Plastic collapse analysis of thin-walled circular tubes subjected to bending. Thin Walled Struct 47: 637-645

Thin-Walled Structures (Impact Factor: 1.75). 02/2009; 47(6). DOI: 10.1016/j.tws.2008.11.005


a b s t r a c t Circular tubes have been widely used as structural members in many engineering applications. Therefore, its collapse behavior has been studied for many decades, focusing on its energy absorption characteristics and collapse mechanism. In order to predict the collapse behavior of members, one could rely on the use of finite element codes or experiments. These tools are helpful and have high accuracy but are costly and require extensive running time. Therefore, an approximate model of tubes collapse mechanism is an alternative especially for the early step of design. This paper is also aimed to develop a closed-form solution to predict the moment–rotation response of circular tube subjected to pure bending. The model was derived based on the principle of energy rate conservation. The collapse mechanism was divided into three phases. New analytical model of ovalisation plateau in phase 2 was derived to determine the ultimate moment. In phase 3, the Elchalakani et al. model [Int. J. Mech. Sci. 2002; 44:1117–1143] was developed to include the rate of energy dissipation on rolling hinge in the circumferential direction. The 3-D geometrical collapse mechanism was analyzed by adding the oblique hinge lines along the longitudinal tube within the length of the plastically deformed zone. Then, the rates of internal energy dissipation were calculated for each of the hinge lines which were defined in terms of velocity field. Inextensional deformation and perfect plastic material behavior were assumed in the derivation of deformation energy rate. In order to compare, the experiment was conducted with a number of tubes having various D/t ratios. Good agreement was found between the theoretical prediction and experimental results.

Download full-text


Available from: Somya Poonaya, May 01, 2014
1 Follower
168 Reads
  • Source
    • "In this regard, a rib-reinforced thin-walled hollow tube-like beam was presented for potential application in vehicle bumper [9]. Poonaya et al. [10] provided a theoretical model to predict the collapse mechanism of thin-walled circular tube subjected to pure bending. Ayhan et al. [11] investigated the bending behavior of the beam by the finite element method and dealt with the correlation between the energy absorption and transition displacements for geometric parameters. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Crash components in automobiles are probably subjected to multiple loading conditions in real life, such as axial crushing and lateral bending. Unlike most of the existing work that solely focuses on the pure axial crushing or lateral bending, this paper attempts to accommodate both by proposing a novel structure, namely foam-filled thin-wall tube with functionally lateral graded thickness (FLGT). From numerical study of FLGT structures, they are found to exhibit noticeable advantage over the corresponding traditional uniform thickness (UT) structures with the same weight under both axial crushing and lateral bending. Moreover, the gradient governing the varying thickness shows significant influence on the crashworthiness performance of FLGT. To seek for the optimal gradient, a multi-objective optimization is carried out using multi-objective particle swarm optimization (MOPSO) algorithm, where response surface models are established to formulate the objectives functions, i.e. specific energy absorption (SEA) and peak impact force (Fpeak). The optimization results show that the foam-filled structure with FLGT can produce more promising Pareto solutions than traditional UT counterparts. Therefore, the FLGT structure could have potential applications subjected to different loading conditions.
    Thin-Walled Structures 06/2015; 91:63-71. DOI:10.1016/j.tws.2015.01.011 · 1.75 Impact Factor
  • Source
    • "The total energy absorption for the YLM model is Fig. 1. (a) Front view of deformed section (Poonaya et al. [20]), (b) ovalisation of hollow steel tube. Local deformation of bollard due to impact load Global deformation of bollard due to impact load Experimental observation to define a basic YLM model Fig. 2. Failure mode of steel hollow section. "
    [Show abstract] [Hide abstract]
    ABSTRACT: In order to prevent vehicle access to a protected area, vehicle barriers can be installed around the perimeter of the area. Bollards are commonly used as vehicle barriers. This is due to the fact that they can be readily blended with other architectural features and present fewer disturbances to a building’s functionality when compared to other barrier systems. Hollow steel tubes are used in a variety of barrier system applications where they are required to absorb deformation energy. Varying methods, such as finite element analysis or experimental observation, can be used to determine the collapse behaviour and energy absorption of these steel structures under lateral impact load. These methods have high accuracy but demand a significant amount of time and computational resources. Apart from experimental and numerical analyses, Yield Line Mechanism (YLM) is an approach that can provide the collapse response of sections. This is when a section fails and the YLM of failure forms at its localised plastic hinge point. The YLM analysis approach is commonly used to investigate the performance of thin-wall structures that have local failure mechanisms. This paper investigates the collapse behaviour and energy absorption capability of hollow steel tubes under large deformation due to lateral impact load. The YLM technique is applied using the energy method, and is based upon measured spatial plastic collapse mechanisms from experiments. Analytical solutions for the collapse curve and in-plane rotation capacity are developed, and are used to model the large deformation behaviour and energy absorption. The analytical results are shown to compare well with the experimental values. The YLM model is then used to verify the finite element model (FEM), and then the failure behaviour and energy absorption of hollow steel tubes under lateral impact load is investigated in more detail.
    Thin-Walled Structures 03/2015; 88. DOI:10.1016/j.tws.2014.11.024 · 1.75 Impact Factor
  • Source
    • "The proposed method showed to be a systematic and unified way to obtain the critical loads, the buckling modes and the initial slope of the bifurcated branch for rectangular plates under uniaxial or biaxial compression (-tension) and cylinders under axial compression, with various boundary conditions. In 2009, S. Poonaya, U. Teeboonma and C. Thinvongpituk analyzed the plastic collapse of thin-walled circular tubes subjected to bending [14] . 3-D geometrical collapse mechanism was analyzed by adding the oblique hinge lines along the longitudinal tube within the length of the plastically deformed zone. "
    [Show abstract] [Hide abstract]
    ABSTRACT: An expression for apparent strain of a pipe at plastic bending buckling status is proposed in the present paper. The material of the pipe is considered as a rigid-perfectly plastic one, and the cross section of the pipe during the pipe-bending process assumes to be elliptic gradually. The energy rate for the pure bending of the elliptic pipe is proposed firstly, and the energy rate of cross-sectional ovalizing of the pipe is derived afterward. Furthermore, both the energy rates are combined to analyze the pipe bending buckling. As a result, an apparent strain expression of a pipe at the plastic bending buckling status is proposed. The predicted result of the new strain expression of pipe bending at buckling status is compared with the available test data and shows that the new formula is reasonable.
    Journal of the Brazilian Society of Mechanical Sciences and Engineering 01/2015; DOI:10.1007/s40430-014-0302-4 · 0.43 Impact Factor
Show more