Natural Frequency of Lightweight Composite Slabs Based On Experimental Study and Numerical Modelling

Recently, lightweight composite slabs have become increasingly popular. Lightweight composite slabs are an innovation that provides a better and more convenient construction method for floor systems. Under dynamic loads, lightweight composite slabs may experience meagre inertia forces due to poor stiffness or low mass. Compared to conventional composite slabs, lightweight composite slabs are 40% lighter and more susceptible to structural resonance. Therefore, the vibration behaviour must be controlled to avoid discomfort issues. This study investigates the natural frequency of lightweight composite slabs through experimental study and numerical modelling. In the experimental study, lightweight composite slabs were prepared for the hammer-impact test. The slab thickness ranges from 100 mm to 200 mm. In numerical modelling, lightweight composite slabs were modelled in SAP2000 using a unique technique called the simplified equivalent plate model. The effective material properties were derived from the rule of mixtures and depend exclusively on elastic properties with strength characteristics. The results of the experimental study and numerical modelling agree positively. The natural frequency decreased with slab thickness, signifying that the natural frequency is dominated by mass rather than stiffness. Overall, the natural frequency of lightweight composite slabs is around 27.23Hz to 31.45Hz

Natural Frequency of Lightweight Composite Slabs Based On Experimental Study and Numerical Modelling

Recently, lightweight composite slabs have become increasingly popular. Lightweight composite slabs are an innovation that provides a better and more convenient construction method for floor systems. Under dynamic loads, lightweight composite slabs may experience meagre inertia forces due to poor stiffness or low mass. Compared to conventional composite slabs, lightweight composite slabs are 40% lighter and more susceptible to structural resonance. Therefore, the vibration behaviour must be controlled to avoid discomfort issues. This study investigates the natural frequency of lightweight composite slabs through experimental study and numerical modelling. In the experimental study, lightweight composite slabs were prepared for the hammer-impact test. The slab thickness ranges from 100 mm to 200 mm. In numerical modelling, lightweight composite slabs were modelled in SAP2000 using a unique technique called the simplified equivalent plate model. The effective material properties were derived from the rule of mixtures and depend exclusively on elastic properties with strength characteristics. The results of the experimental study and numerical modelling agree positively. The natural frequency decreased with slab thickness, signifying that the natural frequency is dominated by mass rather than stiffness. Overall, the natural frequency of lightweight composite slabs is around 27.23Hz to 31.45Hz

Assessment of plant species diversity at Pasir Tengkorak Forest Reserve, Langkawi Island, Malaysia

Plant species diversity of a logged-over coastal forest with in the Pasir Tengkorak Forest Reserve, Langkawi Island, Malaysia was assessed by establishing a 1-ha plot. All plants above 1.0 cm dbh (diameter of a tree at breast height), or 4.5 feet above ground level, the accepted point of diameter measurement for most trees were enumerated. Species diversity was defined as a combination of species richness and evenness. The jackknife estimate and species- area curve were applied to estimate the species richness. It was estimated using Simpson’s index of diversity, Shannon-Weiner function and Brillouin index. Simpson’s measure of evenness, Camargo’s index of evenness and Smith and Wilson’s index of evenness were also used to estimate species evenness. A total of 3414 individual trees representing 120 species, 81 genera and 31 families were recorded. Species with highest relative abundance were Swintonia sp1(0.12), Garcinia eugnifolia(0.09) and Syzygium sp1(0.05). The jackknife estimate of species richness was 132.9 and the regress ion equation to estimate species richness was LnSˆ=2.53 + 0.24 ln (A)with r2=96.0 %. Species diversity was high with Simpson’s index of diversity with a value of 0.96, while Shannon-Weiner index was 5.42 and Brillouin’s Index was 5.14. However, Simpson’s measure of evenness, Camargo’s index of evenness and Smith and Wilson’s index of evenness were 0.264, 0.378, and 0.41 9, respectively. Results indicated that species richness and species diversity were high, but evenness was low in this logged-over coastal forest

Effect of Wood Dust Fibre Treatments Reinforcement on the Properties of Recycled Polypropylene Composite (r-WoPPC) Filament for Fused Deposition Modelling (FDM)

The efficacy of wood dust fibre treatment on the property of wood dust reinforced recycled polypropylene composite (r-WoPPC) filament was investigated. The wood dust fibre was treated using alkali, silane, and NaOH-silane. The treated wood fibre was incorporated with r-PP using a twin-screw extruder to produce filament. The silane treatment on wood dust fibre enhances interfacial bonding between wood fibre and recycled PP; hence, a filament has the highest wire pull strength, which is 35.2% higher compared to untreated and alkaline-treated wood dust filament. It is because silanol in silane forms a siloxane bond that acts as a coupling agent that improves interfacial bonding between wood dust fibre and recycled PP. The SEM micrograph of the fracture structure reveals that treated silane has strong interfacial bonding between wood dust fibre and recycled PP, having minimal void, gap, and good fibre adhesion. The water absorption test results indicate that filament with treated wood dust absorbs less water than filament with untreated wood because the treatment minimizes the gap between wood fibres and recycled PP. The FTIR analysis identified the presence of silane on the wood dust surface for silane-treated wood dust. The DSC studies suggest that the temperature range 167–170 °C be used in the extrusion machine to produce r-WoPPC filament. As a result, r-WoPPc filaments containing silane-treated wood dust have better mechanical properties and have a greater potential for usage in FDM applications