Experimental Investigation of Illumination Performance of Hollow Light Pipe for Energy Consumption Reduction in Buildings

This work investigates the light illumination intensity, light transmission performance, light distribution on the floor, and daylight factor of vertical light hollow tubes at various incident elevation angles of a light source. The light tubes were made from commercial aluminum alloy sheets and commercial zinc alloy sheets to investigate internal illuminance for buildings and reducing the demand of electrical energy from artificial lighting. The vertical light tubes with a constant length of 0.5 m and diameters of 0.20, 0.25, and 0.30 m were designed in a testing room model, with dimensions of 1 m × 1 m × 1 m. A 20-W light-emitting diode (LED) lamp was used as the light source for the lighting simulations, which was placed away from the top of the light tube. The incident elevation angle of the light source was changed between 0° and 80° with 5° increments. It was found that the elevation angle of the incidence light had an influence on the light intensity distribution on both ends of light tube. The average illuminance performance of both material types increased with an increase of the incidence angle from 0° to 80° and an increase of the tube diameter from 0.20 m to 0.30 m. The commercial aluminum alloy tube promotes greater light transmission and daylight factor when compared with the commercial zinc alloy tube in each condition. This illuminance measurement demonstrates that the light tube could be included in the lighting systems of some deeper or windowless areas of buildings to decrease the demand of energy consumption in the lighting of buildings.

Effects of Temperature and Strain Rate on Commercial Aluminum Alloy AA5083

Superplastic forming, SPF is a special metalworking process that allows sheets of metal alloys such as aluminum to be stretched to lengths over ten times. Nowdays, only a few aluminium alloys can meet the specific requirement of SPF manufacturing process and not much data available to represent their mechanical behaviour. In order to deal with this issue, this research project is conducted to investigate the characteristics of commercial aluminum alloy, AA5083 when tested at different strain rates and temperatures. These parameters play a crucial roles in the design and manufacturing processes of military, automotive and aerospace structures. Equally, the effects must be considered in the constitutive model development to accurately capture the deformation behaviour of such materials. The specimens were prepared according to 12.5mm gauge length standard. The Uniaxial Tensile Tests were carried out at various strain rate from 4.167 x10-1s-1to 4.167 x10-5s-1over a wide temperature range from ambient to 95°C. The experimental data shows that increasing strain rate increases flow stress, while increasing temperature decrease flow stress. This is leads to important conclusion that material AA5083 exhibits strain rate and temperature sensitivite, and suit with the SPF operating condition.

Corrosion Behavior of Commercial Aluminum Alloy Processed by Equal Channel Angular Pressing

A commercial aluminum alloy was subjected to severe plastic deformation through equal channel angular pressing (ECAP). The alloy contains a low volume fraction ofα-AlFeSi located essentially at the grain boundaries. The corrosion behavior of the ECAP’ed alloy was investigated in NaCl solution using potentiodynamic polarization and immersion tests. The effects of scan rate and NaCl concentration on the alloy susceptibility to corrosion were also studied. The results obtained were compared with those of the nonpressed alloy. ECAP leads to an intensive grain refinement accompanied by an increased dislocation density. All electrochemical tests confirm that corrosion resistance of the alloy remarkably diminished with increasing the ECAP number of passes. This is presumably due to the breakdown of theα-AlFeSi after ECAP leading to higher number of galvanic cells and enhanced dissolution of the aluminum matrix.