Adhesive shear strength test apparatus

An adhesive shear strength test apparatus comprising:

• a first cylindrical rod having a bore of a certain diameter and a certain depth reamed into a first end along a longitudinal axis of the rod and having a counterbore of a diameter larger than the diameter of the bore reamed to a depth less than the depth of the bore into said first end along the longitudinal axis;
• a second cylindrical rod having a diameter essentially equal to the diameter of the bore, an insertion end of the second rod being inserted into the bore of the first rod, the second rod being aligned with the longitudinal axis of the first rod;
• adhesive placed within a cylindrical space formed between the second rod and an inner surface of the counterbore, the adhesive forming a bond between the first rod and the second rod such that the adhesive is subjected to a pure shear load when the first and second rods are subjected to a tensile load applied along the longitudinal axis;
• a reservoir of a diameter smaller than the diameter of the bore drilled to a depth greater than the depth of the bore into the first end of the first rod along the longitudinal axis thereof;
• and
• a drain tap drilled into the first end of the first rod transversely to the longitudinal axis thereof and intersecting the reservoir, the reservoir and drain tap allowing full engagement of the second rod within the bore by facilitating removal of excess adhesive and bleeding of air from the apparatus when the second rod is inserted into the bore.

A method for testing an adhesive bond in pure shear comprising the steps of:

• providing a cylindrical holder rod;
• reaming a bore of a certain diameter a distance from an end of the holder rod along a longitudinal axis thereof;
• reaming a counterbore of a diameter larger than the diameter of the bore to a lesser distance than the bore along the longitudinal axis of the holder rod;
• providing a cylindrical insertion rod having a diameter essentially equal to the diameter of the bore;
• providing adhesive within the counterbore;
• inserting the insertion rod through the adhesive in the counterbore and into the bore, the insertion rod being aligned with the longitudinal axis of the holder rod, the adhesive filling a cylindrical space of uniform thickness between the insertion rod and an inner surface of the counterbore;
• allowing the adhesive to cure forming a cylindrical bond between the insertion rod and the inner surface of the counterbore;
• subjecting the holder rod and the insertion rod to increasing tensile force tending to pull the insertion rod from within the bore of the holder rod, the tensile force being resisted by shear within the cylindrical bond;
• and
• measuring the strength of the shear until failure of the bond.

A method for testing an adhesive bond in pure shear comprising the steps of:

• providing a cylindrical holder rod;
• reaming a bore of a certain diameter a distance from an end of the holder rod along a longitudinal axis thereof;
• reaming a counterbore of a diameter larger than the diameter of the bore to a lesser distance than the bore along the longitudinal axis of the holder rod;
• drilling a reservoir of a diameter smaller than the diameter of the bore to a greater distance than the bore along the longitudinal axis of the holder rod;
• drilling a drain tap transverse to the longitudinal axis of the holder rod intersecting with the reservoir;
• providing a cylindrical insertion rod having a diameter essentially equal to the diameter of the bore;
• providing adhesive within the counterbore;
• inserting the insertion rod through the adhesive in the counterbore and into the bore, the insertion rod being aligned with the longitudinal axis of the holder rod, the adhesive filling a cylindrical space between the insertion rod and an inner surface of the counterbore;
• allowing excess adhesive and air to flow through the reservoir and out of the drain tap as the insertion rod is inserted into the bore;
• flushing excess adhesive from the reservoir and the drain tap when the insertion rod is fully within the bore;
• allowing the adhesive to cure forming a cylindrical bond between the insertion rod and the inner surface of the counterbore;
• subjecting the holder rod and the insertion rod to increasing tensile force tending to pull the insertion force being resisted by shear within the cylindrical bond;
• and
• measuring the strength of the shear until failure of the bond.