Bending response of hybrid composite tubular beams

The influence of inner and outer reinforcements on the bending performance of a thin walled aluminum tube was investigated. Polymeric materials (PA6, PP) and glass/carbon fiber reinforced epoxy were considered to form the composite beam for the inner and outer reinforcement, respectively. The experimental results indicated that the outer reinforcement with a [0(2)/90(3)] fiber orientation layout increased the collapse load by a factor of 4.5 and 5.3. In the hybrid composite beam (HCB), load carrying capacity (LCC) increased a maximum of 14 times. Load carrying capacity of HCB is 2.5 times higher than the steel tube that is used in automotive industry. (C) 2013 Elsevier Ltd. All rights reserved

Comparison of Mechanical Properties of Unidirectional and Woven Carbon, Glass and Aramid Fiber Reinforced Epoxy Composites

In this study, mechanical behavior of epoxy composite reinforced by unidirectional and woven fiber is investigated experimentally. In the preparation of composite samples woven shaped glass, aramid and carbon fibers and unidirectional shaped glass and carbon fibers were used. Tension, compression and shear tests were carried out to determine mechanical properties of composites. It is seen from the test results, that unidirectional carbon fiber shows better performance than the glass fiber. Mechanical properties of 0 degrees-oriented unidirectional fiber are better than those of 90 degrees-oriented unidirectional fiber. Mechanical properties of aramid-fiber-reinforced composite are higher than those of glass and carbon fiber, when the woven types of fibers are considered

FE simulation of plastic collapse and geometrical factors affecting the bending response of a tubular aluminum beam

In this study, bending response of circular aluminum tube and factors affecting collapse behaviour were investigated by FE simulations. Geometrical parameters such as wall tube thickness, tube diameter, support distances, punch diameter and material properties were considered in analyses systematically. The results of analyses revealed that local buckling plays an important role on collapse load and buckling displacement is directly proportional to tube diameter, regardless of D/t and yield strength of tube material. The ratio of buckling displacement to tube diameter corresponds to 40 % of tube diameter. Moreover, an attempt was made to construct an equation as a function of D, t and yield strength for estimating collapse load. Finally, ANOVA test was used to analyze the influence of some parameters such as diameter of tube, wall thickness and yield strength. It is found from the test that the most significant factor on maximum load is wall thickness (79.6 %)

Three Point Bending Behavior of Woven Glass, Aramid and Carbon Fiber Reinforced Hybrid Composite Tube

In this study, bending behavior of hybrid composites reinforced by different type of fibers is investigated experimentally. In the preparation of composite samples with different number of layers having the same thickness and woven shaped glass, aramid and carbon fibers are used and three-point bending test is carried out to determine bending behavior. It is seen from the test results that, regardless of fiber type, the load bearing capacity and energy absorption capability are increased by increasing layer number. As a result of evaluation of hybrid composites containing different fibers with respect of load-carrying capability and energy absorbing capacity, aramid-fiber reinforced composite with 2 and 4 layer provides better performance. T + 2GF + 2CF + 2AF specimen can be preferred in between 10 layered hybrid tubes and T + 2GF + 2AF + 6CF and T + 2GF + 2CF + 6AF specimens in 10 layered hybrid tubes. Load carrying capacity of hybrid tubes increased 7 times and energy absorbing capacity 9.6 times, respectively

Bending and lateral crushing behavior of a GFRP and PA6 reinforced aluminum square tube

In this study, the bending behavior of a thin-walled aluminum square tube (AST) were analyzed using the finite element (FE) method, and reinforcing arrangements were decided for the composite beams based on the FE results. Accordingly, bending behavior of thin-walled ASTs with internal cast polyamide (PA6) and external glass fiber reinforcement polymers (GFRP) were investigated via a quasi static three-point bending test experimentally. Moreover, bending performance under impact loading was also investigated experimentally. The results revealed that local buckling has a decisive influence on bending performance of the tube, and the contribution of inner reinforcement is more effective than outer reinforcement. The reinforcements provide 575 % and 312 % increases in bending load and impact energy, respectively. The developed plastic-metal hybrid-composite structure is promising especially for critical supporting parts in vehicles. It is thought that the combination of these materials will offer new focus of attention for designers seeking more appropriate composite beams with high bending load and impact resistance

Numerical investigation on stress concentration of corrosion pit

Localized (pitting) corrosion has been observed in steel and high-strength aluminium alloys in aqueous environments and has been identified as a potential origin for fatigue crack nucleation. In the present study, under uniaxial tension loading, stress distribution at the semi-elliptical corrosion pits has been investigated by conducting a series of three-dimensional semi-elliptical pitted models, systematically. Based on the finite element analyses, it is concluded that pit aspect ratio (a/2c) is a main parameter affecting stress concentration factor (SCF). An attempt has been made to construct simple equations to SCIF depending on characteristic of pit parameters. At the bottom of hemispherical pit, contribution of secondary (premature) pit formation to SCF is very pronounced. (C) 2009 Elsevier Ltd. All rights reserved

Buckling behavior of fiber reinforced plastic-metal hybrid-composite beam

It is known that the buckling is characterized by a sudden failure of a structural member subjected to high compressive load. In this study, the buckling behavior of the aluminum tubular beam (ATB) was analyzed using finite element (FE) method, and the reinforcing arrangements as well as its combinations were decided for the composite beams based on the FE results. Buckling and bending behaviors of thin-walled ATBs with internal cast polyamide (PA6) and external glass and carbon fiber reinforcement polymers (GFRPs and CFRPs) were investigated systematically. Experimental studies showed that the 219% increase in buckling load and 661% in bending load were obtained with reinforcements. The use of plastics and metal together as a reinforced structure yields better mechanical performance properties such as high resistance to buckling and bending loads, dimensional stability and high energy absorption capacity, including weight reduction. While the thin-walled metallic component provides required strength and stiffness, the plastic component provides the support necessary to prevent premature buckling without adding significant weight to the structure. It is thought that the combination of these materials will offer a promising new focus of attention for designers seeking more appropriate composite beams with high buckling loads beside light weight. The developed plastic-metal hybrid-composite structure is promising especially for critical parts serving as a support member of vehicles for which light weight is a critical design consideration. (C) 2013 Elsevier Ltd. All rights reserved

Experimental and numerical study on the thermoforming process of amorphous thermoplastic polymers

Thickness distribution has an important impact on the quality of thermoformed products. It has significant effects not only on durability but also on the oxygen and gas transmission rate of thermoformed packaging products. In this study, acrylonitrile butadiene styrene and polystyrene sheets were thermoformed using a lab scale thermoforming machine. Three different mold shapes were considered: conical, spherical and cylindrical. The thickness distribution of thermoformed acrylonitrile butadiene styrene and polystyrene samples for each mold was investigated based on geometric element analysis (GEA) and finite element analysis (FEA). Finite element analysis yielded more accurate results than geometric element analysis. Process parameters such as temperature distribution on the sheets before mol ding, have a crucial effect on thickness distribution for all configurations.Scientific Research Projects Unit at Kirklareli University, Turkey [KLUBAP/055, KLUBAP/068]The authors thank Associate Prof. B. Onur Kucukyildirim for his contribution. This paper is based on the results of scientific research projects No. KLUBAP/055 and KLUBAP/068. These research projects were supported by the Scientific Research Projects Unit at Kirklareli University, Turkey.WOS:00046698510000

Simulation of nonlinear bending behavior and geometric sensitivities for tubular beams with fixed supports

In this study, the bending characteristics of thin-walled (D/t=30) tubular beams with fixed supports are systematically investigated for different beam lengths and diameters. Bending behavior of the beam is simulated using the finite element method, in which elasto-plastic material, large-deformation and contact are included. Stress distribution is monitored by FE analyses during bending simulation. Also, load carrying and energy absorption capacities of the tubular beams having different geometrical combinations are compared with each other. The results of finite element (FE) analyses indicate that the deformation characteristics and load carrying capacities of the beam strongly depend on the diameter. From the load-displacement curve, three distinct regions were observed and the associated deformation characteristics were identified. There is a noticeable correlation between the energy absorption and transition displacements for the ranges of geometric parameters coved in this study. It is concluded that the presented simulation results can provide significant contribution to the design of side-door impact beams and passive safety research. (C) 2011 Elsevier Ltd. All rights reserved

Effects of Pre-Forming Process and PVC Foam Reinforcement on the Deformation Behavior of Aluminum Tube under Axial Loading

In this study, the effects of pre-forming and foam reinforcement on the axial compression behavior of circular thin-walled aluminum tubes were experimentally investigated. Compression tests were performed in a computer controlled test machine at the cross-head speed of 1 mm/s. Pre-forming has changed the folding behavior of tube and increased the energy absorbing capacity 1.26 times that of empty tube. The PVC reinforcement has increased the energy absorbing capacity 1.22 times. PVC reinforcement increases the stability of tube wall deformation; hence it positively affects the energy absorption. The energy absorbing capacity of pre-formed and PVC foam reinforced tubes increase approximately 1.4 times that of empty tube. It was however shown that the reinforcement and pre-forming had no significant effect on the maximum load