Amir Javidinejad

Design and structural testing of smart composite structures with embedded conductive thermoplastic film

The ongoing research and development of cost effective technology for remotely queried sensors for health and usage monitoring of composite structures has lead to the application of electrically conductive thermoplastic adhesive films. This paper intends to provide an in depth overview of a newly developed technology for the design and manufacturing of smart structures by introducing the application of electrically conductive thermoplastic adhesive films. The current technology is discussed and compared with this newly developed technology. It is shown that the structural aspects of this new technology are advantageous to the concept of smart structures as a whole. Fabrication and manufacturing techniques for this new technology is discussed, including the suitability of the process for automation. Specifically, standard tensile testing of the manufactured composite coupons with embedded thermoplastic conductive adhesive films have performed and compared to the test results from copper embedded coupons. The effect of embedded thermoplastic stripes on stiffness as well as strength of the parent laminated structure is evaluated and discussed. Furthermore, fatigue testing was performed at various ultimate failure strength percentiles to determine some degree of the fatigue life of the composite and the embedded conductive and insulting films. The conductive thermoplastic films are found to be structurally superior to copper when embedded in a composite structure, but the electrical conductivity is not as good as copper or other metallic conductors.

BUCKLING OF BEAMS AND COLUMNS UNDER COMBINED AXIAL AND HORIZONTAL LOADING WITH VARIOUS AXIAL LOADING APPLICATION LOCATIONS

Abstract In this paper the buckling behaviour of an I-beam under combined axial and horizontal side loading is examined. It is to shown that the actual application location of the axial loading governs the buck- ling behaviour of the long I-beam. Theoretical formulation is developed to determine the critical buckling load for such combined loading configura- tion from the elastic static theory. Both, the beam deflection theoretical model and the critical load capacity are derived for this combined loading condition. The Finite Element Analysis (FEA) is utilized to apply the axial load on the beam at various configuration locations and it is shown that this application location determines the buckling behaviour and the critical load of the buckling of the I-beam. Numerical example is given.

Vibration Modal Solutions Developing of the Elastic Circular Membrane in Polar Coordinates Based on the Fourier-Bessel Series

Abstract This paper is written to show the development of the vibra- tion modal solutions of elastic circular membranes in polar coordinates us- ing the Fourier-Bessel series. The ordinary differential equation approach is utilized and the Laplacian of wave equation in polar coordinates is used to develop the solution of the membrane vibrations. A Fourier-Bessel so- lution is developed for the vibration of the elastic circular membrane in specific separation of variables is elaborated and based on the initial and boundary conditions. A numerical example is provided to show the ap- plication of such theory.

Full Length Symmetric Versus Partial Length Un-symmetric Pin Loading Failure and Analysis for Clevis Attachments

In this paper, testing failure of the clevis–pin attachments for full length symmetric versus partial length un-symmetric configuration is considered. Theoretically and analytically it can be shown that due to higher stress levels in the partial length un-symmetric pin clevis configuration failure occurs sooner than in a full length symmetric pin clevis configuration. However, here by placement of the two different configurations at opposite ends of one axial tensile test setup the theory was put in test. The test results also indicated that the partial length clevis–pin attachment fails sooner than the full length clevis–pin attachment. Experimental procedures are described here in this paper. Both theoretical and finite element analyses are performed to validate the failure.

Application of anisotropic thin plate theory for development of displacements for silicon crystals plates in cylindrical systems

Abstract Silicon <111> crystal is one of the crystal orientations, which shows potential for application in micro device developments of pressure diaphragms for measurement purposes. To date, no theoretical basis has been examined to develop the deflections for computational analysis purposes [1]. This paper presents the development of the diaphragm deflections for Silicon <111> Crystal in Cylindrical coordinates system. The Silicon <111> crystal possesses transverse isotropic properties. Thus, an anisotropic thin plate theory is used here to develop the plate deflection. A numerical example is given to compare the theoretical results with Finite Element Analysis (FEA) results.

Embedding of MEMS pressure and temperature sensors in carbon fiber composites: a manufacturing approach

In this paper embedding of surface mount pressure and temperature sensors in the Carbon fiber composites are described. A commercially available surface mount pressure and temperature sensor are used for embedding in a composite lay- up of IM6/HST-7, IM6/3501 and AS4/E7T1-2 prepregs. The fabrication techniques developed here are the focus of this paper and provide for a successful embedding procedure of pressure sensors in fibrous composites. The techniques for positioning and insulating, the sensor and the lead wires, from the conductive carbon prepregs are described and illustrated. Procedural techniques are developed and discussed for isolating the sensors flow-opening, from the exposure to the prepreg epoxy flow and exposure to the fibrous particles, during the autoclave curing of the composite laminate. The effects of the autoclave cycle (if any) on the operation of the embedded pressure sensor are discussed.