Method and apparatus for measuring deformations of test samples in a testing machine

• US 4,962,669 A
• Filed: 10/06/1989
• Issued: 10/16/1990
• Est. Priority Date: 06/19/1987
• Status: Expired due to Fees

• Current Assignee: Firma CARL Schenck AG
• Original Assignee: CARL Schenck AG (Durr AG)
• Inventors: Keller, Guenter, Treusch, Werner, Hintz, Gerhart, Zoeller, Karl, Gernhart, Peter
• Primary Examiner(s): RAEVIS, ROBERT R
• Application Number:
  US07/418,400
• Time in Patent Office: 375 Days
• Field of Search: 73/800, 356/32, 356/33, 356/35.5, 356/372, 356/375, 356/383
• US Class Current: 73/800
• CPC Class Codes: G01B 11/16 for measuring the deformation in a solid, e.g. optical strain gauge
• CPC Class Codes: G01N 2203/027 Specimens with holes or notches
• CPC Class Codes: G01N 3/068 with optical indicating or recording means

Abstract

A method for measuring deformations of test samples in testing machines is carried out in a device including a light source, a detector, and signal processing circuitry. The deformations are sensed in that a light beam (2) from the light source (1) is reflected by at least one mirror (6, 6'"'"', 6a, 6b, 11a, 11b) arranged at an appropriate location, for example, directly on the test sample (4) so that test sample movements are imparted directly or indirectly to the reflecting mirror or mirrors, whereby the reflected light beam impinges upon a position detector (7) and the position of the impingement or rather its movement is determined and evaluated in an electronic evaluating circuit (8). This movement is a direct measure of the deformation. The device includes components for carrying out these method steps, whereby it is possible to measure static and/or dynamic deformations caused by tensile and compressive forces, as well as deformations resulting from twisting torques and bending moments. Furthermore, it is possible to simultaneously measure several different deformation types.

Claims

1. A method for measuring deformations caused by at least one of a tensile force and a torque moment applied as a testing load to a test sample in a testing machine, comprising:

(a) producing two sheet-like incident light beams;

(b) directing both said sheet-like incident light beams at respective narrow band-shaped mirrors directly attached to said test sample for following a movement of said test sample in response to the application of said testing load to said test sample;

(c) reflecting each of said sheet-like incident light beams by the respective band-shaped mirror to form two reflected light beams each having substantially a point cross-section;

(d) receiving each of said reflected light beams on a respective position detector whereby said reflected light beams form an impingement location on each of said position detectors;

(e) generating an output signal in each of said position detectors dependent on said impingement location to provide two output signals; and

(f) evaluating said two output signals in an evaluating circuit to determine a movement of said impingement locations in response to an application of said testing load to said test sample, said movement representing a measure of said deformation.

2. The method of claim 1, wherein at least one of said reflected light beam is a collimated point cross-section light beams.

3. An apparatus for measuring deformations caused by at least one of a tensile force and a torque moment applied as a testing load to a test sample in a testing machine, comprising light source means for emitting sheet-like incident light beams, two narrow band-shaped reflecting mirrors directly attached to said test sample for following a movement of said test sample, said narrow band-shaped mirrors reflecting said sheet-like incident light beams to form two reflected light beams each having substantially a point cross-section, position detector means for receiving said reflected light beams and generating two output signals representing a movement of at least one impingement location in response to an application of said testing load to said test sample, and electronic evaluating circuit means connected to an output of said position detector means for evaluating said output signals to determine a deformation corresponding to said movement of said impingement location of said reflected light beams on said position detector means.

4. The apparatus of claim 3, wherein said light source means comprises a laser light source.

5. The apparatus of claim 3, wherein said position detector means comprise two position detectors and said electronic evaluating circuit means comprise evaluating circuit means for evaluating both output signals generated by said two position detectors.

6. The apparatus of claim 3, wherein said position detector means comprises a one-axis linear position detector.

7. The apparatus of claim 3, wherein said position detector means comprises a two-axes planar position detector.

8. The apparatus of claim 3, wherein said position detector means operates in an analog manner.

9. The apparatus of claim 3, wherein said position detector means operates in a digital manner.