sites.

2. The method as in claim 1, in which the quantification of displacements of step (c) is carried out by the following mathematical analysis:

X_s=∫

∫

a_s (t) dtX_t=∫

∫

a_t (t) dt

3. The method as in claim 2, in which step (d) is carried out by ratioing X_t/X_s.

4. A method of characterizing environmental vibration transmissivity for machinery to be installed on a planned machinery foundation, the method comprising:

(a) simultaneously monitoring and capturing vibration acceleration signals at an earth ground site through which environmental vibrations are transmitted, and a target site which is selected from a planned machinery foundation site and/or one or more sites containing joints between elements of said machinery to be placed on said foundation;

(b) extracting amplitude and frequency data from the frequency representations of the domains of said signals;

(c) quantifying displacement excitations from such data at said locations; and

(d) providing transmissivity ratios by summing said displacement excitations at different frequencies at each of said locations and ratioing the sum at either said machinery foundation site or at a selected joint site, to the sum at the environmental excitation source site, thereby indicating the relative vibrational transmissivity between such ratioed sites.

5. The method as in claim 4, in which said method further comprises step (e) which consists of modifying the design of said foundation and/or joints to improve the performance of said foundation or machinery.

6. The method as in claim 5, in which said transmissivity ratios, in step (e), guide the design of the foundation by identifying and proportioning the use of vibration dampening materials in the selection of building materials for the foundation.

7. The method as in claim 5, in which said transmissivity ratios, in step (e), guide the design and use of isolation devices for the machine base.

8. The method as in claim 5, in which said transmissivity ratios, in step (e), guide the design for improving said machine elements to achieve the desired stiffness characteristics between elements.

9. The method as in claim 5, in which said transmissivity ratios, in step (e), guide the selection of tuning gains in motors employed by motor driven joints between elements of the machine to dampen undesirable vibrations being tramsmitted.

10. The method as in claim 4, in which the extraction step (b) is carried out by Fourier transformation.

11. The method as in claim 4, in which the quantification of displacements of step (c) is carried out by the following mathematical analysis:

X_s=∫

∫

a_s (t) dtX_t=∫

∫

a_t (t) dt

12. The method as in claim 11, in which step (d) is carried out by ratioing X_t/X_s.

13. The method has in claim 4, in which said environmental vibrational source is selected from a remote manufacturing dynamic machine or the drive motor of the machine being analyzed.