Wave Analysis for In-Plane Vibration of Angular and Curved Frames

2021 ◽  
Vol 143 (6) ◽  
Author(s):  
B. K. Syam ◽  
Abhijit Sarkar
Keyword(s):  
High Frequency ◽  
Computational Simulation ◽  
Fem Simulation ◽  
Present Formulation ◽  
Excellent Correlation ◽  
Equilibrium Conditions ◽  
Reflection And Transmission ◽  
Structural Applications ◽  
Commercial Package ◽  
Computationally Intensive

Abstract In many structural applications like bridges, arches, etc., frames are used, and it is important to study their dynamic behavior. Finite element method (FEM) is usually used for computational simulation of vibration for such frame structures. However, FEM simulations for high frequency are computationally intensive and lack accuracy. This paper proposes a wave propagation-based approach for the vibration analysis of a frame having angular and curved joints. The reflection and transmission matrices for the joints are derived using the kinematic compatibility and equilibrium conditions. Reflection, transmission, and propagation matrices are assembled leading to matrix equation terms of the wave amplitudes. Modal analysis and harmonic analysis of frames having curved and angular joints are performed using the present formulation. The frequency response function for point harmonic forcing acting on such structures is also presented. The formulation and the results are non-dimensionalized for wider applicability. The results obtained using the present formulation are compared with those obtained through FEM simulation in a commercial package. It is found that the results obtained using the two methods are in excellent correlation. The computational efficiency of the present method over FEM simulation is also reported.

scholarly journals 3D-FEM Simulation of Hot Rolling Process and Characterization of the Resultant Microstructure of a Light-Weight Mn Steel

Crystals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 569
Author(s):  
Ana Claudia González-Castillo ◽  
José de Jesús Cruz-Rivera ◽  
Mitsuo Osvaldo Ramos-Azpeitia ◽  
Pedro Garnica-González ◽  
Carlos Gamaliel Garay-Reyes ◽  
...  
Keyword(s):  
Hot Rolling ◽  
Thermomechanical Processing ◽  
Computational Simulation ◽  
Effective Strain ◽  
Fem Simulation ◽  
Rolling Process ◽  
3D Fem ◽  
Hot Rolling Process ◽  
Mn Steel

Computational simulation has become more important in the design of thermomechanical processing since it allows the optimization of associated parameters such as temperature, stresses, strains and phase transformations. This work presents the results of the three-dimensional Finite Element Method (FEM) simulation of the hot rolling process of a medium Mn steel using DEFORM-3D software. Temperature and effective strain distribution in the surface and center of the sheet were analyzed for different rolling passes; also the change in damage factor was evaluated. According to the hot rolling simulation results, experimental hot rolling parameters were established in order to obtain the desired microstructure avoiding the presence of ferrite precipitation during the process. The microstructural characterization of the hot rolled steel was carried out using optical microscopy (OM), scanning electron microscopy (SEM) and X-ray diffraction (XRD). It was found that the phases present in the steel after hot rolling are austenite and α′-martensite. Additionally, to understand the mechanical behavior, tensile tests were performed and concluded that this new steel can be catalogued in the third automotive generation.

Enhanced Vibration Control of Ultrasonic Tooling Using Finite Element Analysis

1991 ◽  
Author(s):  
Kevin O’Shea
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Cross Sections ◽  
High Frequency ◽  
Excellent Correlation ◽  
Accurate Identification ◽  
Element Analysis ◽  
Optimum Configuration ◽  
Slot Length ◽  
Design Variables

Abstract The use of finite element analysis (FEA) in high frequency (20–40 kHz), high power ultrasonics to date has been limited. Of paramount importance to the performance of ultrasonic tooling (horns) is the accurate identification of pertinent modeshapes and frequencies. Ideally, the ultrasonic horn will vibrate in a purely axial mode with a uniform amplitude of vibration. However, spurious resonances can couple with this fundamental resonance and alter the axial vibration. This effect becomes more pronounced for ultrasonic tools with larger cross-sections. The current study examines a 4.5″ × 6″ cross-section titanium horn which is designed to resonate axially at 20 kHz. Modeshapes and frequencies from 17–23 kHz are examined experimentally and using finite element analysis. The effect of design variables — slot length, slot width, and number of slots — on modeshapes and frequency spacing is shown. An optimum configuration based on the finite element results is prescribed. The computed results are compared with actual prototype data. Excellent correlation between analytical and experimental data is found.

scholarly journals Reflection and transmission of high-frequency acoustic, electromagnetic and elastic waves at a distinguished class of irregular, curved boundaries

2019 ◽  
Vol 84 (6) ◽  
pp. 1203-1219
Author(s):  
Anthony Radjen ◽  
Gabriele Gradoni ◽  
Richard Tew
Keyword(s):  
High Frequency ◽  
Two Dimensions ◽  
Wave Number ◽  
Small Scale ◽  
Linear Wave ◽  
Incoming Wave ◽  
Reflection And Transmission ◽  
Large Wave ◽  
Irregular Boundary ◽  
Arbitrary Profile

Abstract Reflection and transmission phenomena associated with high-frequency linear wave incidence on irregular boundaries between adjacent acoustic or electromagnetic media, or upon the irregular free surface of a semi-infinite elastic solid, are studied in two dimensions. Here, an ‘irregular’ boundary is one for which small-scale undulations of an arbitrary profile are superimposed upon an underlying, smooth curve (which also has an arbitrary profile), with the length scale of the perturbation being prescribed in terms of a certain inverse power of the large wave-number of the incoming wave field. Whether or not the incident field has planar or cylindrical wave-fronts, the associated phase in both cases is linear in the wave-number, but the presence of the boundary irregularity implies the necessity of extra terms, involving fractional powers of the wave-number in the phase of the reflected and transmitted fields. It turns out that there is a unique perturbation scaling for which precisely one extra term in the phase is needed and hence for which a description in terms of a Friedlander–Keller ray expansion in the form as originally presented is appropriate, and these define a ‘distinguished’ class of perturbed boundaries and are the subject of the current paper.

Conservative Finite-Difference Scheme for High-Frequency Acoustic Waves Propagating at an Interface Between Two Media

2012 ◽  
Vol 11 (2) ◽  
pp. 351-366
Author(s):  
J. Staudacher ◽  
É Savin
Keyword(s):  
Phase Space ◽  
Acoustic Waves ◽  
High Frequency ◽  
Numerical Scheme ◽  
Propagation Model ◽  
Uniform Grid ◽  
Two Dimensional ◽  
Reflection And Transmission ◽  
Conservative Finite Difference Scheme ◽  
Homogeneous Media

AbstractThis paper is an introduction to a conservative, positive numerical scheme which takes into account the phenomena of reflection and transmission of high frequency acoustic waves at a straight interface between two homogeneous media. Explicit forms of the interpolation coefficients for reflected and transmitted wave vectors on a two-dimensional uniform grid are derived. The propagation model is a Liouville transport equation solved in phase space.

Oscillating Mechanics by Vector Graphics Means to Explain Phase Balanceable Principle Basing on Tri-Port Oscillator

2014 ◽  
Vol 886 ◽  
pp. 398-401
Author(s):  
Wei Zhou Hou ◽  
Juan Ling Wang
Keyword(s):  
Phase Equilibrium ◽  
High Frequency ◽  
Equilibrium Conditions ◽  
Vector Graphics ◽  
Balance Condition

During studying tri-port oscillator in oscillating mechanics high-frequency circuit, we proposed a straight forward method named "vector graphics means" to explain this constitute oscillating mechanics principle. When the oscillating mechanics circuit meet tri-port oscillator amplitude balance condition, "emitter same and other electrode-reverse" becomes a principle to determine whether the composition of the phase equilibrium conditions are satisfied.

A Novel Approach for the CAM-Follower Mechanism of High Frequency Cutting File Machine

2013 ◽  
Vol 333-335 ◽  
pp. 2085-2088
Author(s):  
Eurico Seabra ◽  
Hélder Puga ◽  
Luis Ferreira Da Silva
Keyword(s):  
External Force ◽  
High Frequency ◽  
Classical Mechanic ◽  
Virtual Model ◽  
Cam Mechanism ◽  
Novel Approach ◽  
Commercial Package ◽  
Cam Follower ◽  
Motion Characteristics ◽  
Positive Return

In this work, the re-design of the camfollower mechanism of an industrial cutting file machine is presented. The actual mechanical system includes a forceclosure cam mechanism, which requires an external force to keep the contact between the cam and the follower provided by a spring. This system is substituted by a new cam mechanism of the type of formclosure, which does not require external force. The formclosure camfollower mechanism, also called positive-return cam mechanism, guarantees that the cam surface is always in contact with the follower surface, and is characterized by having constantbreadth. Classical Mechanic Theory performs the study of the kinematic and dynamic characteristics of the cam mechanism analyzed throughout this work. Furthermore, a commercial package software was used to create a virtual model and analyze the motion characteristics of the new cam mechanism.

scholarly journals Practical use of High-Resolution 20 MHz Ultrasonography in Dermatovenerology

2016 ◽  
Vol 16 (3) ◽  
pp. 22-31
Author(s):  
A Kozarova ◽  
E Minarikova ◽  
T Pappova
Keyword(s):  
High Frequency ◽  
Visual Information ◽  
Diagnostic Procedure ◽  
Skin Diseases ◽  
Invasive Procedure ◽  
Thickness Measurement ◽  
Imaging Method ◽  
Excellent Correlation ◽  
Skin Tumours ◽  
Non Invasive

Abstract High-frequency skin ultrasonography using Dermascan C, manufactured by Cortex Technology, is an important part of modern diagnostic procedure of various skin diseases. It has been used in dermatology since 1979, when it was first used for the measurement of cutaneous thickness. Ultrasonography is a universal, painless, low-risk and non-invasive procedure that can easily be performed and repeated. It provides real-time visual information about the processes in the skin. This technique has grown to become frequent imaging method in dermatology. Skin ultrasonography is usually applied in the assessment of skin tumours, inflammatory or fibrosing skin diseases. The main application of ultrasonography in dermatovenerology is a preoperative thickness measurement of malignant melanoma. There is an excellent correlation between ultrasonographic and histological measurements of melanomas thickness. Moreover, information about the lesion quality and the inner structure can be obtained. In this article authors present the possibility of using high-frequency 20 MHz ultrasonography in dermatovenerology.

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