Alüminyum Plakaların Balistik Performansının Araştırılması

Konferans Bildirisi -- Teorik ve Uygulamalı Mekanik Türk Milli Komitesi, 2015Conference Paper -- Theoretical and Applied Mechanical Turkish National Committee, 2015Metal bilimcilerin geniş araştırma ve çalışmaları sonucu alüminyum alaşımı levhalar düşük yoğunluk, yüksek yapısal mukavemet ve enerji emiş kapasitesi özellikleri nedeniyle uçak yapıları, gemi, bina ve köprü gibi çok çeşitli uygulamaların yanında hafif korunma sistemlerinde de sıklıkla kullanılmaktadır. Bu çalışmada, Alüminyum plakaların balistik performansının araştırılması yapılmıştır. Yapıda kullanılan plakalar 10 mm kalınlığında ve 50x50mm boyutunda 2024-T3 alüminyum alaşımıdır. Alüminyum plakaların plaka açısı ve plaka kalınlığı değiştirilerek v=750 m/s hızda gönderilen FSP (Parçacık Benzetimli Mermiler) mermiye karşı optimum değerleri hesaplanmaya çalışılmıştır. Ayrıca 10 mm plaka ve merminin normalle yaptığı açı ? = 0º, 30º, 45º ve 60º olacak şekilde Lambert-Jonas yaklaşımına göre balistik limit hızı tespit edilmiştir. Anahtar Kelimeler: Alüminyum Alaşımlar, Balistik Test, Balistik limit, Açılı DarbeAs a result of extensive research and studies of metallurgists, aluminum plates are frequently used in a wide variety of applications including aircraft structures, ships, bridges, and buildings, in addition to light protection systems because of the characteristics of low density, high structural strength and energy absorption capacity. The aim of this study was to investigate the ballistic performance of aluminum plates. 10-mm thick and 50x50mm sized 2024-T3 aluminum plates were used in structures. The plate angle and plate thickness of aluminum plates were changed and optimum values were investigated subject to the FSP (Fragment Simulating Projectile) projectile sent with a velocity of 750 m/s. Furthermore, ballistic limit velocity according to Lambert-Jonas approach was identified in such a way that the angle which 10 mm plate and projectile make with the normal would be ? = 0°, 30°, 45° and 60°. Key Words: Aluminum Alloys, Ballistic Test, Ballistic Limit, Oblique Impac

Elastic stresses in an adhesively-bonded functionally-graded tubular single-lap joint in tension

In this study, the elastic stress analysis of an adhesively-bonded tubular lap joint with functionally-graded Ni-Al2O3 adherends in tension was carried out using a 3D 8-node isoparametric multilayered finite element with 3 degrees-of-freedom at each node. Stress concentrations were observed along the edges of both outer and inner tubes in the overlap region. Thus, the outer tube region near the free edge of the inner tube and the inner tube region near the free edge of the outer tube experienced considerable stress concentrations. Normal sigma(zz) and shear sigma(rz) stresses were dominant among the stress components. In addition, both edges of the adhesive layer experience stress concentrations, and the von Mises sigma(eqv) Stress decreases uniformly across the adhesive thickness at the free edge of the outer tube, whereas it increases at the free edge of the inner tube. However, different compositional gradients had only a small effect on the through-the-thickness normal and shear stress profiles of both outer and inner tubes, and the peak von Mises sigma(eqv) stresses occurred inside the tube walls. As the ceramic phase in the material composition of the outer and inner tubes was increased, peak von Mises sigma(eqv) stress appeared in the ceramic layer. However, its magnitude was increased 1.75-fold in both tubes. In addition, the peak adhesive stresses appeared at the edge of the outer tube-adhesive interface near the free edge of the inner tube and at the edge of the inner tube-adhesive interface near the free edge of the outer tube. Increasing the ceramic phase in the material composition caused 1.22-1.67-times higher von Mises stresses along the free edges of the adhesive-tube interfaces. In addition, with increasing number of layers across the inner and outer tubes the profiles of the normal sigma(zz), shear sigma(r theta) and von Mises sigma(eqv) stresses across the tube walls and adhesive layer become similar. Increasing the ceramic phase in the material composition of the tubes causes also evident increases in the normal sigma(zz) and von Mises stresses while it does not affect their through-the-thickness profiles. However, it affects only shear sigma(r theta) and von Mises stresses across the adhesive layer. Finally, the layer number and the compositional gradient do not affect considerably through-the-thickness normal and shear stress profiles but levels in a functionally graded plate subjected to structural loads

Geometrically non-linear analysis of adhesively bonded modified double containment corner joints - II

In this study, the geometrical non-linear analysis of an adhesively bonded modified double containment corner joint, which is presented as an alternative to previous corner joints, was carried out using the incremental finite element method based on the small strain-large displacement (SSLD) theory. The analysis method assumes the joint members such as the support, plates, and adhesive layers to have linear elastic properties. Since the adhesive accumulations (spew fillets) around the adhesive free ends have an important effect on the peak adhesive stresses, their presence was taken into account by idealizing them as triangular in shape. The joint was analysed for two different loading conditions: one load normal to the horizontal plate plane, P-y, and one load horizontal at the horizontal plate free edge, P-x. Finally, small strain-small displacement (SSSD) analysis of the joint was carried out and the results of both analyses were compared in order to determine the capability of the two theories in predicting the effects of large displacements on the stress and deformation states in the joint members. Both analyses showed that the peak stress values appeared at the slot corners inside the adhesive fillets and at the upper and lower-longitudinal fibres (top and bottom longitudinal surfaces) of the horizontal and Vertical plates corresponding to the horizontal and vertical slot free ends. In the case of the load P-y, the right vertical adhesive fillet and both plates were the most critical joint regions, whereas the lower horizontal fillet and both plates were determined to be the most critical regions for the load P-x. The SSLD theory predicted a non-linear effect on the variations of the displacement and stress components at these critical adhesive and plate locations for the load P-x, whereas the stress components at the critical adhesive locations presented variations very close to those determined by the SSSD theory for the load P-y, but this non-linear effect appeared on the displacement and stress variations at the critical locations of both plates. In addition, the SSSD theory predicted that the displacement and stress components would have lower variations proportional to the increasing load for both loading conditions. The stress and deformation states of all joint members are strictly dependent on the boundary and loading conditions. In addition, whereas the SSSD theory may be misleading for some loading conditions, the SSLD theory gives more realistic results, since it takes into account the non-linear effect of large displacements and rotations