i) Shock resistance: tumble test The durability against mechanical shocks (falling down, for example) was tested with a tumbling barrel from a fall height of 80 cm with a rotation frequency of 5 turns per minute (= 10 falls per minute). After every 10 turns (20 falls) and 25 turns (= 50 falls), each sample was checked on loose parts (like battery), on visible damage and on correct performance (calling a number, dialled with the keys and receiving a call). Scratches of the housing after the tumble test are reported and rated. All the models tested for shock resistance showed some scratches but no severe damage was found in any of the model. ii) Water resistance: rain test The GSM phone was switched on and connected to a network. A raining appliance with a minimum of three nozzles was used to give an even rain distribution.
The phone was lying horizontal on a grid 50 cm below the rain nozzles. Artificial rain of 5 mm/minute was applied for 5 minutes with the phone lying on the grid, followed immediately by a function check (making and receiving a call) on the wet phone. Three days later, while storing the phones in normal lab climate, again a function check (making and receiving a call) was done, and working of the charging function was checked. Except Sony Xperia L, all the other models were found functioning after drying and no damage in any part was found. In Sony Xperia L’s loudspeaker, the microphone was found distorted and not working even after drying.