Triaxial Hydrostatic Stress Divergence Modeling and Interface Yield Control
Interface yield under triaxial loading depends on spatial hydrostatic stress gradients, requiring localized stiffness matching and controlled triaxial pressure testing.
Dundurs Parameters
Meaning
Dimensionless elastic constants quantify the mismatch in stiffness and Poisson’s ratio between two contacting solid materials. Calculations of the dundurs parameters yield two scalar values that determine the distribution of stress at the interface of a bimaterial joint. These values govern the behavior of stresses near the edge of a contact zone.
Interface Mismatch
Elastic incompatibility across a bonded boundary dictates the level of shear stress generated by normal forces. The dundurs parameters express this incompatibility through equations that combine the shear modulus and Poisson’s ratio of both materials. When these coefficients are close to zero, stress distributions resemble those of a single homogeneous material.
Stress Singularity
Stress states near the tip of an interface crack can become unbounded when different materials are joined together under load. Through the dundurs parameters, engineers characterize the strength of this stress singularity to predict whether a crack will spread. High singularity values mean the joint cannot handle significant thermal cycles because of high localized strain fields, which threatens the operational lifespan of joined subassemblies in microelectronic devices.
Numerical Calculation
Input variables for structural finite element analysis of joined parts must include the elastic constants of each constituent material. Mechanics calculations use the dundurs parameters to pre-process material property combinations before run time. This calculation speeds up structural optimization.