scholarly journals Analysis of dynamics of a vertical cantilever in rotary coupling to the moving frame with movement limiters

2018 ◽  
Vol 241 ◽  
pp. 01021
Author(s):  
Piotr Wolszczak ◽  
Grzegorz Litak ◽  
Krystian Lygas
Keyword(s):  
Mechanical Energy ◽  
Elastic Beam ◽  
Beam Deflection ◽  
Moving Frame ◽  
Nonlinear Phenomena ◽  
Horizontal Distance ◽  
Energy Effect ◽  
Cross Sectional ◽  
Excitation Beam ◽  
Analysis Of Dynamics

The efficiency of the mechanical energy harvesting with the use of vibrating elements can be improved by synchronizing stimulation vibrations and own linear frequencies of systems as well as super or sub harmonics induced by non-linear phenomena. The article presents numerical cross-sectional study of the mechanical system. The system consists of an elastic beam set vertically, which the lower end is fixed in the rotary support, and is stimulated to move in the horizontal axis. The upper end of the beam is free but below its level there are bumpers limiting the free rotation of the beam. Numerical studies took into account the variability of the frequency and amplitude of the excitation beam movement, and horizontal distance between bumpers. Beam deflection was observed, on the basis of which the amount of energy generated by the piezo element was estimated. Nonlinear phenomena and analysis of frequency synchronization of vibrations improving the energy effect of an energy generator are presented.

Capillary Force Induced Elastic Deformation on ZnS Nanobeams

2011 ◽  
Author(s):  
Xinnan Wang ◽  
Xiaodong Li
Keyword(s):  
Electron Microscope ◽  
Surface Energy ◽  
Total Energy ◽  
Elastic Deformation ◽  
Capillary Force ◽  
Elastic Beam ◽  
Small Strain ◽  
Beam Deflection ◽  
Atomic Force ◽  
Transmission Electron

In this study, synthesized Wurtzite-structured ZnS nanobelts was investigated using high resolution transmission electron microscope, atomic force microscope, and scanning electron microscope for structural and morphology analyses. Results show that ZnS nanobelts are tens of microns in length, mostly ∼40×50 nm2 in width and thickness. The nanobelts grow along direction [001] and are dislocation free. The distance spacing for (001) plane is 3.19A˚. The capillary force was found strong enough to deform the ZnS nanobeam down to the substrate. Theoretical analysis on small strain elastic deformation was conducted. It was found that as the maximum beam deflection increases, beam elastic energy increases; in the meantime, the surface energy decreases. The net increase in elastic beam energy is less than the net decrease in the surface energy, resulting in total energy decrease. In addition, as the volume of liquid increases, for a certain maximum beam deflection, the total energy increases, this is result of the increase of the surface energy. Furthermore, for a specific nanobeam to be deflected to the underlying surface, the amount of liquid can be calculated.

Nonlinear Dynamic Modeling of Elastic Beam Fixed on a Moving Cart and Carrying Lumped Tip Mass Subjected to External Periodic Force

2009 ◽  
Author(s):  
Fadi A. Ghaith
Keyword(s):  
Linear Model ◽  
Equations Of Motion ◽  
Elastic Beam ◽  
Open Loop ◽  
Beam Deflection ◽  
Mode Shapes ◽  
Euler Beam ◽  
Periodic Force ◽  
Assumed Mode Method ◽  
Tip Mass

In the present work, a Bernoulli – Euler beam fixed on a moving cart and carrying lumped tip mass subjected to external periodic force is considered. Such a model could describe the motion of structures like forklift vehicles or ladder cars that carry heavy loads and military airplane wings with storage loads on their span. The nonlinear equations of motion which describe the global motion as well as the vibration motion were derived using Lagrangian approach under the inextensibility condition. In order to investigate the influence of the axial movement of the cart on the response of the system, unconstrained modal analysis has been carried out, and accurate mode shapes of the beam deflection were obtained. The assumed mode method was utilized for approximating the beam elastic deformation based on the single unconstrained mode shapes. Numerical simulation has been carried out to estimate the open-loop response of the nonlinear beam-mass-cart model as well as for the simplified linear model under the influence of the periodic excitation force. Also a comparison study between the responses of the linear and nonlinear models was established. It was shown that the maximum values of the beam tip deflection estimated from the nonlinear model are lower than the corresponding values obtained via the linear model, which reveals the importance of considering nonlinear hardening term in formulating the equations of motion for such system in order to come with more accurate and reliable model.

Velocity Field and Energy Dissipation in Viscoplastic Flow in Tubes of Non-Circular Cross-Section

2014 ◽  
Author(s):  
Mario F. Letelier ◽  
Dennis A. Siginer ◽  
Felipe Godoy
Keyword(s):  
Energy Dissipation ◽  
Velocity Field ◽  
Yield Stress ◽  
Cross Section ◽  
Mechanical Energy ◽  
Longitudinal Velocity ◽  
Circular Cross Section ◽  
Viscoplastic Flow ◽  
Entire Cross Section ◽  
Cross Sectional

An analytical method for determining the velocity field, shear stress and energy dissipation in viscoplastic flow in non-circular straight tubes is presented. Bingham’s model of fluid is used for the case of tubes with several cross-sectional contours that can be arbitrarily chosen through a shape factor imposed in the solution for the longitudinal velocity. The analysis is extended to steady flow in tubes in which the cross-section contour exhibits sharp corners. In these cases three flow zones are distinguished: stagnant, non-zero deformation, and plug zones. The method provides the expressions for determining the boundaries and characteristics of those three zones for a wide variety of cross-section shapes. In particular the dynamics of plug-zones for large values of the yield stress and for contours that markedly differ from circumferences is analyzed. Energy dissipation is determined throughout the entire cross-section, so that the effect of shape on mechanical energy loss is assessed in terms of the yield stress and viscosity of the fluid. Some general expressions that help understand energy dissipation mechanisms are derived by using natural coordinates for the velocity field and related variables. These results draw on several recent works from other researchers and the present authors, which have highlighted the significant difficulty of determining the zones of zero deformation in viscoplastic flow when the related solid boundaries are not elementary.

scholarly journals HUBUNGAN ANTARA GANGGUAN PENDENGARAN DENGAN SERUMEN PADA LANSIA DI PUSKESMAS MEDAN JOHOR

2019 ◽  
Vol 1 (2) ◽  
pp. 41-47
Author(s):  
Alamsyah Lukito
Keyword(s):  
Hearing Loss ◽  
Mechanical Energy ◽  
Electrical Energy ◽  
Ear Canal ◽  
Cross Sectional ◽  
Hearing Organ ◽  
Human Ear ◽  
The Brain

The human ear is a hearing organ that captures and changes sound in the form of mechanical energy into electrical energy efficiently and is passed on to the brain to be realized and understood. Serum that collects and forms masses will clog the ear canal, causing interference with the sound that results in hearing loss. The research that will be conducted is a study with a cross-sectional method with a sample of 52 people. The majority of respondents were men with a majority of elderly with an average age of 67 years. The results showed that respondents who had serumen were as much as 59.6% and those who had hearing loss were 63.5%. This shows that there is a relationship between hearing loss and the presence of serumen.

scholarly journals Analytical Solution for the Boundary Value Problem of Elastic Beams Subjected to Distributed Load

2021 ◽  
Vol 17 (1) ◽  
pp. 75-93
Author(s):  
Mustapha Adewale Usman ◽  
Nur Nabilah Afja Mohd Afandi ◽  
Fatai Akangbe Hammed ◽  
Debora Oluwatobi Daniel
Keyword(s):  
Differential Equation ◽  
Analytical Solution ◽  
Boundary Value Problem ◽  
Moving Load ◽  
Boundary Value ◽  
Elastic Beam ◽  
Beam Deflection ◽  
Elastic Beams ◽  
Distributed Load ◽  
Order Four

Analytical solution for the boundary value problem (BVP) of elastic beams subjected to distributed load was investigated. Based on the study, dynamic application curves are developed for beam deflection. The partial differential equation of order four were analysed to determine the dynamic response of the elastic beam under consideration and solved analytically. Effects of different parameters such as the mass of the load, the length of the moving load, the distance covered by the moving load, the speed of the moving and the axial force were considered. Result revealed that the values of the deflection with acceleration being considered are higher than the system where acceleration of the moving load is negligible. These obtained results are in agreement with the existing results.

Inspiring Learning: Assessment of Friction in a Real-World Model Using the Moving Frame Method in Dynamics

2018 ◽  
Author(s):  
Thorstein R. Rykkje ◽  
Daniel Leinebø ◽  
Erlend Sande Bergaas ◽  
Andreas Skjelde ◽  
Thomas J. Impelluso
Keyword(s):  
Undergraduate Students ◽  
Virtual Work ◽  
3D Visualization ◽  
Mechanical Energy ◽  
Rigid Bodies ◽  
Moving Frame ◽  
Integration Scheme ◽  
Moving Frames ◽  
Moving Frame Method ◽  
Frame Method

This project conducts research in energy dissipation. It also demonstrates the power of the new Moving Frame Method (MFM) in dynamics to inspire undergraduate students to embark on research in engineering. The MFM is founded on Lie Group Theory to model rotations of objects, Cartan’s moving frames to model the change of a frame in terms of the frame, and a new notation from the discipline of geometrical physics. The MFM presents a consistent notation for single bodies, linked systems and robotics. This work demonstrates that this new method is accessible by undergraduate students. The MFM structures the equations of motion on the Special Euclidean Group and the Principle of Virtual work. A restriction on the virtual angular velocities to enable variational methods empowers the method. This work implements an explicit fourth order Runge-Kutta numerical integration scheme. It assesses the change in mechanical energy. In addition, this work researches the energy losses due to friction in a system of linked rigid bodies. This research also builds the physical hardware and compares the theory and experiment using 3D visualization. The authors built the structure to observe the actual motion and approximate the energy loss functions. This project demonstrates the power of WebGL to supplement analyses with visualization.

On the Mechanics of Pipewalking: Case of a Buried Pipeline

2010 ◽  
Author(s):  
Vincent O. S. Olunloyo ◽  
Charles A. Osheku ◽  
Adekunle O. Adelaja
Keyword(s):  
Temperature Variation ◽  
Nonlinear Partial Differential Equations ◽  
Soil Layer ◽  
Elastic Beam ◽  
Beam Theory ◽  
Integral Transforms ◽  
Fluid Temperature ◽  
Cross Sectional ◽  
Longitudinal Modes ◽  
Internal Fluid

The influence of soil sedimentation on the pipe walking phenomenon is investigated analytically via a set of coupled nonlinear partial differential equations where the effects of operating variables such as internal fluid temperature variation, prestress and internal pressurization, Coriolis and axial accelerations of the internal fluid and cross sectional area change are fully captured. For this problem, a segment of an offshore pipeline resting on the ocean floor is idealized as elastic beam on an elastic foundation using recently refined Euler-Bernoulli beam theory. By invoking integral transforms, closed form analytical expressions for displacement of the fluid-pipe-soil interaction system associated with pipe walking is computed. Simulated results showed that pipe walking phenomenon is strongly dependent on sedimentation level, friction at the interface of pipe-ocean sub soil layer, temperature variation, fluctuations in internal fluid pressurisation and oscillatory strain of the pipe in both transverse and longitudinal modes.

Systematic Error in the Measure of Microdamage by Modulus Degradation During Four-Point Bending Fatigue

2007 ◽  
Author(s):  
Matthew D. Landrigan ◽  
Ryan K. Roeder
Keyword(s):  
Fatigue Testing ◽  
Elastic Beam ◽  
Beam Theory ◽  
Maximum Load ◽  
Beam Deflection ◽  
Linear Elastic ◽  
Four Point Bending ◽  
Specimen Width ◽  
Initial Modulus ◽  
Specimen Height

The accumulation of fatigue damage in bovine and human cortical bone is conventionally measured by modulus or stiffness degradation. The initial modulus or stiffness of each specimen is typically measured in order to normalize tissue heterogeneity to a prescribed strain [1,2]. Cyclic preloading at 100 N for 20 cycles has been used for this purpose in both uniaxial tension and four-point bending tests [1–3]. In four-point bending, the specimen modulus is often calculated using linear elastic beam theory as, (1)E=3Fl4bh2ε where F is the applied load, l is the outer support span, b is the specimen width, h is the specimen height, and ε is the maximum strain based on the beam deflection [2]. The maximum load and displacement data from preloading is used to determine the initial specimen modulus. The initial modulus and a prescribed maximum initial strain are then used to determine an appropriate load for fatigue testing under load control.

Modeling cycling performance: Effects of saddle position and cadence on cycle pedaling efficiency

2021 ◽  
Vol 104 (4) ◽  
pp. 003685042110414
Author(s):  
JongRok Lee ◽  
Kiwon Park
Keyword(s):  
Energy Conservation ◽  
Experimental Method ◽  
Mechanical Energy ◽  
Effective Means ◽  
Experimental Studies ◽  
Cycling Performance ◽  
Horizontal Distance ◽  
Knee Angle ◽  
Performance Effects ◽  
Optimal Cadence

The modeling method is an effective means of estimating causality as well as examining cycle pedaling efficiency. Pedaling efficiency can also be examined by an experimental method, but the experimental method can lead to contradictory results due to perturbation of the measured output parameters. Experimental studies generally yield realistic results, but it is difficult to control for all the variables of interest and to determine the causal relationships between them. The objective of this study is to investigate the pedaling efficiency and causality with considering saddle position and pedaling cadence as variables. Based on the mathematical pedaling modeling, the internal work calculation method was used to calculate the consumed mechanical energy and energy conservation percentage ([Formula: see text]). The optimal saddle position with the lowest mechanical energy and the highest energy conservation percentage could be changed by the cadence. At the low cadence, the higher saddle position, and the shorter horizontal distance between the saddle and crankshaft led to higher pedaling efficiency ( h: 0.95 m, d: 0.16 m, and knee angle: [Formula: see text]). However, the highest pedaling efficiency was achieved at the high cadence with a saddle height ( h) of 0.9 m and a horizontal distance between the saddle and the crankshaft ( d) of 0.06 m (knee angle: [Formula: see text]). The lowest cadence is the optimal cadence in terms of the consumed energy, but the optimal cadence was 90 r/min in terms of the energy conservation percentage. Compared to the energy consumption, the energy conservation percentage was demonstrated to influence the fatigue of a cycle rider more critically. The energy conservation percentage was highest at 90 r/min, and 90 r/min was close to the preferred cadence by the cyclist.

Design and Experiment of the Frictional Sensor for Underground Structure Monitoring

2014 ◽  
Vol 578-579 ◽  
pp. 1012-1015
Author(s):  
Jian Wang ◽  
Wei Ping Lian ◽  
Hui Hua
Keyword(s):  
Frictional Force ◽  
Soil Structure ◽  
Mechanical Response ◽  
Underground Structure ◽  
Elastic Beam ◽  
Beam Deflection ◽  
Axial Deformation ◽  
Transverse Deformation ◽  
Soil Pressure ◽  
Structure Monitoring

A type of frictional sensor which can be applied to measure the frictional force between soil and underground structure is invented. The key part of the senor is an elastic beam which has very small axial deformation under axial force but has much larger transverse deformation under same transverse forces, and the frictional force is calculated from the beam deflection. The advantage of the sensor is that it can be easily produced and it has very clear mechanical response under frictional force. Numerical analysis and experiments show that the frictional sensor is stable with high resolution. Moreover, it is almost not influenced by soil pressure normal to the soil-structure interface.

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