A study on relationship between the density, hardness and the species of malaysia woods using ultrasonic method

Abstract

Since wood is a renewable resources and Malaysia is one of the most forested countries in the world. Among tropical forest countries, Malaysia supplies 80% of the tropical sawn timber to international trade. Nowadays, ultrasonic method in determining the species of Malaysian wood is not so popular in Malaysia. There are a lot of studies and research on wood had been carried out such as microwave, x-ray scanning method and ultrasonic method. Previous research showed that many of researchers using ultrasonic methods to investigate the properties of wood. This research was done using the ultrasonic method to determine the species of Malaysian wood. The species of wood is obtained by using ultrasonic diffractometer with the frequency above 20 kHz. There are five species of wood chosen in this research, which are Seraya Kitan, Merawan, Balau, Nyatoh and Chengal. The density, hardness and the reflection of the ultrasonic wave were affected by the moisture content of each species of wood. The moisture content of each species of wood is dried up using oven at the temperature of 105 C. The rectangular wooden block size is chosen because the moisture content of the wood samples was easily to dry up due to the larger surface of the wood samples. The acoustic wave propagation phenomena in wood are related to the microstructure of the wood. The ultrasonic signal received can be determine the species of wood. The relationship between density, hardness and each species of wood is distinguished. As the density and hardness of the wood increased, the reflection of the ultrasonic wave is decreased.