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Micrometric grains of anisotropic morphology have been achieved by evaporation-induced self-assembly of silica nanoparticles. The roles of polymer concentration and its molecular weight in controlling the buckling behavior of drying droplets during assembly have been investigated. Buckled doughnut grains have been observed in the case of only silica colloid. Such buckling of the drying droplet could be arrested by attaching poly(ethylene glycol) on the silica surface. The nature of buckling in the case of only silica as well as modified silica colloids has been explained in terms of theory of homogeneous elastic shell under capillary pressure. However, it has been observed that colloids, modified by polymer with relatively large molecular weight, gives rise to buckyball-type grains at higher concentration and could not be explained by the above theory. It has been demonstrated that the shell formed during drying of colloidal droplet in the presence of polymer becomes inhomogeneous due to the presence of soft polymer rich zones on the shell that act as buckling centers, resulting in buckyball-type grains.

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Passive shock absorbers are designed for standard load condition. These give better vibration isolation performance only for the standard load condition. However, if the sprung mass is lesser than the standard mass, comfort and road holding ability is affected. It is demonstrated that sprung mass acceleration increases by 50%, when the vehicle mass varies by 100 kg. In order to obtain consistent damping performance from the shock absorber, it is essential to vary its stiffness and damping properties. In this article, a variable stiffness system is presented, which comprises of two helical springs and a variable fluid damper. Fluid damper intensity is changed in four discrete levels to achieve variable stiffness of the prototype. Numerical simulations have been performed with MATLAB Simscape and Simulink which have been with experimentation on a prototype. Furthermore, the numerical model of the prototype is used in design of real size shock absorber with variable stiffness and damping. Numerical simulation results on the real size model indicate that the peak acceleration will improve by 15% in comparison to the conventional passive solution, without significant deterioration of road holding ability. Arrangement of sensors and actuators for incorporating the system in a vehicle suspension has also been discussed.