It is during the oil crisis of the 1970s that automobile industry began searching for ways and means to reduce fuel consumption. And they stumbled on the reduction in the weight of the vehicle as the best method. It was then estimated that reduction in the weight of a medium-sized car, say by about 100 kg would lead to a saving of around 700 liters of fuel during its lifetime. Thus began the usage of aluminum alloys to replace steel. Usage of aluminum alloys in making the components of the suspension, the chassis, cylinder blocks and other engine components is also noticed to reduce the carbon emissions into the atmosphere.
The ongoing worldwide debate on climate change and the legislation required to put in place measures for tackling emissions has only further intensified the search for light metal alloys to replace high strength steel and polymer matrix composites. This obviously calls for “a rethinking and modification of structural concepts”, which is why a belief has emerged that ‘multi-material concept’ will influence the research for light metal development. Currently, the global research is focused more on alloys and composites of aluminum, magnesium and titanium for usage in automobile industry.

In this context, the first paper, “The Effect of Rare Earth Addition and Stirring on the Mechanical Properties of a Cast A356 Alloy”, by Bharat Bhushan, Balraj Singh, Deepak Suthar, Jyoti Menghani and Dimple V Shah, presents the findings of the experiment carried out to study the effect of rare earth elements on the microstructure and mechanical properties of aluminum alloy—A 356 with and without stirring. The authors have casted the alloy by adding 0%, 0.5 wt%, 1.5 wt% rare earth at varying stirring speeds of 0, 400 and 600 rpm. Based on the mechanical testing and metallographic examination of the specimens, the authors have concluded: one, addition of 0.5 wt% rare earth at a stirring speed of 400 rpm rendered the highest hardness value; two, addition of 0.5 wt% rare earth at a stirring speed of 600 rpm gave the greatest improvement in quality indexing of A356; three, 0.5 wt% rare earth addition at 400 rpm stirring speed gave optimum hardness, micro hardness and tensile strength; and four, microstructural analysis revealed that rare earth addition refined the grain size by reducing the dendrite size and produced more fibrous eutectic silicon phase.
As a part of global effort to minimize fossil fuel consumption and resulting search for alternate fuels, the next paper, “An Application to Detect Knock and Combustion Severity of Diesel Engine Working with Biodiesel (COME)-Additive Blends Using Cylinder Vibration Signature”, by P Venkateswara Rao and B V Appa Rao, examines the generic cause of cylinder vibration and knock in general of a four stroke single cylinder diesel engine that was run with biodiesel-triacetin additive blends as fuel. The authors have measured the vibrations generated by the engine during knock using DC-11FFT analyzer with accelerometer. They have compared the FFT output obtained at each load of the cylinder excitation frequencies with that of the frequencies of diesel as baseline. They have also analyzed the modes operandi of combustion generating the vibrations and the engine knock using time wave forms on the cylinder head and derived heat release rate curves. According to them, mass fractions of 70%, 75% and 80% are safe in the context of knocking on set for both biodiesel and diesel fuels with developed mean effective pressures in the rated speed range of the engine.

The next paper, “Mesoscopic Modeling of Density-Internal Energy Distribution Function for Convection Heat Transfer”, by D Arumuga Perumal, examines the heat transfer parameters and flow characteristics by changing Rayleigh number and porosity in the presence of a medium using lattice Boltzmann method at the representative elementary volume scale. The author has opined that the DIEDF methodology is a reliable numerical apparatus for examination of conviction heat transfer through permeable media. The author has also argued that the DIEDF—as an option to the continuum-based systems such as finite difference method, finite volume method and finite element method—holds good in porous media.

The last paper, “Process Control Through Measurement of Cp and Cpk of a Production Process”, by D R Prajapati, using process control—an admixture of statistics and engineering discipline that deals with architecture, mechanisms and algorithms for maintaining the output of a specific process within a desired range—has computed the process capability, process capability ratio and process capability indices pertaining to kick starter gear and found that 0.465% of kick starter gear is beyond the control limits, which obviously is a major concern for the industry.

GRK Murty
Consulting Editor