A cross-section deformable beam finite element model for fire simulations of thin-walled steel columns

Tapered thin-walled structures have been widely used in wind turbine and rotor blade. In this paper, a spectral finite element model is developed to investigate tapered thin-walled beam structures, in which torsion related warping effect is included. First, a set of fully coupled governing equations are derived using Hamilton’s principle to account for axial, bending, and torsion motion. Then, the differential transform method (DTM) is applied to obtain the semianalytical solutions in order to formulate the spectral finite element. Finally, numerical simulations are conducted for tapered thin-walled wind turbine rotor blades and validated by the ANSYS. Modal frequency results agree well with the ANSYS predictions, in which approximate 30,000 shell elements were used. In the SFEM, one single spectral finite element is needed to perform such calculations because the interpolation functions are deduced from the exact semianalytical solutions. Coupled axial-bending-torsion mode shapes are obtained as well. In summary, the proposed spectral finite element model is able to accurately and efficiently to perform the modal analysis for tapered thin-walled rotor blades. These modal frequency and mode shape results are important to carry out design and performance evaluation of the tapered thin-walled structures.

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Support-Condition Analyses of Rotating Beams Under Distributed Imbalance Loading

Volume 7: Dynamic Systems and Control; Mechatronics and Intelligent Machines, Parts A and B ◽

10.1115/imece2011-62651 ◽

2011 ◽

Author(s):

Kai Jokinen ◽

Erno Keskinen ◽

Marko Jorkama ◽

Wolfgang Seemann

Keyword(s):

Finite Element ◽

Finite Element Model ◽

Cross Section ◽

Cross Sections ◽

Natural Frequencies ◽

Element Model ◽

Mode Shapes ◽

Constant Cross Section ◽

Support Condition ◽

Beam Elements

In roll balancing the behaviour of the roll can be studied either experimentally with trial weights or, if the roll dimensions are known, analytically by forming a model of the roll to solve response to imbalance. Essential focus in roll balancing is to find the correct amount and placing for the balancing mass or masses. If this selection is done analytically the roll model used in calculations has significant effect to the balancing result. In this paper three different analytic methods are compared. In first method the mode shapes of the roll are defined piece wisely. The roll is divided in to five parts having different cross sections, two shafts, two roll ends and a shell tube of the roll. Two boundary conditions are found for both supports of the roll and four combining equations are written to the interfaces of different roll parts. Totally 20 equations are established to solve the natural frequencies and to form the mode shapes of the non-uniform roll. In second model the flexibility of shafts and the stiffness of the roll ends are added to the support stiffness as serial springs and the roll is modelled as a one flexibly supported beam having constant cross section. Finally the responses to imbalance of previous models are compared to finite element model using beam elements. Benefits and limitations of each three model are then discussed.

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Numerical study of heat transfer characteristics in positional wire and arc additive manufacturing

Rapid Prototyping Journal ◽

10.1108/rpj-01-2020-0016 ◽

2020 ◽

Vol 26 (9) ◽

pp. 1627-1635

Author(s):

Dongqing Yang ◽

Jun Xiong ◽

Rong Li

Keyword(s):

Heat Transfer ◽

Finite Element ◽

Additive Manufacturing ◽

Temperature Distribution ◽

Finite Element Model ◽

Heat Dissipation ◽

Element Model ◽

Heat Transfer Characteristics ◽

Content Type ◽

Thin Walled

Purpose This paper aims to fabricate inclined thin-walled components using positional wire and arc additive manufacturing (WAAM) and investigate the heat transfer characteristics of inclined thin-walled parts via finite element analysis method. Design/methodology/approach An inclined thin-walled part is fabricated in gas metal arc (GMA)-based additive manufacturing using a positional deposition approach in which the torch is set to be inclined with respect to the substrate surface. A three-dimensional finite element model is established to simulate the thermal process of the inclined component based on a general Goldak double ellipsoidal heat source and a combined heat dissipation model. Verification tests are performed based on thermal cycles of locations on the substrate and the molten pool size. Findings The simulated results are in agreement with experimental tests. It is shown that the dwell time between two adjacent layers greatly influences the number of the re-melting layers. The temperature distribution on both sides of the substrate is asymmetric, and the temperature peaks and temperature gradients of points in the same distance from the first deposition layer are different. Along the deposition path, the temperature distribution of the previous layer has a significant influence on the heat dissipation condition of the next layer. Originality/value The established finite element model is helpful to simulate and understand the heat transfer process of geometrical thin-walled components in WAAM.

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Joint Stiffness of 3D Space Frame Thin Walled Structural Joint Considering Local Buckling Effect

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.660.773 ◽

2014 ◽

Vol 660 ◽

pp. 773-777

Author(s):

Mohd Shukri Yob ◽

Shuhaimi Mansor ◽

Razali Sulaiman

Keyword(s):

Finite Element ◽

Finite Element Model ◽

Joint Stiffness ◽

Element Model ◽

Joint Effect ◽

Experimental Result ◽

Space Frame ◽

3D Space ◽

Structural Joint ◽

Thin Walled

Thin walled structure is widely used in designing light weight vehicle. For automotive industry, weight is an important characteristic to increase performance of a vehicle. Vehicle structures are built from thin walled beams by joining them using various joining methods and techniques. For a structure, its stiffness greatly depends on joint stiffness. However, stiffness of thin walled beam is difficult to predict accurately due to buckling effect. Once the beams are joined to form a structure, it will expose to joint flexibility effect. A lot of researches had been done to predict the behaviors of thin walled joint analytically and numerically. However, these methods failed to come out with satisfactory result. In this research work, finite element model for 3D space frame thin walled structural joint is developed using circular beam element by validating with experimental result. Another finite element model using rigid element is used to represent 3D space frame behavior without joint effect. The difference between these 2 models is due to joint effect. By using same modelling technique, joint stiffness for different sizes can be established. Then, the relation between joint stiffness for 3D space frame and size of beam can be obtained.

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