Ai Bao Chai

Hybrid Fibre Polylactide Acid Composite with Empty Fruit Bunch: Chopped Glass Strands

Hybrid polylactide acid (PLA) composites reinforced with palm empty fruit bunch (EFB) and chopped strand E-glass (GLS) fibres were investigated. The hybrid fibres PLA composite was prepared through solution casting followed by pelletisation and subsequent hot compression press into 1 mm thick specimen. Chloroform and dichloromethane were used as solvent and their effectiveness in dissolving PLA was reported. The overall fibre loading was kept constant at volume fraction, , of 20% while the ratio of EFB to GLS fibre was varied between of 0 : 20 to 20 : 0. The inclusion of GLS fibres improved the tensile and flexural performance of the hybrid composites, but increasing the glass fibre length from 3 to 6 mm has a negative effect on the mechanical properties of the hybrid composites. Moreover, the composites that were prepared using chloroform showed superior tensile and flexural properties compared to those prepared with dichloromethane.

An extended two-phase model for Mullins effect in swollen rubber

Abstract It is well-known that dry rubber exhibits Mullins effect under cyclic loading condition. For swollen rubber, this response is found to strongly depend on the degree of swelling. In the present work, the modelling of the Mullins effect in swollen rubber under cyclic compressive loading is addressed. Different degrees of swelling are obtained by immersing initially dry rubber in biodiesel. The two-phase model of Mullins and Tobin [L. Mullins and N. R. Tobin: ‘Theoretical model for the elastic behaviour of filler reinforced vulcanized rubbers’, Rubber Chem. Technol. 1957, 30, 551–571] and Qi and Boyce [H. Qi and M. C. Boyce: ‘Constitutive model for stretch-°©-induced softening of the stress-stretch behavior of elastomeric materials’, J. Mech. Phys. Solids, 2004, 52, (10), 2187–2205] is considered and extended in order to capture the effect of swelling on the Mullins effect. Results show that the proposed model agree well with the experimental findings.

Dynamics of a piezoelectric energy harvester in a simulated rain environment

Rain impact energy harvesting has proven to be a feasible and potent source of alternative energy. This paper presents the development of a dynamical model for rain impact energy harvester using a piezoelectric beam in simulated rain environment. Most of the conducted works in literature were based on single droplet impact with fixed height and drop position. The main contribution of this paper is to extend the single droplet impact dynamical model by incorporating random drop sizes and drop positions. In this work, a rain simulator is used to generate artificial rain of different rain rates. Following our previous works, the water accumulation on the piezoelectric beam is modeled using added mass coefficient, and impact coefficient is integrated into the dynamical model to describe the post-impact dynamics of the droplet impact. The stochastic nature of the artificial rain is described using rain rate and drop size distribution. Two random number generators are integrated into the model, which are lognormally and uniformly distributed, to generate random numbers for droplet diameter and drop position respectively. The accuracy of the theoretical model is validated experimentally by considering four different rain rates.

Characterisation of static and dynamic responses of natural rubber bio-composites

Characterisation of static and dynamic behavioural are presented in this study of hybrid filled natural rubber. The hybrid filler consists of a combination of oil palm ash (OPA) and egg shell powder (ESP). Testing on the samples are conducted in three different aspects namely static compression testing, time dependent stress relaxation testing in compression and dynamic compression testing. Mechanical properties such as the static stiffnesses, hysteresis loss ratios, stress relaxation responses, dynamic stiffnesses, phase angles and damping ratios are reported. The static stiffness values of the hybrid filled rubber, although lower than rubber filled carbon black, presented potential if the ESP content were to be increased. The stress relaxation responses lacked consistency in the uploading stages but were fairly consistent in the unloading stages where the relaxation was close to that of rubber filled carbon black. The dynamic properties appear to be no significant improvement over that of rubber filled carbon black filled. All hybrid filled rubber samples conformed to general dynamic properties of viscoelastic material and did not display any unexpected behaviour. Collectively, there is a trend of improvement with increasing ESP content but no prominent improvement over rubber filled carbon black is observed.

The Effects of Laminate Orientation in Resin Infused Kenaf Fibre Reinforced Epoxy Composite

Water retted kenaf fibre reinforced epoxy laminates with five distinct fibre orientations, unidirectional, [+30/0/-30], [+45/0/-45], [+60/0/-60] and [90/] s were produced through resin infusion technique. The fibre weight fraction in each laminate was controlled and the effects of varying orientation in the resulting composite lamina were characterized through tensile and impact properties of the specimens. Superior tensile strength and modulus were observed for the unidirectional lamina while the orthogonal lamina [90/] s depicted the greatest resistance to impact. Specimen with higher proportion of fibres aligned parallel to the loading direction show greater enhancement in tensile strength while impact property of the lamina was found to be greater with increases in fibre orientation perpendicular to the direction of impact load.