The example of General Stress Optics

High-precision 3D contouring of gears for aerospace industry General Stress Optics has developed the necessary technology to perform high precision contouring. A study was carried out in which the profile of a spur gear was measured using our technology; the results were compared to results obtained via CMM. Below we see the 3-D reconstruction of one gear tooth obtained by us. The results below show that the agreement in between the two procedures is within 1-micron.

Complex geometries or high tolerance requirements push mechanical measuring devices to their limits, with the aid of optical techniques one can obtain fast and highly accurate results. One example is the spiral bevel gear which has a very complex geometry and is difficult to measure using CMM. For that reason most of the time the qualification of a gear is determined via a 9×5 matrix test in which the points are taken along the described matrix. These points are then matched to the master that is also measured and the values are compared. If one wishes to obtain a more detailed analysis it would require increasing the matrix size and thus increase measurement time.

With our technology one can obtain a full field view of the surface and therefore is not limited to a small matrix of points. In this case in order to demonstrate the power of the technique we simplified our measurement to the same matrix and below one can see how well they agree to the points measured via CMM.

Holographic Moiré to new heights. We were able to measure displacements in the nano-meter range.The Bi-Metal Laminate composite that was measured for this experiment had a thickness of 0.008″(~200 microns). The set up that was used can be seen in the images below. An optical bench was attached to an Instron machine, a special fixture was designed to illuminate the surface while the piece experienced the compression. The field of view was 480 x 360 microns and we had resolution in the micron range. With the power of the HMSA we were able to obtain strain values and create graphs that contain the loading and unloading properties of the Bi-Metal Laminate Composite along with a 3-D representation of the strain field at specific loads.

By using the Holo-Moiré Strain Analyzer, dynamic analysis of stresses and strains of the turbine blades was possible. The resonant frequencies of the turbine (up to 55,000 Hz) were determined. The stresses and strains to the critical areas of the blades were also measured. The images provided show several stages of resonant modes.


N.A.S.A.- Investigated and provided key information to redesign the turbine engine that generates power for the the space shuttle landing system.

GM Corporation- Developed procedure to identify the vibration mode causing failure of turbine blades.

Samsung Corporation-Analyzed residual stresses during the fabrication process of silicon wafers and electronic chips using holographic moiré.

IBM- Designed an optical device to measure residual stresses in thin films applied to silicon wafers.

Apollo Project- Investigated bulkhead cylindrical junctions exposed to combined loads, cryogenic temperatures, and pressure.

N.A.S.A. Edwards- Developed holographic moiré optical techniques to measure high temperature strains in structural components.

U.S. Air Force- Wright Patterson Air Base, Material Laboratory ¯ Applied optical techniques to the study of dynamic properties of composite materials.

U.S. Air Force- Edwards Air Base, Phillips Laboratory ¯ Performed microanalysis on the damage of solid propellants.

Northrop Grunman Corporation- Analyzed residual stresses of an electronic chip at extreme temperatures.

Uniroyal- Advised on the feasibility of applying the moiré technique to the stress analysis of tires.

Goodyear- Advised on the feasibility of applying the moiré technique to the stress analysis of tires.

General Electric- Investigated vibration problems in dry cell batteries mounted on board of a satellite.

Raychem Corporation- Studied the adhesion creep characteristics of nitinol alloys and developed master curves for these alloys.

CASE Corporation- Extended the reflection moiré technique to measure the stresses on a commercial combine tractor door; measured stress concentrations on a T-Joint welded specimen using holographic moiré.

American Can- Developed an optimal solution of the buckling phenomena of tin can bottoms.

Continental Can-Determined stress concentration factors in drying cylinders for paper mills; performed 2-D and 3-D photo-elastic studies.

Chessie System Railroad- Created optical techniques to investigate the causes of surface cracking on railroad wheels.

Argonne National Laboratory-Participated as a member of the National Acid Precipitation Assessment Program Materials Effects Task Group; as a member, provided the technology of holographic moiré to study the effects of acid rain on national monuments.

Y.P.F- National Oil Company of Argentina. Assessed the conditions of two Isomax reactors that showed cracks in the bottom of the head and skirt using stress and fracture analysis.

United Nations- United Development Program. Coordinated, guided, and advised the initiation of an Experimental Mechanics Laboratory at the Structural Engineering Research Center, Council of Scientific and Industrial Research of the Indian Government in Madras, India.