A new thermomechanical fracture analysis approach for 3D integration technology
In this study, the peridynamic framework is applied to model heat diffusion to derive peridynamic heat diffusion equations. A numerical scheme is put forward and implemented in order to establish the validity of these equations. Finally, an approach is developed for coupled solution of heat conduction and solid mechanics equations in the realm of peridynamics.
Peridynamic Theory for Thermomechanical Analysis
Thermomechanical modeling for interconnects and electronic packages is a difficult challenge, especially for material interfaces and films under 1 ¿m dimension. Understanding and prediction of their mechanical failure require the simulation of material behavior in the presence of multiple length scales. However, the classical continuum theory is not capable of predicting failure without a posterior analysis with an external crack growth criteria and treats the interfaces having zero thickness. A new nonlocal continuum theory referred to as peridynamic theory offers the ability to predict failure at these length scales. This study presents a new response function as part of the peridynamic theory to include thermal loading. After validating this response function by comparing against the displacement predictions in benchmark problems against those of finite element method, the peridynamic theory is used to predict damage initiation and propagation in regions having dissimilar materials due to thermomechanical loading.
Pharmacokinetics of amikacin and chloramphenicol in the aqueous humor of rabbits
Composite data describing ocular pharmacokinetics are unreliable because of intersubject variation. To address this problem, an animal model was developed in which multiple aqueous samples from single subjects were obtained. Following direct anterior chamber or intravenous administration of amikacin or chloramphenicol, pharmacokinetic analysis of drug concentrations in the serum and anterior chamber was performed by using a nonlinear least-squares regression program. The number of anterior chamber paracenteses performed did not alter the beta elimination rates or percent penetration into the anterior chamber. The aqueous humor and peripheral-compartment terminal slopes were identical. These data indicate that complete ocular concentration-time curves can be obtained without altering antibiotic pharmacokinetics. Following direct injection into the anterior chamber, the elimination rates for both antibiotics followed a one-compartment model, whereas those following intravenous administration best fit an open, first-order, two-compartment model. Following intravenous administration, the anterior chamber elimination rate constants for both drugs were equal to that of the serum and significantly longer than that following direct injection. The elimination rates of both drugs following direct injection were similar. Systemic administration resulted in drug levels in aqueous humor that persisted longer than those following direct injection. Chloramphenicol, a lipophilic compound, gave higher mean concentrations in aqueous humor than did amikacin. Our model provides a new approach which rigorously examines ocular pharmacokinetics and provides data which suggest that for selected compounds the parenteral route of administration is preferable.