Rate-Dependent Constitutive Model Development of PC/ABS Material

Handheld consumer electronic devices such as smartphones are prone to drop impact during the field use condition. The smartphones are typically characterized for their drop impact performance to meet certain reliability test requirements before they are released into the market as commercial products. During the product development cycle, finite element analysis comes in handy to help understand the mechanics of the device and the interplay of various inner components. Of interest is the stresses generated in the chemically-strengthened glass that is used as cover glass in majority of smart phones. In order to be able to predict the stresses accurately, it is important to characterize key materials in the device for their rate-dependent non-linear elastic-plastic constitutive behavior as the drop event involves different strain rates. Polycarbonate (PC) is commonly used as back cover and sometimes the inner chassis in the smart phones. A rate-dependent constitutive model is developed through rigorous material testing in this effort for a particular type of PC/ABS blend. A finite element model of the test sample is built and used to validate the constitutive model developed.