Contact pressure distribution characteristics of Korla pear fruit at moment of drop impact

In order to understand the impact damage mechanism of Korla pear fruit, the contact pressure characteristics of Korla pear impacts against four counterfaces at varied drop heights were measured using prescale? pressure sensitive film, the distribution was analyzed and then the relationship between bruising area of Korla pare fruit and contact pressure distributions was determined. The results showed that the peak of contact pressure was 0.5-0.6 MPa for Korla pear impacting against four counterfaces. For Korla pears against steel and plywood surfaces, the pressures tended to a normal distribution with relative small pressure area which approximated to bruising area. Additional, the 0.2-0.3 MPa pressure covered largest area and the average pressure was 0.25-0.28 MPa. In the case of pear dropping onto expanded polyethylene (EPE) and corrugated board at low impact level, the pressures did not conformed to normal distribution and the pressure area was much larger than bruise area of pear. Also, it was founded that the pressure below 0.2 MPa was in larger area and the average pressure was 0.18-0.25 MPa for pear contacts with these cushion materials. With the increasing of the impact level, the pressure area increased linearly. The average pressure changed insignificantly for pear dropped onto rigid materials but tended to increase for impacts against cushion materials when impact level was increased. The linear regress models fitted by the production of pressure area and average pressure can exactly predicate and assess Korla pear bruise area. It provides a reference for designing the mechanized and automated equipment to reduce likelihood of pear bruising occurring.