• 한국자동차공학회논문집
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• 제16권4호
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• pp.81-87
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• 2008

In this study, concerns the crashworthiness of the widely used vehicle structure, square thin-walled tubes, which are excellent on the point of the energy absorbing capacity. An experimental investigation was carried out to study the energy absorption characteristics of thin-walled square tubes subjected to dynamic crushing by axial loading to develop the optimum structural members. The impact velocity was tested in the rage $4.698{\sim}8.2m/s$. To efficiently review the collapse characteristics of these sections, the simulation have been carried out using explicit FEM package, LS-DYNA. The solutions compared with results the impact collapse experiment. Here, the controller are introduced to improve and control the absorbed energy of thin-walled square tubes in this paper. To predict and control the energy absorption, we designed it in consideration to the it's influence, height, thickness, wide ratio in this study. When the controller used, the experimental results of crushing of square tubes controlled by the controller's elements showed a good candidate for a controllable energy absorption capability in impact axial crushing.

• 전산구조공학
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• 제9권4호
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• pp.135-140
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• 1996

박벽개단면을 갖는 단일 형강재는 압축재로 될 수 있는데 예를 들면 트러스에서 복재가 이런 경우이다. 이 때에는 부재의 조립 때문에 발생하는 필연적 편심을 구조설계시에는 보통 무시한다. 그러나 편심의 영향은 부재를 설계할 때, 특히 압축부재의 설계에서는 고려되어야 할 사항이다. 비틀림이나 혹은 휨과 비틀림에 의해서 좌굴을 일으키는 압축재의 임계하중은 지배하는 비분방정식의 해를 구함으로써 결정된다. 본 논문에서는 채널([), 등변앵글(L), 리프채널(C)의 편심변화에 따른 내하력을 도표로 나타내기로 한다. 또한 식이복잡하므로 컴퓨터를 이용하여 계산한 후, 그 결과를 SURFER프로그램을 사용하여 그래프로 표시하였다.

• Interaction and multiscale mechanics
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• 제1권1호
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• pp.143-156
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• 2008

Elliptical tubes may buckle in an elastic local buckling failure mode under uniform compression. Previous analyses of the local buckling of these members have assumed that the cross-section is hollow, but it is well-known that the local buckling capacity of thin-walled closed sections may be increased by filling them with a rigid medium such as concrete. In many applications, the medium many not necessarily be rigid, and the infill can be considered to be an elastic material which interacts with the buckling of the elliptical tube that surrounds it. This paper uses an energy-based technique to model the buckling of a thin-walled elliptical tube containing an elastic infill, which elucidates the physics of the buckling phenomenon from an engineering mechanics basis, in deference to a less generic finite element approach to the buckling problem. It makes use of the observation that the local buckling in an elliptical tube is localised with respect to the contour of the ellipse in its cross-section, with the localisation being at the region of lowest curvature. The formulation in the paper is algebraic and it leads to solutions that can be determined by implementing simple numerical solution techniques. A further extension of this formulation to a stiffness approach with multiple degrees of buckling freedom is described, and it is shown that using the simple one degree of freedom representation is sufficiently accurate for determining the elastic local buckling coefficient.

• Steel and Composite Structures
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• 제4권4호
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• pp.281-301
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• 2004

The paper begins by presenting a unified variational approach to the lateral-torsional buckling (LTB) analysis of doubly symmetric prismatic and tapered thin-walled beams with open cross-sections, which accounts for the influence of the pre-buckling deflections. This approach (i) extends the kinematical assumptions usually adopted for prismatic beams, (ii) consistently uses shell membrane theory in general coordinates and (iii) adopts Trefftz's criterion to perform the bifurcation analysis. The proposed formulation is then applied to investigate the influence of the pre-buckling deflections on the LTB behaviour of prismatic and web-tapered I-section simply supported beams and cantilevers. After establishing an interesting analytical result, valid for prismatic members with shear centre loading, several elastic critical moments/loads are presented, discussed and, when possible, also compared with values reported in the literature. These numerical results, which are obtained by means of the Rayleigh-Ritz method, (i) highlight the qualitative differences existing between the LTB behaviours of simply supported beams and cantilevers and (ii) illustrate how the influence of the pre-buckling deflections on LTB is affected by a number of factors, namely ($ii_1$) the minor-to-major inertia ratio, ($ii_2$) the beam length, ($ii_3$) the location of the load point of application and ($ii_4$) the bending moment diagram shape.

• Steel and Composite Structures
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• 제35권5호
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• pp.701-715
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• 2020

Steel storage racks are lightweight structures, made of thin-walled cold-formed members, whose behaviour is remarkably influenced by local, distortional and overall buckling phenomena, frequently mutually combined. In addition, the need of an easy and rapid erection and reconfiguration of the skeleton frame usually entails the presence of regular perforations along the length of the vertical elements (uprights). Holes and slots strongly influence their behaviour, whose prediction is however of paramount importance to guarantee an efficient design and a safe use of racks. This paper focuses on the behaviour of isolated uprights subjected to both axial load and bending moments, differing for the cross-section geometry and for the regular perforation systems. According to the European standards for routine design, four alternatives to evaluate the bending moment-axial load resisting domains are shortly discussed and critically compared in terms of member load carrying capacity.

• 한국자동차공학회논문집
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• 제3권5호
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• pp.74-81
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• 1995

In this paper, the crushing tests of circular tubes under axial impact loading are conducted to investigate the energy absorption abilities. A cross head with 18kg launched by the compressed air collides against circular tubes. Circular tubes used for this experiment are Al and CFRP laminates, which have 8 ply with $15^{\circ}$ and $45^{\circ}$. The absorbed energy unit mass and volume of the CFRP specimen with $15^{\circ}$ are higher than those of aluminum specimen. CFRP specimen having small stacking angle have better energy absorption abilities than that of large stacking angle.

• 국제초고층학회논문집
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• 제8권3호
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• pp.161-167
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• 2019

Making full use of material strength, maintaining sufficient ductility of structural components, and ensuring simple and robust connections are crucial to the development of steel-concrete composite structures. The steel-tubed concrete structure uses thin-walled steel tube to provide confinement, so that the strength and ductility of the concrete core are improved. Meanwhile, the thin-walled steel tube is terminated at the beam-column joint to avoid the local buckling problem and simplify the connections between steel tube and RC members. A brief overview of the development of steel-tubed concrete structures is presented. Through the discussion on the structural behavior of steel-tubed concrete and the introduction of typical practical projects, the prospects for future research are highlighted.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.480-485
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• 2004

The applications of composite materials have increased over the past few decades in a variety of structures that require high ratio of stiffness and strength to weight ratios. Recently the thick open section composite beams are used extensively as load carrying members and stiffeners of structural elements. However, most of studies on thick composite beams are limited only to closed section beams. In this study, an open cross-section thick-walled composite beam model which includes coupled stiffness, transverse shear, and warping effects is suggested and the deflections associated with the thick-walled composite beams and thin-walled composite beams are obtained and compared with the finite element analysis results.

• Steel and Composite Structures
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• 제5권6호
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• pp.515-533
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• 2005

Buckling and post-buckling of cold-formed steel members are rather difficult to predict due to material and geometrical non-linearity. However, numerical techniques have reached a level of maturity such that many are now successfully undertaking ultimate strength analysis of cold-formed steel members. In numerical non-linear analysis, both geometrical and material imperfections, have to be estimated and properly used. They must be codified in terms of shape and magnitude. The presented paper represents a state-of-art report, including relevant results obtained by the authors and collected from literature, on that problem.

• 한국정밀공학회지
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• 제20권10호
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• pp.177-182
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• 2003

The front-end side members of automobiles absorb most of the energy in a case of front-end collision. The front-end side members are required to have a high stiffness together with easiness to collapse sequentially to absorb more impact energy. The axial static collapse test (5mm/min) was conducted by using UTM for form different types of members which have different cross section shapes; single hat, single cap, double cap, and double hat. The single hat shaped section member has the typical standard section, which the double hat shape section has a symmetry in the center to have more stiffness. As a result of the test, the energy absorbing characteristic was analyzed for different section shapes. It turned out that the change of section shape influence the absorbing energy, the mean collapse load and the maximum collapse load, and the relation between the change of section shape and the collapse mode.