Electrical Characterization of Traditional and Aerosol Jet Printed Conductors Under Tensile Strain

ABSTRACTIn this work, we propose a model to quantify strain induced conductor discontinuities based on measuring electrical resistance while applying tensile strain to metal-polymer systems. Under strain, changing conductor geometry and induced conductor discontinuity increase electrical resistance. On Kapton substrates strained to ε = .07, evaporated gold films did not deform and resistance increase was only caused by geometry change. Conversely, discontinuity caused 31% and 72% of the resistance increase in evaporated and printed silver films at the same strain. On PDMS substrates, the same magnitude of discontinuity, causing 31% of the resistance increase, occurred at only ε = .024 in evaporated silver films. At the same strain, discontinuity caused 86% of the resistance increase in evaporated gold films. Printed silver films were inelastic. The results suggest that traditional fabrication techniques may be more suitable to flexible hybrid electronics applications than additively manufactured conductors.

A Parametric Study on the Influence of Imperfections on Pipe Mechanical Response During Bending in Reel-Lay Installation Using Finite Element Method

Finite element modelling procedures were developed to examine the effect of pipe diameter, ovality, wall thickness, imperfection formulations, joint-to-joint material strength variation and radial weld offset on the pipe mechanical response through numerical simulation of the reeling process. This study examines the pipe deformation, stress concentration, and strain discontinuity developed during simulation of the pipe reeling process. The key parameters influencing the pipe mechanical response are identified and recommendations on future work provided.

Contact problem of an elastic plug in an elastic region

The contact problem investigated in this paper may be more fully described as a three dimensional elastic body with a circular hole through it; inside this tunnel is press fitted a solid elastic plug of finite length. Shear stresses are taken to be absent along the contact interface.An influence coefficient technique is used to model the governing integral equation. For the elastic region the displacement influence coefficients due to bands of constant pressure are determined using a numerical quadrature on Fourier integrals. However, the plug, being of finite length, requires the superposition of two separate solutions to boundary value problems before the displacement influence coefficients can be determined.Contact pressure distributions are presented for a sample of parameter variations and also for a case where hydrostatic pressure is present in the tunnel in the elastic region. Despite both components being elastic the imposition of a constant interference displacement along the interface still gives rise to the characteristic singularity in contact pressure at the edges of contact due to the strain discontinuity at these points.