Karma bağlantılı kompozit plaklarda farklı sıcaklıklar etkisiyle oluşan gerilmelerin analizi

Öz

Bu çalışmada, karma bağlantı yapılarak birleştirilmiş iki kompozit plakada uygulanan farklı uniform sıcaklıklar etkisiyle meydana gelen gerilmeler analiz edilmiştir. Karma bağlantı, pim ve yapıştırıcının birlikte kullanılması ile meydana getirilmiştir. Analizde sonlu elemanlar metodu (SEM) kullanılmıştır. Modelleme üç boyutlu olarak yapılmıştır. Modelleme ve çözümde, sonlu elemanlar yazılımı olan ANSYS programından yararlanılmıştır. Oluşturulan modele hem çekme yükü hem de uniform sıcaklık yükü aynı anda uygulanmıştır. Sıcaklığın gerilmeler üzerine etkisini gözlemlemek için çekme yükü sabit tutulmuş fakat 50, 70, 90 ve 110 oC’lik üniform sıcaklıklar uygulanmıştır. Elde edilen analiz sonuçlarına göre gerilmeler delik çevresinde yoğunlaşmıştır. Dolayısıyla, karma bağlantı üzerinde başlayacak bir hasarın delik çevresinden başlayacağı anlaşılmıştır. Gerilmelerin değeri, üniform sıcaklık artışındaki miktara bağlı olarak artmaktadır.

Anahtar Kelimeler

• Karma bağlantı, Gerilme analizi, SEM, ANSYS, Kompozit.

Analysis of stresses created effect of different temperature in hybrid bonded composite plates

Abstract

Mechanical properties of glass-fiber composite materials make them attractive for structural applications where high strength-to-weight and stiffness-to-weight ratios are required. Bolts, pins or rivets have been used extensively in these applications for transferring load between the structural components (Wu and Hahn, 1997). Among the different techniques for joining structural members, mechanical fastening through a pin is a common choice owing to low cost, simplicity, and facilitation of disassembly for repair (Scalea, Cappello and Cloud, 1999). Contrary to many metallic structural members, for which the strength of the joints is mainly governed by the shear and tensile strengths of the pins, composite joints present specific failure modes because of their heterogeneity and anisotropy (Pierron, Cerisier and Grediac, 2000).Adhesive bonding technology is commonly used these days in almost all the industries fields of the world and this is mainly because of its high strength-weight ratio, low cost and high efficiency (You et al., 2007). Nonetheless, the design of safe and cost effective bonded joints is a main challenge. It forces on the engineer to have a good understanding of the effect of material and geometric parameters on the joint’s strength (Derewonko et al., in press). In fact, the adhesive joints experience not only mechanical loads but also thermal loads. Because the adhesive joints consist of materials with different mechanical and thermal properties, the thermal strains in the joint members might cause serious stresses (Apalak and Gunes, 2002). According to literature survey, many researchers have studied either adhesively bonded or pinned single lap joint, double lap joint etc. But, the analysis of hybrid joints designed using both adhesively bonded and pinned single lap joints under both thermal loads and tensile loads has not been analyzed up till now, according to authors’ knowledge. Therefore, in this study stresses created different uniform temperatures effect in two composite plates bonded together with hybrid joint were analyzed. The hybrid joint was created using both pin and adhesive with together. In analysis, the finite element method (FEM) was used. Modeling and solutions were done as three dimensional FEM. During both modeling and solution processes, it was utilized from ANSYS software which is a perfect finite element code. It is known that, the hole is needed if the pin, bolt, rivet etc. are used in the structure for mechanical joint. Therefore, mesh structure is very important around the hole zone for FEM analysis because of stress concentrations. Nonetheless, the generation of mapped mesh is very difficult if the model has hole. However, in this study, the mapped mesh was provided by the author. Both tensile and uniform temperature loads were applied on created model with together. To observe the effect of temperatures on stresses tensile load is applied as single value when selected constant uniform temperature values were performed as 50, 70, 90 ve 110 oC. According to obtained analysis results, it was shown that thermal stresses were concentrated around the pin hole. Therefore, it is understood that any failure may be start from pin hole zone firstly. The magnitudes of stresses were increased by increasing uniform temperature, because the differences of mechanical properties between adhesive and composite adherents cause this result. The thermal expansion coefficient is very important in this increasing, particularly.

Keywords

• Hybrid joint, Stress analysis, FEM, ANSYS, Composite.