Mechanical and Micrography Analysis of Armour Plate Weldment Using Tungsten Inert Gas and Oxy-Acetylene Welding Methods

Defence Industries Corporation of Nigeria (DICON) has compared the effect of Tungsten Inert Gas (TIG) and Oxy-Acetylene welding methods on microstructural and some mechanical properties of Armour plate for the modification of military troop carriers. The optical emission spectrometer (OES) at DICON was used to analyse the chemical composition of the armour plate strip. It was then machined and cut to various test piece dimensions for both welding processes, following which the weldment samples were subjected to post-weld mechanical tests (tensile, impact, and hardness) and metallographic examination. The samples were then welded according to the procedure outlined in this study. The fundamental composition of armour plates was preserved in the samples. When compared to Oxy-Acetylene (OA) welding, Tungsten Inert Gas (TIG) welding produced better results, with an average ultimate strength (UTS) of 603.52 MPa and an impact strength of 10.53 J. In addition, the TIG analysis hardness strength for the source material, heat affected zone (HAZ), and weldment sample is 510.3, 502, and 511-HV, respectively. At x200 magnification, the micrography of the TIG weldment revealed a small coarse grain size of ferrite and larger areas of pearlite.

Forecasting the Microstructure of a Microalloyed Steel Plate Strip

A description of the experience in the development and implementation of a model for forecasting the microstructure of rolled tubular products steel during thermomechanical processing of a semi-finished product and the relative IT-solution for the plate mill 5000 of PJSC MMK is presented. This solution is based on modeling the kinetics of structure formation in the mill technological line. The article describes briefly the result of analysis of a number of existing kinetics models of phase and structural transformations from the point of view of their application under the conditions of interest to us. An empirical study of the thermal effects of phase transformations and the influence of the heat removal mode on the kinetics of structure formation is described. The process of development of an empirical kinetics model and implementation of IT-solution, that implements this model, is also described.

Shear actuation-based hybrid damping treatment of sandwich structures using a graphite particle-filled viscoelastic layer

In this work, the effectiveness of a shear actuation-based hybrid active-passive damping treatment is investigated by incorporating the inclusion of graphite particles within the viscoelastic damping layer. The study is performed through the flexural vibration analysis of a sandwich plate-strip where the core is made of a laminate of active layers and graphite particle-filled viscoelastic layers in two different stacking sequences. The active layers are comprised of shear mode piezoelectric actuator patches that are activated according to a shear-based velocity feedback control strategy. The analysis is performed by deriving a closed-loop finite element model of the sandwich plate-strip, and it reveals that the hybrid damping is significantly dependent on the stacking sequence of active and passive damping layers at the core. The inclusion of graphite particles not only provides augmented passive damping but also causes enhanced transfer of shear actuation force from the active layers to other layers. As a result, a significantly improved shear actuation-based hybrid active-passive damping is achieved due to the inclusion. The effectiveness of this hybrid damping in attenuation of resonant displacement-amplitude is also presented by configuring the volume fraction of graphite particles and shear actuator patches in an optimal manner.

Flexure of a rigidly clamped orthotropic sandwich plate strip – An elasticity solution using superposition method

A simple two-dimensional elasticity solution is presented here for flexure of an infinite sandwich strip with rigidly clamped ends; it is based on the superposition of a strong form solution for a simply supported strip under transverse loading and a Ritz solution for end-loading. Results useful for future comparisons are presented in tabular form. On the basis of these results, the accuracy of classical plate theory and first-order shear deformation theory is critically examined. Finally, the difference between rigidly clamped end conditions and a softer version of clamped conditions is highlighted with reference to far-field response.

Analytical, FEM-numerical and experimental studies of bending of a sandwich plate-strip with metal foam core

Przedmiotem badań jest trójwarstwowe pasmo płytowe poddane czteropunktowemu zginaniu. Opracowano analityczny model tego pasma, korzystając z klasycznej teorii linii łamanej nazywanej teorią Zig-Zag. W paśmie tym wyróżniono trzy przedziały: dwa brzegowe, w których występuje zginanie i ścinanie oraz jeden środkowy, w którym występuje czyste zginanie. Wyznaczono całkowite ugięcie maksymalne pasma płytowego oraz maksymalne ugięcie odcinka środkowego. Przeprowadzono obliczenia numeryczne metodą elementów skończonych (MES) dla takiego samego modelu pasma, jak wyżej wspomniany model analityczny. Próbę doświadczalną przeprowadzono na stanowisku badawczym w Instytucie Pojazdów Szynowych. Porównano wyniki badań analitycznych, numerycznych i doświadczalnych. Analizowane płyty warstwowe mogą być stosowane, m. in. jako części podłogi lub poszycia pojazdu szynowego.

On the Modeling of Periodic Sandwich Structures with the Use of the Broken Line Hypothesis

In this paper a dynamic analysis of sandwich plate with a certain periodic microstructure is considered. The initial system of governing equations is derived basing on the classic broken line hypothesis. As a result of transformations one can obtain a system of three differential equations of motion with periodic, highly oscillating and non-continuous coefficients. In order to derive a system of equations with constant coefficients tolerance averaging technique is applied. Eventually, in the calculation example a free vibration analysis of certain periodic plate strip is performed with the use of both the derived model and a FEM model. It can be observed that the consistency of obtained results is highly dependent on the calculation assumptions.

Static and Dynamic Analyses of Nanocomposite Plates in Mechanical and Aerodynamic Loading

In this paper, flutter and divergence instabilities of functionally graded porous plate strip reinforced with graphene nanoplatelets in supersonic flow and subjected to an axial loading are studied. The graphene nanoplatelets are distributed in the matrix either uniformly or non-uniformly along the thickness direction. Four graphene nanoplatelets distribution patterns namely, Patterns A through D are considered. Based on the modified Halpin–Tsai micromechanics model and the rule of mixture, the effective material properties of functionally graded plate strip reinforced with graphene nanoplatelets are obtained. The aerodynamic pressure is considered in accordance with the quasi-steady supersonic piston theory. To transform the governing equations of motion to a general eigenvalue problem, the Galerkin method is employed. The flutter aerodynamic pressure and stability boundaries are determined by solving standard complex eigenvalue problem. The effects of graphene nanoplatelets distributions, graphene nanoplatelets weight fraction, geometry of graphene nanoplatelets, porosity coefficient and porosity distributions on the flutter and divergence instabilities of the system are studied. The results show that the plate strip with symmetric distribution pattern (stiffness in the surface areas) and GPLs pattern A predict the highest stable area. The flutter and divergence regions decrease as the porosity coefficient increases. Besides, the critical aerodynamic loads increase by adding a small amount of GPL to the matrix.

Material-Oriented Shape Functions for FGM Plate Finite Element Formulation

A four-noded finite element of a moderately thick plate made of functionally graded material (FGM) is presented. The base element is rectangular and can be extended to any shape using a transformation based on NURBS functions. The proposed 2D shape functions are consistent with the physical interpretation and describe the states of element displacement caused by unit displacements of nodes. These functions depend on the FGM’s material parameters and are called material-oriented. The shape function matrix is based on a superposition displacement field of two plate strips with 1D exact shape functions. A characteristic feature of the proposed formulation is full coupling of the membrane and bending states in the plate. The analytical form of the stiffness matrix and the nodal load vector was obtained, which leads to the numerical efficiency of the formulation. The element has been incorporated into Abaqus software with the use of Maple program. The finite element shows good convergence properties for different FGM models in the transverse direction to the middle plane of the plate. During derivation of the 2D plate element the formally exact 1D finite element for transverse nonhomogeneous FGM plate strip was developed.