Measurement of the Torque Demand for Jar opening and its Relationship with Anthropometric and Physiological Factors

9% of all available packaging are jars with steel lids. However some consumers have troubles with jar opening. The aim of the current research is the analysis of the exerting force onto the jar lids relating the torque input to the anthropometric and physiological characteristics of the consumers.
Material and In this study, we examine the force distributed on the fingers and the palm using a special tester consists of the force sensing resistors (FSR) sensors. This tester includes 19 sensors, 14 of which are installed on the fingers and 5 on the palm. Each sensor is connected to a driver via two wires and then to a computer by a USB port. A full jar with 1100g weight and 85mm lid outer diameter was used and the forces exerted by 20 participants including 10 male and 10 female students were recorded. Then Minitab 17 software was used and the mathematical relationship between the torque and anthropometric and physiological characteristics was investigated.
It was found that the force is mainly exerted by the index finger. The calculation of the torque based on the force measurements showed that the maximum torque applied by men was 10.63Nm and by women was 7.66Nm. Statistical F-test for the torque (response variable) at 0.05 significance level resulted in p-values equal to 0.011 and 0.008 for male and female participants, respectively. Therefore, it can be concluded that the measured values are statistically significant.
Statistical analysis revealed that the hand dimensions and the grip strength play the main roles in applying torque. Additionally, the results indicated that packaging conditions for the particular jar in this survey must be adjusted such that the consumers with the lowest physical ability (5.11 Nm torque) can open them.