| 1. |
- Asnafi, Nader, 1960-
(författare)
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Analytical modelling of tube hydroforming
- 1999
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Ingår i: Thin-walled structures. - : Elsevier. - 0263-8231 .- 1879-3223. ; 34:4, s. 295-330
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Tidskriftsartikel (refereegranskat)abstract
- The automotive industry has shown a growing interest in tube hydroforming during the past years. The advantages of hydroforming (less thinning, a more efficient manufacturing process etc.) can, for instance, be combined with the high strength of extra high strength steels, which are usually less formable, to produce structural automotive components which exhibit lower weight and improved service performance. Design and production of tubular components require knowledge about tube material behaviour and tribological effects during hydroforming and how the hydroforming operation itself should be controlled. These issues are studied analytically in the present paper. Hydroforming consists of free forming and calibration. Only the so-called free forming is treated here. The analytical models constructed in this paper are used to show what the limits are during the free forming, how different material and process parameters influence the loading path and the forming result, and what an experimental investigation into hydroforming should focus on. The present study was a part of a larger investigation, in which finite-element simulations and experiments were also conducted. The results of these simulations and experiments will be accounted for in coming papers.
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| 2. |
- Asnafi, Nader, 1960-, et al.
(författare)
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New lightweight metal-composite-metal panel for applications in the automotive and other industries
- 2000
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Ingår i: Thin-walled structures. - : Elsevier. - 0263-8231 .- 1879-3223. ; 36:4, s. 289-310
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Tidskriftsartikel (refereegranskat)abstract
- A new lightweight metal-composite-metal (MCM) panel is developed. This panel consists of two layers of 0.2-mm thick stainless steel sheet with a layer of woven fabric (semi-flexible composite) in between. The stiffness and the dent resistance of this MCM-panel are compared to those of corresponding panels pressed in 1-mm thick aluminum, 0.8-mm thick carbon steel and 0.8-mm thick stainless steel sheets. Compared to the aluminum panel, the MCM-panel exhibits a slightly smaller stiffness. However, the MCM-panel displays a larger dent resistance than the aluminum and the carbon steel panels. The new panel is 46% heavier than the aluminum panel. However, it is 60% lighter than the carbon and stainless steel panels. This new panel is expected to have many applications in manufacturing of parts for car, train and bus bodies, appliances and household machines. Machine chassis and air cargo containers are other examples of products, in which the new panel can be used. Production of the new panel requires that the tools be heated. The cycle time is short, since a newly developed and patented method for ultra-rapid heating of tools has been used in this study. The production is economical, since the cycle times is short and recycled fibres can be used. The production process is not completely optimized yet. However, the conducted experiments show that the panel stiffness and dent resistance are benefitted, if the tool pressure applied during the heating is low.
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| 3. |
- Höglund, Torsten, et al.
(författare)
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Slotted steel studs to reduce thermal bridges in insulated walls
- 1998
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Ingår i: Thin-walled structures. - 0263-8231 .- 1879-3223. ; 32:1-3, s. 81-109
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Tidskriftsartikel (refereegranskat)abstract
- The development of the slotted steel stud made it possible to use steel in external walls in countries with cold climate, like Sweden. By slotting the web the thermal bridges are significantly reduced. Several fabricators of lightweight constructions in Scandinavia now have slotted studs in their range, intended for load-bearing external walls in single family houses and for infill walls in blocks of flats. The development of the slotted stud has also led to the development of the building system for residential called Light Steel Framing.This paper mainly considers design methods for slotted steel studs for external walls. The importance of the slotted stud for the Light Steel Framing System is lighten up by a description of building components as exterior walls, interior walls and light weight floor structures. The thermal properties, sound insulation, springiness and vibrations, fire proof are described as well as building services, architecture, planning and production.
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| 4. |
- Stehn, Lars, et al.
(författare)
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Resistance and thermal insulation of a composite FRP-steel beam
- 2001
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Ingår i: Thin-walled structures. - 0263-8231 .- 1879-3223. ; 39:5, s. 375-394
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Tidskriftsartikel (refereegranskat)abstract
- For an optimal design of roof-elements for long spans one has to consider both load-carrying capacity and heat conductivity. In this paper three different alternative web configurations for joining web to flange in a roof-element are investigated. A composite web in combination with fibre reinforced plastics (FRP) is proposed as a solution to achieve an optimised performance. The connection is designed as a mechanical pin-type fastener with a general purpose polyester matrix FRP. Full-scale beam tests and small-scale properties test were carried out. Where connection failure took place, the derived connection capacity load matches fairly. A predicted span length of a roof element is in the order of 8-10 m in a design situation should be possible using the FRP-steel web. The load-carrying and thermal insulation performance of FRP-steel, expanded metal and slotted steel beams are compared by finite element analysis
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| 5. |
- Alsafadie, R., et al.
(författare)
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Three-dimensional formulation of a mixed corotational thin-walled beam element incorporating shear and warping deformation
- 2011
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Ingår i: Thin-walled structures. - : Elsevier. - 0263-8231 .- 1879-3223. ; 49:4, s. 523-533
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a corotational formulation of a three-dimensional elasto-plastic mixed beam element that can undergo large displacements and rotations. The corotational approach applies to a two-noded element a coordinate system which continuously translates and rotates with the element. In this way, the rigid body motion is separated out from the deformational motion. In this paper, a mixed formulation is adopted for the derivation of the local element tangent stiffness matrix and nodal forces based on a two-field Hellinger-Reissner variational principle. The local beam kinematics is based on a low-order nonlinear strain expression using Timoshenko assumption. The warping effects are characterized by adopting Benscoter theory that describes the warping degree of freedom by an independent function. Shape functions that satisfy the nonlinear local equilibrium equations are selected for the interpolation of the stress resultants. This local element, together with the corotational framework, can be used to analyze the nonlinear buckling and postbuckling of thin-walled beams with generic cross-section. The mixed formulation solution is compared against the results obtained from a corotational displacement-based formulation having the same beam kinematics. The superiority of the mixed formulation is clearly demonstrated.
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| 6. |
- Andrade, Pedro, et al.
(författare)
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On global and local buckling response of structural angle sandwich panels
- 2022
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Ingår i: Thin-walled structures. - : Elsevier. - 0263-8231 .- 1879-3223. ; 180
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Tidskriftsartikel (refereegranskat)abstract
- Having in mind the topic of industrialised construction and the benefits of modular construction, sandwich panels are investigated to be utilised as load-bearing wall elements. To assess its full potential, the present paper tackles the linear elastic buckling response of axially loaded angle sandwich panels, by means of numerical and analytical calculations, as the upper bound of its load bearing capacity. The failures modes are obtained and framed for concentrically loaded angle panels with fixed and pin-ended supports. A parametric study of the angle panel comprising a series of finite element models is undertaken where responses are compared with analytical calculations based on the theory of sandwich panels. Boundaries for local and global buckling are identified and framed.
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| 7. |
- Carlberger, Thomas, et al.
(författare)
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Dynamic testing and simulation of hybrid joined bi-material beam
- 2010
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Ingår i: Thin-walled structures. - : Elsevier. - 0263-8231 .- 1879-3223. ; 48:8, s. 609-619
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Tidskriftsartikel (refereegranskat)abstract
- A specimen is developed for real-like low velocity impact testing of bi-material joint configurations. Six different joint configurations are analysed. Two engineering adhesives are evaluated with and without discrete mechanical fasteners, i.e. adhesive and hybrid joints. Experiments and simulations are performed. The simulations are performed using adhesive cohesive finite elements. Simulations show good agreement with experiments in impact energy and overall deformation mode. The histories of applied load vs. load-point deflection show reasonably good correlation. The results show that the impact energy consumption depends on the joint integrity. A threshold value for the fracture energy of the adhesive seems to exist. Beneath this value, adhesive and discrete fastener work together increasing the impact energy capacity. Above this value the discrete fastener has a negative effect, and may be regarded as a stress concentration.
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| 8. |
- Khan, Sabih Ahmad, et al.
(författare)
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Investigation of the mechanical behavior of FDM processed CFRP/Al hybrid joint at elevated temperatures
- 2023
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Ingår i: Thin-walled structures. - : Elsevier BV. - 0263-8231 .- 1879-3223. ; 192
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Tidskriftsartikel (refereegranskat)abstract
- This research is focused on investigating the mechanical behavior of Fused Deposition Modeling (FDM) processed CFRP/Al hybrid riveted joints at elevated temperatures. A two-pronged approach was adopted entailing experimental and computational domains. In the experimental thrust, the developed joint was evaluated for its mechanical behavior by employing Digital Image Correlation, micro-XCT, and fractographic analysis. The tensile testing was performed at four different temperatures, i.e., Room Temperature (RT), 50°C, 75°C, and 100 °C. At RT, the joint experienced net-sectioning in the CFRP sheet along with minute secondary bending. Further, distinct failure modes were noticed for each ply orientation where the inherent porosity/voids appeared as the governing factor for the damage progression. Novel constitutive models were developed using accrued strain and change in energy dissipation to estimate the damage progression. The damage accumulation was found to be more uniform in the 0° layer as compared to 90°. Moreover, the 90° layer exhibited a more catastrophic damage pattern toward final failure. At elevated temperatures, a significant reduction in mechanical properties along with a non-uniform warping/bending of the plies was noticed due to viscoelastic behavior change. The computational analysis, having a hierarchical approach, was performed for the validation of the experimental results, and both were found to be in good agreement.
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| 9. |
- Possidente, Luca, et al.
(författare)
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Branch-switching procedure for post-buckling analysis of thin-walled steel members at elevated temperature
- 2019
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Ingår i: Thin-walled structures. - : Elsevier. - 0263-8231 .- 1879-3223. ; 136, s. 90-98
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Tidskriftsartikel (refereegranskat)abstract
- The paper investigates the effects of the geometrical imperfections in buckling analyses of plated steel elements at elevated temperatures and provides an alternative branch-switching procedure to perform post-buckling analyses without introducing initial imperfections into the model. This procedure is appealing since the choice of appropriate imperfections in classical analyses is not straightforward, above all at elevated temperature. Several numerical analyses show that the choice of the imperfections is not trivial and that the buckling mode may vary with temperature. They also show that the proposed branch-switching procedure is an interesting preliminary tool to understand the instability behaviour of steel structural members.
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| 10. |
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