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Asphalt pavements are prone to cracking in low-temperature environments, and microwave heating (MH) can heal the cracks effectively. This research mainly investigates the different MH effects on the self-healing properties of asphalt mixtures. With this objective, the three-point splitting test is conducted to generate the cracks. A microwave oven is employed to heat the samples, and a thermal camera measures the surface temperature. Results indicate that heating power and time show a positive linear correlation with healing efficiency, and the HI of the samples can reach over 80%. The HI of the samples decreases with the heating cycle, but the sample with reasonable power and time still has a HI higher than 70% after 5 cycles. The temperature peaks on thermal images indicate that uneven heating exists during heating, but the heating uniformity is within an acceptable range. The healing efficiency level (HEL) suggests that asphalt mixtures have very low inefficient healing behavior if the heating time is below 45 s, but HEL can reach 86.14% at 700 W after 60 s. Furthermore, although the HI of strength shows ideal results, the recovery of other crack parameters, including stiffness, fracture energy, flexible index, and crack resistance index, are not satisfactory. [ABSTRACT FROM AUTHOR]

Asphalt pavements are prone to cracking in low-temperature environments, and microwave heating (MH) can heal the cracks effectively. This research mainly investigates the different MH effects on the self-healing properties of asphalt mixtures. With this objective, the three-point splitting test is conducted to generate the cracks. A microwave oven is employed to heat the samples, and a thermal camera measures the surface temperature. Results indicate that heating power and time show a positive linear correlation with healing efficiency, and the HI of the samples can reach over 80%. The HI of the samples decreases with the heating cycle, but the sample with reasonable power and time still has a HI higher than 70% after 5 cycles. The temperature peaks on thermal images indicate that uneven heating exists during heating, but the heating uniformity is within an acceptable range. The healing efficiency level (HEL) suggests that asphalt mixtures have very low inefficient healing behavior if the heating time is below 45 s, but HEL can reach 86.14% at 700 W after 60 s. Furthermore, although the HI of strength shows ideal results, the recovery of other crack parameters, including stiffness, fracture energy, flexible index, and crack resistance index, are not satisfactory.

Surface Mounted Devices (SMDs) are widely used throughout microelectronics and power electronics. They mostly employ epoxy molding compound (EMC) based encapsulations. Thus, enhanced lifetime assessment methods are necessary. To understand the stress situation in SMDs at the end of the production cycle, an improved model approach for the curing of EMC is implemented within Finite Element Analysis (FEA) simulations. During production, e.g., in a Resin Transfer Molding (RTM) process, material properties are spatially varying due to different curing degrees. Hence, a mismatch of mechanical properties is present, which in return leads to internal stresses. The introduced model approach is an extension of the work of Gschwandl et al. (2017) and includes a stress-free deformation before vitrification, changing material properties during curing, as well as plastic deformations and visco-elastic effects. The implementation in numerical FEA simulations allows for a better understanding of arising residual stresses and helps optimize the production cycle of SMDs. • Determining curing-induced residual stresses in power packages via simulations in Abaqus requires incremental stress calculation. • The introduced sequential simulation approach can be used for any given temperature profile. • Curing-induced residual stresses can lead to plastic deformations in power packages. • Applying stepped temperature profiles can have a positive effect on the cycle time and residual stress situation in the manufacture of power packages. [ABSTRACT FROM AUTHOR]