Acoustic emission detection of upholstered furniture frame damage

Squeaking and creaking noise from selected components of two stationary three-seat bare sofa frames, one with glue applied to joints and the other one with no glue applied, were evaluated by subjecting them to the General Services Administration performance tests. The main purpose of this evaluation was to compare frame construction performance differences between the construction of joints with glue and without glue as it relates to the onset of squeaking. An acoustic emission apparatus utilizing microphones as noise detection sensors was used to detect the noise signals. Experimental results of recorded squeaking signal in terms of loading cycles completed until the first audible squeak indicated that, in general, the joints with no glue started squeaking earlier than the ones with glue applied, but their squeaking occurred at the same load level. The General Services Administration performance test standards define frame failures as frames suffering disability to resist testing loads applied on the frames. A frame strength performance rating is given to a tested frame based on the load level of which it passed. There was no difference in fatigue performance between glued and unglued frames. But, results of our acoustic emission study revealed that, in general, the load level corresponding to first squeak occurring was one to two load levels lower than the load level passed by a frame tested before it failed from broken components.