Testing the joint strength of wooden rests on bed frames

The article presents the results of comparative research on the joint strength of wooden bed rests fixed to the bed sides. The test was done on three sample groups made of chipboards coated with fine 18 mm veneer and finished with nitrocellulose varnish. The beech (Fagus silvatica, L.) supports in the first sample were fixed with Φ 3x45 mm screws and glue varnished surfaces. The second sample group had rests fastened with two-hand Φ 1.3; 8x30 staples and glue for varnished surfaces. The samples of the third gorup were joined with Φ 8x32 mm beech dowels. The testing was done in the labs of the Faculty of Forestry Zagreb University. The results of testing for static and dynamic load have revealed that the highest joint strength for practical use was achieved by glued dowels where the mean breakforce per joint unit was 2399 N. A slightly lower strength was displayed by the screwed samples, due to different screw positioning. The break force per screw ranged from 1471 N to 1695 N. The poorest results were achieved with the staple/glue samples ranging from 925 N to 1137 N. The same samples were tested on dynamic load by means of the 50 kg-mass falling down from a height of 200 m, with a frequency of 1440 blows/h. The samples endured up to 22,218 blows before the rests were separated from the sides.