Measurement of Stress Distributions in Adhesive Bonded Joints.
Final rept. 17 Aug 81-28 Feb 86,
DENVER UNIV COLO COLL OF ENGINEERING
Pagination or Media Count:
Triaxial stresses were determined by X-ray diffraction in the Aluminum adherend of a single lap joint at an average depth of .033 mm from the Aladhesive interface. Access to the joint was gained non-destructively by making one adherend of Be relatively transparent to Cukalpha radiation and the other of Al alloy relatively opague. The incident X-ray beam passed through the Beryllium and the adhesive FM-73M, American Cyanamid Co. and was diffracted from the Al adherend adjacent to the Aladhesive interface. Changes in the lattice spacing of the 511 333 reflection of Al compared with the stress free spacing were used to determine the strain and stress tensors along the bond. Measurements were made in the as-cured and loaded conditions, and on specimens containing an intentional debond. Results for the loaded condition were compared with Texagap-2D finite element calculations for a nominally identical specimen at a depth .033 mm into the Al adherend. The comparison showed a general agreement in trends and magnitudes for all the stress components except at the extremities of the bond. In particular, the measured peel stress at one extremity was substantially larger than the calculated peel stress. The discrepancies between measured and calculated stresses can be explained qualitatively by the presence of an unintentional debond of depth 0.5 mm at the one extremity. Keywords Adhesive bonds. X-ray stress, Curing stress, Residual stress, Acoustic emission, Al 6061, Al 5052, Single lap joint.
- Couplers, Fasteners and Joints