System and method for nondestructive vibrational testing

• US 5,610,837 A
• Filed: 04/21/1994
• Issued: 03/11/1997
• Est. Priority Date: 04/21/1994
• Status: Expired due to Fees

• Current Assignee: Sonoco Development Inc (Sonoco Products Company)
• Original Assignee: Sonoco Products Company
• Inventors: Murphy, Joseph F.
• Primary Examiner(s): Trammell, James P.
• Application Number:
  US08/230,947
• Time in Patent Office: 1,055 Days
• Field of Search: 364/508, 364/507, 364/576, 364/579, 364/580, 73/593, 73/658, 73/660, 73/661, 73/602
• US Class Current: 702/56
• CPC Class Codes: G01N 2291/0238 Wood
• CPC Class Codes: G01N 2291/101 one transducer
• CPC Class Codes: G01N 2291/262 Linear objects
• CPC Class Codes: G01N 29/12 by measuring frequency or resonance of acoustic waves measuring frequency or resonant frequency of mechanical vibrations or acoustic waves in general G01H1/06, G01H3/04, G01H13/00; acoustic resonators G10K11/04; vibration or shock testing of structures G01M7/00

Abstract

The present invention is a system and method for nondestructive vibrational testing of a specimen, such as a paper core tube. The system analyzes transverse vibrations of the simply supported specimen. The system measures the weight change at one end of the specimen and determines the frequency of vibration and the rate of energy loss. The testing is such that the specimen can be used after testing.

Claims

1. A system for nondestructive vibrational testing of an object, comprising:

load sensor means associated with the object and having an input for receiving a voltage input and an output for providing a sensor output, said load sensor means being responsive to said voltage input and to vibration of said object for generating said sensor output;

a hardware system connected to said load sensor means and responsive to said sensor output from said load sensor means for acquiring data relative to vibration of the object;

said hardware system including voltage regulating means connected to the input of said load sensor means for providing a regulated voltage input to said load sensor means;

said hardware system further including signal conditioning means connected to the output of said load sensor means for receiving and conditioning the sensor output from said load sensor means and capable to provide an amplified signal output, analog-to-digital converter means for receiving said amplified signal output from the signal conditioning means for converting said amplified signal output to a total of 1536 data samples in digital form; and

a digital computer system responsive to said data samples, said digital computer system including means for selecting 512 data samples from the 1536 data samples, and analyzing the selected data samples.

2. The system of claim 1, wherein said computer system comprises means for determining rate of energy lost of the object.

3. The system of claim 1, wherein said means for selecting and analyzing determines at least one of core stiffness of the object and core modulus of the object.

4. The system of claim 1, wherein said computer system further comprises display means for displaying at least one of numerical results, graphical data and theoretical curves in response to said analyzed data samples, said display relating to the object.

5. The system of claim 4, wherein said computer system further includes means for calculating data corresponding to a normalized standard error and estimate for the object, said display means displaying the calculated data.

6. The system of claim 5, wherein said computer system further includes means for calculating data corresponding to at least one of frequency and log decrement of the object.

7. The system of claim 4, wherein said computer system further comprises means for storing generated data for saving original data and any additional data.

8. A system for nondestructive vibrational testing of an object, comprising:

load sensor means associated with the object and having an input for receiving a voltage input and an output for providing a sensor output, said load sensor means being responsive to said voltage input and to vibration of said object for generating said sensor output;

a hardware system connected to said load sensor means and responsive to said sensor output from said load sensor means for acquiring data relative to vibration of the object;

said hardware system including voltage regulating means connected to the input of said load sensor means for providing a regulated voltage input to said load sensor means;

said hardware system further including signal conditioning means connected to the output of said load sensor means for receiving and conditioning the sensor output from said load sensor means and capable to provide an amplified signal output, analog-to-digital converter means for receiving said amplified signal output from the signal conditioning means for converting said amplified signal output to a total of 1536 data samples in digital form; and

a digital computer system responsive to said data samples said digital computer system including means for selecting 512 data samples from the 1536 data samples and for determining data corresponding to the rate of energy lost by the object.

9. The system of claim 8, wherein the object comprises one of paper core, tubes, wood beams or steel elements.

10. The system of claim 8, wherein said computer system further includes means for carrying out fast fourier transform operations upon the 512 selected data signals.

11. The system of claim 8, wherein said computer system further includes means for calculating a nonlinear least squares procedure from the 512 selected data signals.

12. The system of claim 11, wherein said means for calculating provides data indicative of or resolution to 0.001 Hz.

13. A system for nondestructive vibrational testing of an object, comprising:

load sensor means associated with the object and having an input for receiving a voltage input and an output for providing a sensor output, said load sensor means being responsive to said voltage input and to vibration of said object for generating said sensor output;

a hardware system connected to said load sensor means and responsive to said sensor output from said load sensor means for acquiring data relative to vibration of the object;

said hardware system including voltage regulating means connected to the input of said load sensor means for providing a regulated voltage input to said load sensor means;

said hardware system further including signal conditioning means connected to the output of said load sensor means for receiving and conditioning the sensor output from said load sensor means and capable to provide an amplified signal output, analog-to-digital converter means for receiving said amplified signal output from the signal conditioning means for converting said amplified signal output to a total of 1536 data samples in digital form; and

a digital computer system including means for setting parameters for the object prompting the computer system for data by positioning an object inputting geometry and weight data of the specimen, checking a voltage dial setting of said signal conditioning means, inputting a sampling rate,

setting initial sample data I_o equal to the 512th sample point;

displaying 512 selected data samples of 1536 generated data samples starting with I_o ;

waiting for a key press of input commands; and

prompting the computer system again for data.

14. The system of claim 13 wherein prompting the system further comprises:

saving any previous data sampled;

providing a directory of saved files;

comparing a prompt of the system to the saved files and determining if a specimen has previously stored data;

displaying the geometry and weight data of the previously stored data;

reediting comments of the previously stored data;

setting I_o equal to a stored value; and

returning to the displaying of the geometry and weight data.

15. The system of claim 13, wherein waiting for the key press of input commands includes one of the following:

receiving a command generated by an input key and returning the computer system to the step of prompting;

receiving a command to save data, requesting a file name with comments, and returning the computer displaying;

receiving a command to calibrate the computer system, and returning to the checking;

receiving a command to resample a same specimen or list the data file for replay;

receiving a command to increase the starting position by 64 samples, and returning to the displaying of the geometry and weight data; and

receiving a command to decrease the starting position by 64 samples, and returning to the displaying of the geometry and weight data.

16. The system of claim 13 wherein waiting for the key press of input commands further comprises:

receiving a command to analyze sampled data;

displaying the sampled data;

saving the results; and

returning to the waiting for the key press of input commands.

17. A method for nondestructive vibrational testing, comprising the steps of:

setting parameters of a computer system;

checking for a math co-processor in the computer system;

prompting the computer system for data by positioning a specimen, inputting geometry and weight data of the specimen, checking a voltage dial setting, inputting a sampling rate, sending the data to a remote unit, waiting for an initial sample, and sending the initial sample to a host computer;

setting initial sample data I_o equal to the 512th sample point;

displaying 512 data points of 1536 possible data points starting with I_o ;

waiting for a key press of input commands; and

prompting the computer system again for data.

18. The method for nondestructive vibrational testing according to claim 17, wherein the step of prompting the system further comprises the steps of:

saving any previous data sampled;

providing a directory of saved files;

comparing a prompt of the system to the saved files and determining if a specimen has previously stored data;

displaying the geometry and weight data of the previously stored data;

reediting comments of the previously stored data;

setting I_o equal to a stored value; and

returning to said step of displaying the geometry and weight data.

19. The method for nondestructive vibrational testing according to claim 17, wherein the step of waiting for the key press of input commands comprises one of the following steps:

receiving a command generated by an input key and returning the computer system to the step of prompting;

receiving a command to save data, requesting a file name with comments, and returning the computer system to the step of displaying;

receiving a command to calibrate the computer system, and returning to the step of checking;

receiving a command to resample a same specimen or list the data file for replay;

receiving a command to increase the starting position by samples, and returning to the step of displaying the geometry and weight data; and

receiving a command to decrease the starting position by 64 samples, and returning to the step of displaying the geometry and weight data.

20. The method for nondestructive vibrational testing according to claim 17, wherein the step of waiting for the key press of input commands further comprises the steps of:

receiving a command to analyze sampled data;

displaying the sampled data;

saving the results; and

returning to the step of waiting for the key press of input commands.