Abstract
This paper has studied factors that affect consumers' feeling in fingers when unscrewing the cap to open an aluminum beverage bottle, and then investigated experimentally and numerically the size of the cap in order to guarantee consumers' openability. At first, the gripping and opening way while rotating the cap by fingers has been determined as the most popular opening way according to a survey of consumers. The grip force and torque have been then measured simultaneously using an experimental bottle equipped with force sensors, and the relationships between the gripping force of fingers and the torque, the dimension and the gripping force of human hands have been investigated.
