A hybrid integrated trunk and subscriber line interface
A two-chip hybrid integrated trunk and subscriber line interface has been fabricated for voice and data applications. This paper will discuss features including a programmable battery feed with lightning protection, battery-reversal signaling, 2-4 wire conversion, loop closure detection and power down capability.
A 90V switching regulator and lightning protector chip set
A switching regulator providing variable voltage to accommodate loop resistances from 0 to 2800 Ω with 1.5W power limit has been developed. A transformerless trunk and subscriber line interface which serves as a protection device to shunt 10A lightning pulses to ground will be described.
Damage initiation and propagation in composite shells subjected to impact
Abstract The paper investigates the impact-induced damage initiation and propagation for laminated composite shells under low-velocity impact. A three-dimensional eight-node non-conforming element is described to analyze interlaminar stress distribution, and progressive failure. The damage analysis is performed by using Tsai–Wu quadratic failure criterion, Tsai’s damage modes and an additional delamination formula at all Gaussian points. The damage modes considered are matrix cracking, fiber breakage and delamination. The progressive failure is expressed by reducing stiffness of the material at all failed Gaussian points. Special attention is centered on curved laminates. Impact energy threshold for the onset of damage and transient damage size are predicted for composite shells. The analyses of the flat and curved laminates are compared for discussing their different damage mechanism. In addition, the influence of the stacking sequence, the thickness and the radius of curvature on damage behavior of composite shells are studied.