Estimating Young’s Modulus and Modulus of Rupture of Coconut Logs by Small Clear Specimen Flexure Testing

Abstract

Mechanical properties of coconut logs must be available to make a good building design using the material. The properties should be measured by full scale testing, which is almost impossible in Indonesia today because it costs expensive and needs high power equipments. This research develops a theory to estimate Young’s modulus (E) and modulus of rupture (SR) of coconut-logs by reconstruction methods. The flexural testing is conducted to small clear specimen. Coconut-logs are reconstructed by replacing each small clear specimen on its natural place theoretically, and then the properties are estimated by mechanics, statistics, calculus and geometric analytic equation. This method is successful estimating Young’s modulus and modulus of rupture of coconut logs based on small clear specimen flexural testing. The average estimated Young’s modulus value of coconut logs cut from 1st and 2nd tree, are 8,118 N/mm2 and 8,596 N/mm2. The average modulus of rupture is 124 N/mm2 and 118 N/mm2 respectively. The two properties have similar tendency, so they have high correlation. KEYWORDS: coconut logs, modulus of rupture, reconstruction, Young’s modulus