Dispersion Behaviors of Wedge Waves Propagating Along Wedges with Bilinear Cross Sections

2006 ◽  
Vol 321-323 ◽  
pp. 765-769
Author(s):  
Che Hua Yang ◽  
Chun Zen Tsen
Keyword(s):  
Finite Element ◽  
Cross Section ◽  
Cross Sections ◽  
Displacement Field ◽  
Acoustic Waves ◽  
Mode Coupling ◽  
Lamb Waves ◽  
Apex Angle ◽  
Ultrasonic Technique ◽  
Wedge Waves

Wedge waves (WW) are guided acoustic waves propagating along the tip of a wedge, with energy tightly confined near the apex. Like Lamb waves, wedge waves with displacement field anti-symmetric about the mid-apex-plane are called anti-symmetric flexural (ASF) modes. This study is focused on exploring the dispersion behaviors of ASF modes propagating along a bilinear wedge (BW). A BW is wedge with a cross section of two apex angles, compared with a linear wedge (LW) having a single apex angle. In the literature, many studies regarding to the dispersion behaviors of ASF modes are reported for LW, but not for BW. In this study, a laser ultrasonic technique and finite element simulations are used to investigate the dispersion behavior of BW-ASF modes. It is found out that a BW-ASF mode is a result of mode coupling between the two LW-ASF modes of the same order corresponding to the two apex angles of the BW.

Stress concentration factors for the torsion of curved beams of arbitrary cross-section

2006 ◽  
Vol 220 (12) ◽  
pp. 1709-1726 ◽  
Author(s):  
R E Cornwell
Keyword(s):  
Finite Element ◽  
Stress Concentration ◽  
Cross Section ◽  
Cross Sections ◽  
Shear Stresses ◽  
Curved Beams ◽  
Finite Element Implementation ◽  
Out Of Plane ◽  
Concentration Factors ◽  
Stress Concentration Factors

There are numerous situations in machine component design in which curved beams with cross-sections of arbitrary geometry are loaded in the plane of curvature, i.e. in flexure. However, there is little guidance in the technical literature concerning how the shear stresses resulting from out-of-plane loading of these same components are effected by the component's curvature. The current literature on out-of-plane loading of curved members relates almost exclusively to the circular and rectangular cross-sections used in springs. This article extends the range of applicability of stress concentration factors for curved beams with circular and rectangular cross-sections and greatly expands the types of cross-sections for which stress concentration factors are available. Wahl's stress concentration factor for circular cross-sections, usually assumed only valid for spring indices above 3.0, is shown to be applicable for spring indices as low as 1.2. The theory applicable to the torsion of curved beams and its finite-element implementation are outlined. Results developed using the finite-element implementation agree with previously available data for circular and rectangular cross-sections while providing stress concentration factors for a wider variety of cross-section geometries and spring indices.

scholarly journals Membrane analogy for multi-material bars under torsion

2019 ◽  
Vol 475 (2225) ◽  
pp. 20190124 ◽  
Author(s):  
Laura Galuppi ◽  
Gianni Royer-Carfagni
Keyword(s):  
Finite Element ◽  
Cross Section ◽  
Cross Sections ◽  
Three Dimensional ◽  
Element Model ◽  
Elastic Problem ◽  
Two Dimensional ◽  
Torsion Problem ◽  
Linear Elastic ◽  
Physical Apparatus

Prandtl's membrane analogy for the torsion problem of prismatic homogeneous bars is extended to multi-material cross sections. The linear elastic problem is governed by the same equations describing the deformation of an inflated membrane, differently tensioned in regions that correspond to the domains hosting different materials in the bar cross section, in a way proportional to the inverse of the material shear modulus. Multi-connected cross sections correspond to materials with vanishing stiffness inside the holes, implying infinite tension in the corresponding portions of the membrane. To define the interface constrains that allow to apply such a state of prestress to the membrane, a physical apparatus is proposed, which can be numerically modelled with a two-dimensional mesh implementable in commercial finite-element model codes. This approach presents noteworthy advantages with respect to the three-dimensional modelling of the twisted bar.

Support-Condition Analyses of Rotating Beams Under Distributed Imbalance Loading

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.

Residual stress distribution in built-in beams

2020 ◽  
pp. 146442072095861
Author(s):  
FA de Castro ◽  
Paulo P Kenedi ◽  
LL Vignoli ◽  
I I T Riagusoff
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Stress Distribution ◽  
Cross Section ◽  
Cross Sections ◽  
Element Model ◽  
Residual Stress Distribution ◽  
Concentrated Load ◽  
Load Growth ◽  
Final Failure

Metallic hyperstatic structures, like beams, submitted to excessive loads, do not fail completely before fully yielding in more than one cross section. Indeed, for built-in beams, three cross sections must be fully yielded before the final failure can occur. So, modeling the evolution of the cross-section residual stress distribution is an important subject that should be addressed to guarantee the stress analysis modeling correctness. This paper analyses the residual stress distribution evolution, in critical cross sections, of built-in beams during a transversal concentrated load growth, until the final failure through hinges formation. A finite element model is also presented. The results show good matches with the numerical model, used as a reference.

Numerical Modelling of Metal Foams with Weaire-Phelan Cell

2013 ◽  
Vol 334-335 ◽  
pp. 122-126 ◽  
Author(s):  
Sid Ali Kaoua ◽  
Haddad Meriem ◽  
Dahmoun Djaffar ◽  
Azzaz Mohammed
Keyword(s):  
Finite Element ◽  
Cross Section ◽  
Cross Sections ◽  
Metal Foam ◽  
Metallic Foam ◽  
Geometrical Parameters ◽  
The Finite Element Method ◽  
Geometrical Characteristics ◽  
Structural Network ◽  
Regular Network

The mechanical properties of open-cell metal foam structures are investigated using the finite element method. The foam structure is modelled by a regular network of anisotropic Weaire-Phelan cells in which the strands are modelled as 3D finite element beams. We consider four types of strand cross sections: (i) circular, (ii) square, (iii) triangular and (iv) Plateau border shape. The numerical results obtained with our proposed mathematical model are checked against the experimental results obtained on real Nickel metallic foam and an excellent agreement is found. In addition, we conducted a parametric analysis to study the effect of some geometrical characteristics on the elasticity of the metal foam. Among these geometrical parameters, the shape, the dimensions of strand cross section, the inertia, the alignment of strands and the structural network irregularities are investigated, discussed and documented.

Finite Element Analysis on the Blast Resistant Performance of Multibarrel Tube-Confined Concrete Column in Different Cross-Sections

2013 ◽  
Vol 721 ◽  
pp. 545-550
Author(s):  
Sai Wu ◽  
Jun Hai Zhao ◽  
Er Gang Xiong
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Detonation Wave ◽  
Cross Section ◽  
Cross Sections ◽  
Failure Modes ◽  
Circular Cross Section ◽  
Blast Load ◽  
Element Analysis ◽  
The Impact

Based on the finite element analysis software ANSYS/LS-DYNA, this paper numerically analyzed the dynamic performance of MTCCCs with different cross sections under blast load, followed by the study and comparison on the differences of the detonation wave propagation and failure modes between the columns in circular cross section and square cross section. The results show: The blast resistant performance of the circular component is more superior than the square component for its better aerodynamic shape that can greatly reduce the impact of the detonation wave on the column; The main difference of the failure modes between the circular and square cross-sectional components under blast load lies in the different failure mode of the outer steel tube. The simulation results in this paper can provide some references for the blast resisting design of MTCCCs.

Simulations of the Effects of Mold Properties on Directional Solidification

2013 ◽  
Author(s):  
Mark A. Lauer ◽  
David R. Poirier ◽  
Robert G. Erdmann ◽  
Luke Johnson ◽  
Surendra N. Tewari
Keyword(s):  
Finite Element ◽  
Thermal Properties ◽  
Mushy Zone ◽  
Phase Change ◽  
Directional Solidification ◽  
Cross Section ◽  
Cross Sections ◽  
Mold Wall ◽  
Solidification Process ◽  
Thermosolutal Convection

The mold geometry and its thermal properties greatly influence the solidification process. Finite element simulations of directional solidification in various molds are presented. These simulations were performed using volume averaged properties in the mushy zone in order to model the convection, transport of solute and energy, and phase change occurring during solidification. These simulations show the interactions of the mold and alloy with the resultant solidification phenomena, including steepling. Mold geometries can cause macrosegregation because of shrinkage flows, by interrupting the development of the mushy zone, and by causing or influencing thermosolutal convection. Mold materials with different thermal properties result in different macrosegregation patterns even for the same geometries. Changes in cross section and the thermal properties of the mold also affect the gradients and solidification rates obtained in the alloy, as opposed to those measured on the mold wall. Simulations are compared qualitatively to a verification experiment of directionally solidifying a hypoeutectic Al-7wt%Si alloy in a mold with changing cross sections.

scholarly journals Challenges Faced While Designing Body in White

2021 ◽  
Vol 9 (9) ◽  
pp. 49-56
Author(s):  
Aditya Dhobale
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Cross Section ◽  
Cross Sections ◽  
Element Analysis ◽  
Computer Aided ◽  
Safety Parameters ◽  
Body In White ◽  
White Sheet ◽  
Metal Design

Abstract: Construction of Body in White (BiW) revolves around plenty of challenges. Ranging from BiW fixtures to curbing weight of Body in White sheet metal design. This paper discusses about all the design aspects in BiW manufacturing in automobile and confronting challenges that occurs. At present, lots of existing theories are being applied and efforts to improve the same are being made. This paper provides a path on how components can be developed and make necessary improvements. CAE (Computer Aided Engineering) tools have been used for FEA (Finite Element Analysis) and also an example of stress analysis of automotive chassis is given. An outcome depending on behaviour of loads acting on frame is drawn. The importance of hollow tubes, tubes of different- cross sections to counter weight and ease the designing of BiW frame have been proposed. This paper also provides insight on safety parameters with current construction of tubular frame chassis. Other solutions such as hybrid tubes, foam padding and plastic trim have been pointed out in this paper. Keywords: CAE, FEA, manufacturing, loads, tubes, cycle-time, cross-section.

scholarly journals Analysis of cold formed steel sheet pile for earth retaining wall

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
C. Veena ◽  
S Saravanan ◽  
Robin Davis P. ◽  
Nandakumar Gopalan
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Cross Section ◽  
Cross Sections ◽  
Failure Load ◽  
Unit Cell ◽  
Bending Stress ◽  
Sheet Pile ◽  
Element Analysis ◽  
Cold Formed Steel

Failure loads of sheet pile having various profiles such as U, Z and Omega/Hat profiles under compression was carried out by using equations of strength of materials and compared the failure load under various modes such as Euler’s buckling, torsional buckling and failure load due to yielding. Compared the strength of various profiles under flexure by using finite element analysis. Sheet pile can be analyzed as a unit cell for the simplified finite element analysis. For selecting the unit cell sheet pile with omega/Hat section was analyzed for profile containing one to eight numbers and checked the convergence of bending stress and maximum lateral deflection. Interlocks were analyzed for three different conditions such as plane interlock, interlock filled with bitumen and welded interlock. Location of interlock and neutral axis of the wall will affect the stability of the structure. Sheet piles with various cross sections were analyzed and studied the shear stress and bending stress along the cross section. From the structural performance of various cross sections omega/hat section can be considered as the most efficient cross section for the cold formed steel sheet pile because of its more load carrying capacity under compression and high torsion resistance and less bending stress. Results from the finite element analysis for the selection of unit cell shows that the stress and deflection value was converge at the sheet pile having 6 numbers of profiles. Keywords: sheet piles, building, resistance.

Saint-Venant Decay Rates for the Rectangular Cross Section Rod

2004 ◽  
Vol 71 (3) ◽  
pp. 429-433 ◽  
Author(s):  
N. G. Stephen ◽  
P. J. Wang
Keyword(s):  
Finite Element ◽  
Aspect Ratio ◽  
Transfer Matrix ◽  
Cross Section ◽  
Cross Sections ◽  
Rectangular Cross Section ◽  
Decay Rates ◽  
Elastic Rod ◽  
Cross Sectional ◽  
Element Transfer

A finite element-transfer matrix procedure developed for determination of Saint-Venant decay rates of self-equilibrated loading at one end of a semi-infinite prismatic elastic rod of general cross section, which are the eigenvalues of a single repeating cell transfer matrix, is applied to the case of a rectangular cross section. First, a characteristic length of the rod is modelled within a finite element code; a superelement stiffness matrix relating force and displacement components at the master nodes at the ends of the length is then constructed, and its manipulation provides the transfer matrix, from which the eigenvalues and eigenvectors are determined. Over the range from plane stress to plane strain, which are the extremes of aspect ratio, there are always eigenmodes which decay slower than the generalized Papkovitch-Fadle modes, the latter being largely insensitive to aspect ratio. For compact cross sections, close to square, the slowest decay is for a mode having a distribution of axial displacement reminiscent of that associated with warping during torsion; for less compact cross sections, slowest decay is for a mode characterized by cross-sectional bending, caused by self-equilibrated twisting moment.

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