FEASIBILITY STUDY OF PHOTOMECHANICS TECHNIQUES APPLIED TO STRESS ANALYSIS IN THREE DIMENSIONS

THE RESULTS ARE PRESENTED OF A STUDY INTO THE EXPERIMENTAL TECHNIQUES OF FULL FIELD REPRESENTATION APPLICABLE TO STRESS ANALYSIS IN THREE DIMENSIONS. THE SIMPLE CASE OF THE DISTRIBUTION OF STRESS ON THE BOUNDARY OF A CIRCULAR DISCONTINUITY IN AN ELASTIC HALF SPACE WAS EXAMINED FROM THE VIEWPOINT OF EXISTING THEORY AND VERIFIED BY MODEL ANALYSIS EMPLOYING EIGHT EXPERIMENTAL APPROACHES. THE FIRST TWO TECHNIQUES PRESENTED (PLANE STRESS AND BIAXIAL) WERE NOT APPLICABLE TO THREE-DIMENSIONAL STRESS ANALYSIS. THEY WERE COMPLETED TO PROVIDE AN EXPERIMENTAL STANDARD OF COMPARISON FOR THE OTHER TECHNIQUES AND ALSO TO DEMONSTRATE THE FLEXIBILITY OF EXPERIMENTAL STRESS ANALYSIS FOR VARYING LOAD CONDITIONS. THE SIX TECHNIQUES APPLICABLE TO STUDY OF STRESS IN THREE DIMENSIONS FALL INTO THREE BROAD GROUPS. THE FIRST GROUP INCLUDES THE FROZEN STRESS AND THE SCATTERED LIGHT APPROACHES, AND PROVIDED AN ACCURATE REPRESENTATION OF STRESS. BOTH TECHNIQUES REQUIRED SOPHISTICATED EQUIPMENT AND LONG PREPARATION TIMES, BUT BOTH WERE UNRESTRICTED IN THE SELECTION OF A PLANE FOR ANALYSIS. THE SCATTERED LIGHT TECHNIQUE IS POTENTIALLY SUPERIOR BECAUSE IT IS NON-DESTRUCTIVE AND APPLIES LOAD AT ROOM TEMPERATURE. ON THE OTHER HAND, DATA REDUCTION AND THE LOADING SYSTEM WERE LESS COMPLEX FOR THE FROZEN STRESS APPROACH. THE SECOND GROUP INCLUDES THE COMPOSITE, THE EMBEDDED POLARISCOPE AND THE EMBEDDED MOIRE MODELS. THE RESULTS WERE LESS ACCURATE THAN THE FIRST GROUP, BUT THE EQUIPMENT REQUIRED WAS MINIMAL. ONLY A SINGLE PLANE MAY BE EXAMINED, BUT THE RAPIDITY WITH WHICH THE MODELS CAN BE MADE SUGGESTS THE POSSIBILITY OF MULTIPLE MODELS. THE BONDING OF THE VARIOUS LAYERS WAS A PROBLEM, ESPECIALLY IN AREAS OF TENSION. ALTHOUGH THE COMPOSITE MODEL IS POTENTIALLY THE MOST ACCURATE OF THE GROUP, THE EFFECT OF THE INSENSITIVE LAYERS MUST BE ACCOUNTED FOR. THE EMBEDDED MOIRE MODEL PROVIDED A REPRESENTATION OF FIELD DISPLACEMENT RATHER THAN FIELD STRAIN AS IN THE OTHER MODELS. FINALLY, THE FEASIBILITY WAS INVESTIGATED FOR APPLYING THE TECHNIQUES OF HOLOGRAPHY TO A PHOTOELASTIC MODEL. THE PRELIMINARY RESULTS WERE DISAPPOINTING FROM BOTH A TECHNICAL AND AN INTERPRETATIVE VIEWPOINT. /AUTHOR/

• Supplemental Notes:
  • Tech Rpt No 4-84, 70 PP, 12 FIG, 2 TAB, 44 REF, 2 APP
• Corporate Authors:

  Construction Engineering Research Laboratory

  Army Corps of Engineers, P.O. Box 4005
  Champaign, IL  United States  61820
• Authors:
  • Hubbard, J H
• Publication Date: 1969-10

Subject/Index Terms

• TRT Terms: Deformation curve; Holography; Mathematical models; Nondestructive tests; Optical instruments; Photoelasticity; Photometry; Structural analysis; Structural models; Test procedures
• Old TRIS Terms: Polariscopes
• Subject Areas: Bridges and other structures; Geotechnology; Highways;

Filing Info

• Accession Number: 00217839
• Record Type: Publication
• Files: TRIS
• Created Date: Oct 5 1970 12:00AM