Test Procedures
Thermal Shock Test
The object of this test is to determine the ability of a cemented component to withstand abrupt temperature changes between the limits of +40°C and –40°C. The upper temperature was achieved with a normal Summers-Laboratory oven. The lower temperature was achieved with a cooling mixture. The specimen was placed in a polyethylene bag on removal from the oven before immersion to eliminate any solvent reaction.
A doublet of 6.35 mm (= 0.25 inch) Pilkington plate, 6.45 cm2 (= 1 inch) square was used. A specimen was subjected to three cycles, and examined after each. The cycles were as follows:
a) +40°C for 2 h ® -40°C for ½ h ® +40°C for 2 h ® room temperature
b) +40°C for 2 h ® -40°C for 2 h ® +40°C for 2 h ® room temperature
c) the same procedure as b)
LENS BOND withstood the temperature cycling with no adverse effects.
Mechanical Shock Test
The object of this test was to ascertain the ability of cemented components to withstand vibrations such as might be met in service conditions. The specimen was identical with that used for mechanical shock treating. It was clamped to a vibration rig and vibrated both in the plane of the cement layer and perpendicular to it. The peak acceleration was 10g over the range of 10 to 300 c/s and 8g from 300 to 500 c/s. The rate of sweep was approximately 7 c/min.
No deterioration was found in the sample after testing. The specimen was checked for resonance as well, but non was found.
In order to simulate heavier stresses on the cement layer, the specimen was again subjected to vibration over the range given above, after attaching a collar of 0.46 kg (= 1 lb) lead weighting around a cylindrical element of each flat. No damage was found in the specimen.