The world population have been continuously increasing and it was predicted to be 9.2 billion by 2040, this will increase the utilization of wood fibre and wooden products consumption. Many wood industry sectors are interested in planting rubber tree for latex and harvesting logs when the latex is lasted. i.e. Laos has 446,000 ha of plantation which covered by rubber tree area of 58% out of acacia, eucalyptus species, and teak (Smith et al. 2020).
Normally, timber mechanical properties were tested by using Universal Testing Machine based on market’s requirements of testing standard for MOE and The standard test method to determine the MOE of timber in Australia is the static bending test, according to (AS/NZS 4063.1, 2010).
Predicting the MOE of timber has become a crucial issue in the operational value chain and received considerable attention in recent years in terms of grading and pre-sorting. However, non-destructive techniques (NDT) to characterise wood and other materials are gaining popularity due to being non-destructive, comparatively faster, and not necessarily confined to a laboratory. A newly developed smartphone application called SMART THUMPER™, the application was developed by Mississippi State University’s Department of Sustainable Bioproducts. Since it is a smartphone application, this approach has the potential to be an easy-to-use, low-cost, and portable means of obtaining indicative stiffness properties of timber, which will make it readily available to a wider community. The SMART THUMPER™ application uses a well-established and published relationship to calculate the MOE in the longitudinal direction from natural frequencies of soundwave, density, and dimension of the sample expressed as Eq. 1,
$${E}_{L}=4\rho {L}^{2}{\left({f}_{L,n}/n\right)}^{2}$$
1
where ρ is the density (kg/m3), L is the length (m), fL,n is the nth longitudinal mode frequency, and n refers to the mode number (1, 2, 3, etc.). The application uses the first mode, i.e., n = 1. The application calculates density based on the mass and dimension input by user.
Many wood species have been tested using the application, for instance, Sawn wood of Spotted gum, Blackbutt, Jarrah, Messmate, Pine, and Southern Pine, the results shows a strong positive correlation (R2 = 0.97) between BING© and SMART THUMPER™ MOEs, indicating that the SMART THUMPER™ application can estimate the MOE of timber with various densities (Kumar et al., 2021).
However, the feasibility, accuracy, and limitations of the SMART THUMPER™ application in terms of measuring the indicative stiffness of timber needs to be identified and understood for different timber species and sample conditions to support wider adoption. The objective of this study was to investigate the results of estimating modulus of elasticity of rubber plantation timber based on the SMART THUMPER™ application and the universal testing machine.