weave, architecture, yarn crimp, and the various mechanisms of energy absorption of the fabric, discussed later. To briefly compare various commercial brands of fabrics, Zylon woven fabrics absorb nearly twice the energy per unit areal density specific energy absorbed SEA than both Kevlar and Spectra, when gripped on all four edges, and almost 12 times that of aluminum fuselage skin. The ballistic impact performance of PBO systems is substantially superior to Kevlar 29 systems and marginally better than Kevlar KM2 systems 4. It is reported in Ref. 5 that Spectra fibers are ten times stronger than steel. Previous review work includes a database of early ballistic fabric research by Cunniff 6, and the mechanisms influencing ballistic performance of woven fabrics by Cheeseman and Bogetti 7.

Ballistic Impact of Dry Woven Fabric Composites: A Review

Microelectromechanical systems (MEMS) technologies are evolving at a rapid rate with increasing activity in the design, fabrication, and commercialization of a wide variety of microscale systems and devices. The importance of accurate mechanical property measurement for successful design was realized early on in the development of this field. Consequently, there exist many different techniques to measure quantities such as the Young's modulus (E), yield strength (σ
 Y
 ), fracture strength (σ
 F
 ), residual stress (σ
 F
 ), and residual stress gradient (∇σ
 R
 ) of microscale structures and materials. We review and critically compare several of the important techniques including the microtension test, axisymmetric plate bend test, microbeam bend test, M-test, wafer curvature measurements, dynamic (resonant) tests, fabrication of passive strain sensors, and Raman spectroscopy. We discuss the characteristics of typical test structures, and the common sources of structure-related errors in measurement. A rational approach for the selection of test techniques for the design of microsystems is suggested.

A Critical Review of Microscale Mechanical Testing Methods Used in the Design of Microelectromechanical Systems

A finite element modeling is developed to simulate and visualize the discontinuous chip formation in the orthogonal cutting of 60 percent Cu-40 percent Zn brasses. A ductile fracture criterion expressed as a function of strain, strain rate and hydrostatic pressure is applied to the crack growth from the tool tip to the chip free surface in the segmentation of discontinuous chips. Chip shape and the inclination of fracture surface produced in computational machining are in good agreement with those in actual machining. The visualization of the computational machining processes clarifies the mechanism of discontinuous chip formation. The influences of chip segmentation upon the residual stress and strain in the machined layer are also clarified quantitatively.

Application of computational machining method to discontinuous chip formation

Finite element analysis has been used in roadside safety research for nearly three decades. Early applications used simple discreet-element special-purpose codes to predict gross deflections of guardrails and bridge rails in collisions with motor vehicles. More recently general purpose nonlinear explicit finite element programs have been integrated into the analysis and design of roadside safety hardware. This paper reviews the history of the use of finite element methods in roadside safety research and presents the current status of many of the vehicle, occupant and roadside hardware models that have been developed to date.

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The Use of Finite Element Analysis in Roadside Hardware Design

Shear wall systems are one of the most commonly used lateral-load resisting systems in high-rise buildings. Shear walls have very high in-plane stiffness and strength, which can be used to simultaneously resist large horizontal loads and support gravity loads, making them quite advantageous in many structural engineering applications. There are lots of literatures available to design and analyse the shear wall. However, the decision about the location of shear wall in multi-storey building is not much discussed in any literatures. In this paper, therefore, main focus is to determine the solution for shear wall location in multi-storey building based on its both elastic and elasto-plastic behaviours. An earthquake load is calculated and applied to a building of fifteen stories located in zone IV. Elastic and elasto-plastic analyses were performed using both STAAD Pro 2004 and SAP V 10.0.5 (2000) software packages. Shear forces, bending moment and story drift were computed in both the cases and location of shear wall was established based upon the above computations.

Gannavaram D. Vishakhadatta

Papers

Finite Element Modeling of