The weld strength of thermoplastics with aluminium alloy, such as high density polyethylene and polypropylene sheets, is influenced by friction stir welding parameters. This paper focuses on the preliminary investigation of joining parameter at various levels as well as the mechanical properties of friction spot joining (FSJ) of aluminium alloy (A5052) to polyethylene terephthalate (PET). A number of FSJ experiments were carried out to obtain optimum mechanical properties by adjusting the plunge speed and plunge depth in the ranges of 5-40 mm min 21 and 0?4-0?7 mm respectively, while spindle speed remains constant at 3000 rev min 21 . The results indicated that A5052 and PET successfully joined with the aid of frictional heat energy originated from the friction spot welding process. The effect of plunge speed on the joined area and the effect of formation of bubbles at the interface of joints on the shear strength of joint are discussed.

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Abstract:Overall fatigue strengths and hardness distributions of the aluminum alloy similar and dissimilar friction stir welding (FSW) joints were determined. The local fatigue strengths as well as local tensile strengths were also obtained by using small round bar specimens extracted from specific locations, such as the stir zone, heat affected zone, and base metal. It was found from the results that fatigue fracture of the FSW joint plate specimen occurred at the location of the lowest local fatigue strength as well as the lowest hardness, regardless of microstructural evolution. To estimate the fatigue strengths of aluminum alloy FSW joints from the hardness measurements, the relationship between fatigue strength and hardness for aluminum alloys was investigated based on the present experimental results and the available wide range of data from the references. It was found as: σ a (R = −1) = 1.68 HV (σ a is in MPa and HV has no unit). It was also confirmed that the estimated fatigue strengths were in good agreement with the experimental results for aluminum alloy FSW joints.

We report refraction-type non-mechanical beam steering using a 100-μm-thick swelling liquid crystal gel film with a polymer concentration gradient, in which an electrically-induced, large refractive index gradient along the uniaxial direction causes the deviation of a laser beam incident perpendicularly to the LC gel film. The swelling LC gel film is fabricated by polymerizing a LC-monomer/LC mixture while cooling it at a low temperature of -20 °C, and exhibits a short decay response time on the order of tens of microseconds. Thus, our device demonstrates non-mechanical beam steering with scan rate greater than 1 kHz.

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