Power-Based Estimation of Cutting Forces During Turning of Aluminium Biomass Ash Particulate Composite

Aluminum-Biomass Ash Particulate Composite is a reinforced composite material of aluminum and biomass ash particles. The composite offers significant mechanical properties advantage and low-cost advantage because of the use of waste as the reinforcement material and as a result, it is gaining increased industrial attention because of the many advantages they offer over conventional Aluminium Matrix Composites. These materials are mostly accessed on the basis of their mechanical, microstructural and chemical properties with very limited interest on their machinability relative to the base material. The specific cutting force coefficients and cutting forces of the composite were estimated during CNC turning operations and the effects of reinforcement on the machinability responses were studied. In this work, power-based force estimation approach was adopted for this purpose for the first time. This approach is less expensive compared to the dynamometric approach since it relies on adapting existing equipment developed for other purposes. This was done by measuring the electric power of the direct-drive motors of the CNC machine during the turning process and the power measurements were analyzed to obtain the force coefficients. The cutting force components were observed to decrease as the percentage rice husk ash (RHA) reinforcement increased. This agrees with known results for the composite based on the dynamometric approach. Since the cutting force components decrease with increase in reinforcement, it can be deduced that increasing RHA in the Aluminium might reduce friction at the tool-chip interface and extend tool life, in other words, improving machinability. The composite therefore promises to be more cost effective than the base material in machinability terms.

Powder Injection Moulding and Liquid Phase Sintering of Aluminium - SiC Particulate Composite

Metal matrix composite has been increasingly appreciated by many engineering applications due it its tailored properties for specific uses. Powder injection moulding is one of the most effective composite processing essentially for small and complex parts. Moulding of feedstock is the key step determining green and sintered properties. This research investigated effects of moulding parameters which are % solid loading and moulding speed on microstructure and properties of aluminium composite. Commercial aluminium alloy powder and SiC particulate at 15 vol.% addition were formulated at 55 % and 60 % solid loading. Injection moulding were operated using a horizontal screw driven typed machine at 1600-1800 rpm speed and 280 - 300 °C moulding temperature. After sintering at 655 °C, property assessment via microstructure, density, % shrinkage, distortion and hardness were carried out. It was found that feedstock of 55 % solid loading occasionally led to flash problem while that of higher solid loading experienced higher viscosity to fulfill four-cavity mould. Moulding speed investigated did not significantly affect mould filling and overall properties. Sintered microstructures generally showed well-distributed SiC particulate in the aluminium matrix. The optimum injection moulding condition was the feedstock prepared at 60% solid loading, moulding at 1800 rpm speed, which offered theoretical density of greater than 98.5 % and micro Vickers hardness of 125.2 Hv.

On the Magnetoelectric Performance of Multiferroic Particulate Composite Materials

In the current work, quantitative analysis of magnetoelectric particulate composite material system explicated the main mechanisms responsible for the below-optimal performance of this class of materials. We considered compliant particulate composite materials, with constituents relevant to technological and scientific interest, leading to 0-3 Terfenol-D/PVDF-TrFE composite samples. To this objective, thick Terfenol-D/PVDF-TrFE films (10-15 µm) were fabricated and analyzed for chemical, mechanical, and magnetic properties to demonstrate their suitability for energy applications in harsh environmental conditions. The vigorous experimental characterization of the composite exemplified the multifunctional properties, quantifying the interrelationship between the composition and performance. We observed that the addition of magnetic particles to the electroactive copolymer matrix resulted in improvement in the mechanical and electrical properties since the particles acted as pinning sites, hindering the deformation of the chains and enhancing polarization. The effective modulus model was amended to account for the crystallization-induced change in material stiffness. We also measured and computed the magnetic particles motion to explicate the detrimental effect of mobility and migration on the overall magnetoelectric coupling performance of the composite. Thereby, we derived an analytical model based on the magnetic force due to the co-presence of alternating and constant magnetic fields, and the viscous drag force due to the viscoelastic properties of the electroactive copolymer matrix. We demonstrated that the mobility of the particles plays a crucial role in the short and long term performance of magnetoelectric coupling in multiferroic particulate composites, uncovering the underpinnings of the dichotomy in performance between experimentally measured and analytically predicted coupling coefficients., thus, allowing for the proposal of new approaches to realize the scientific potential of magnetoelectric particulate composites in energy applications.

Anisotropic imperfect interface in elastic particulate composite with initial stress

The model of an anisotropic interface in an elastic particulate composite with initial stress is developed as the first-order approximation of a transversely isotropic interphase between an isotropic matrix and spherical particles. The model involves eight independent parameters with a clear physical meaning and conventional dimensionality. This ensures its applicability at various length scales and flexibility in modeling the interfaces, characterized by the initial stress and discontinuity of the displacement and stress fields. The relevance of this model to the theory of material interfaces and its applicability in nanomechanics is discussed. The proposed imperfect interface model is incorporated in the unit cell model of a spherical particle composite with thermal stress owing to uniform temperature change. The rigorous solution to the model boundary value problem is obtained using the multipole expansion method. The reported accurate numerical data confirm the correctness of the developed theory, provide an estimate of its accuracy and applicability limits in the multiparticle environment, and reveal significant effects of the interphase or interface anisotropy and initial stress on the local fields and overall thermoelastic properties of the composite.

Mycelium-Based Composites as Two-Phase Particulate Composites: Compressive Behaviour of Anisotropic Designs.

Mycelium Based Composites (MBC) exhibit many properties that make them promising alternatives for less sustainable materials. However, there is no unified approach to their testing. We hypothesise that the two-phase particulate composite model and use of ASTM D1037 could provide a basis for systematisation. An experimental series of MBC were produced using four substrate particle sizes and subjected to compression testing. We report on their effect over Young’s modulus and ultimate strength. We extend the study by investigating three anistropic substrate designs through orientated fibre placement as a strategy for modifying compressive behaviour. We find that the two-phase particulate model is appropriate for describing the mechanical behaviour of MBC and that mechanical behaviour can be modified through anisotropic designs using orientated fibres. We also confirm that fibre orientation and particle size are significant parameters in determining ultimate strength.