The Screening Method of the Internal Defects in Wood Members of the Ancient Architectures by Hammering Sound

Defects have a serious impact on the load carrying capacity and the safety of ancient architectural wood members. Common screening methods to identify defects cause damage to this wood. To protect ancient architecture, it is necessary to develop a method that can screen for internal defects and estimate their size quickly and efficiently without destruction. This paper studied the detection mechanism of the sound hammering method for screening internal defects in wood. Wood members generated different kinds of vibration through hammering experiments, and the vibration produced by hammering wood with internal-hole defects was divided into three kinds: local surface vibration, the whole structure vibration, and defective-part vibration. The parameters and their variation of these three kinds of vibration were investigated by a mechanical vibration simplified model, and the method for screening the internal defects based on sound hammering was proposed. The feasibility of the method was verified by experiments.