Size-Dependent Vibration Analysis of FG Microbeams in Thermal Environment Based on Modified Couple Stress Theory

Jalali, Mohammad Hadi; Zargar, Omid Ali; Baghani, Mostafa

doi:10.1007/s40997-018-0193-6

Cited by 31 publications

(10 citation statements)

References 35 publications

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“…However, the linearly varying term in Equation can cause the magnitude of macroscopic thermal stresses to increase with increasing depth as shown by the z =3 cm and z =5 cm cases in Figure for D =10 cm and P =103 hr. Furthermore, since the linearly varying term reverses sign with depth, this causes part of the rock to be in tension and part to be in compression (as shown in Figure ), which may be thought of as being analogous to bending‐induced normal stresses in beams (Jalali, Zargar, & Baghani, ).…”

Section: Effect Of Diurnal Temperature Variations and Gradients On Thmentioning

confidence: 99%

Unraveling the Mechanics of Thermal Stress Weathering: Rate‐Effects, Size‐Effects, and Scaling Laws

et al. 2019

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Thermal stress weathering is now recognized to be an active and significant geomorphological process on airless bodies. This study aims to understand the key factors governing thermal stresses in rocks on airless bodies through extensive numerical calculations and analytic analyses. Microscopic (grain‐scale) thermal stresses are driven primarily by the maximum diurnal temperature variation at said depth. Macroscopic (rock‐scale) thermal stresses are more complex. For rock sizes larger than the thermal skin depth, macroscopic thermal stresses are driven primarily by second (and higher) order spatial gradients of temperature. For rock sizes smaller than the thermal skin depth, macroscopic thermal stresses are primarily driven by the ratio of rock size to thermal skin depth. Additionally, scaling relations for diurnal surface temperature variation, time‐rate‐of‐change of surface temperature, as well as peak microscopic (grain‐scale) and macroscopic (rock‐scale) thermal stresses are derived to provide a more accessible modeling tool. These scaling relations are remarkably accurate when compared to both the numerical calculations as well as three‐dimensional finite element calculations. The model formulation, results, and scaling relations provided here allow the estimation of diurnal temperatures and thermal stresses on rocks of various size and materials on airless bodies at any orbital distance with a broad spectrum of spin rates. Lastly, we postulate and confirm that there is a critical spin rate where macroscopic thermal stresses will be greatest.

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Section: Effect Of Diurnal Temperature Variations and Gradients On Thmentioning

confidence: 99%

Unraveling the Mechanics of Thermal Stress Weathering: Rate‐Effects, Size‐Effects, and Scaling Laws

et al. 2019

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“…Although this technique is very convenient and it seems very capable for simple models with only a few degrees of freedom, but it cannot be suitable for intricate models, and its main drawback is the difficulty in interpreting the difference in the two models. Therefore, using a reasonable mathematical criterion is very helpful [34,35].…”

Section: Resultsmentioning

confidence: 99%

A New Conceptual Modelling Method for Vehicle Subframe to Evaluate Dynamic Performance of Structures at Conceptual Design Stage

Azaripour

Masoumi

2019

IJAME

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In recent years, the reduction of noise and vibrations caused by the road or internal components of vehicles have been a significant factor in the satisfaction and comfort of the occupants of cars. Therefore, to minimize these vibrations, the dynamic behaviour of the components of the vehicle should be considered in detail to reduce their level by setting useful parameters on structures. Nowadays, the conceptual model method can be regarded as a suitable alternative to the fundamental sophisticated computational techniques in measuring the vibration of vehicle components. Accordingly, the advanced finite element (FE) model examined for the subframe structure under the vehicle engine, and its conceptual model is developed by the one-dimensional beam elements to justify the dynamic behaviour of the subframe. The results of the experiments in the laboratory as well as the advanced subframe model are adapted, and the integrity of the natural frequencies and the mode shapes at low frequencies represented comprehensively. The result of the subframe concept model compared to the experimental model and computer-aided-engineering (CAE) model showed that the modal assurance criterion (MAC) is above 0.75 for the first four mode shapes of subframe structure and is above 0.9 for first and fourth mode shapes, and also the error percentage of natural frequency is lower than 8%. Therefore, for the analysis of the subframe performance in noise, vibration, and harshness (NVH) domain, the presented model could be considered in the conceptual phase design to reduce the solution time significantly.

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“…Furthermore, they introduced Bree's Diagram to more effectively plot the material behavior of thick-walled cylinders under different loading conditions and were able to identify safe loading boundary for different temperatures and pressures. Jalali et al [32] studied mechanical analysis of micro FG beams considering thermal conditions using a numerical method to see the effect of temperature change in natural frequencies of FG micro beams. The effects of thermal conductivity, temperature change, heat wave speed, heat flux, CNTs volume fraction and end support conditions on the nonlinear vibration of beam were discussed in detail by Pourasghar and Chen [33].…”

Section: Introductionmentioning

confidence: 99%

Graphene and CNT impact on heat transfer response of nanocomposite cylinders

Behdinan

Moradi‐Dastjerdi

Safaei

et al. 2020

Nanotechnology Reviews

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AbstractReinforcing polymers with nanofillers is an advanced approach to improve and manage the thermal behaviors of polymeric nanocomposite materials. Among the proposed nanofillers, graphene and carbon nanotube (CNT) with superior thermal conductivity are two advanced nanofillers, which have extensively been utilized to enhance the heat transfer responses of host polymeric materials. In this work, the impacts of randomly oriented graphene and CNT to steady state and transient heat transfer behaviors of functionally graded (FG) nanocomposite cylinders have been investigated using an axisymmetric model. Nanocomposite cylinders have been assumed to be under heat fluxes, heat convections or temperatures as different types of thermal boundary conditions. The thermal properties of the resulted nanocomposite materials are estimated by micromechanical model. Moreover, the governing thermal equations of axisymmetric cylinders have been analyzed using a highly consistent and reliable developed mesh-free method. This numerical method predicts temperature fields via MLS shape functions and imposes essential boundary conditions with transformation approach. The effects of nanofiller content and distribution as well as thermal boundary conditions on the heat transfer responses of nanocomposite cylinders are studied. The results indicated that the use of nanofiller resulted in shorter stationary times and higher temperature gradients in FG nanocomposite cylinders. Moreover, the use of graphene in nanocomposites had stronger impact on thermal response than CNT.

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Size-Dependent Vibration Analysis of FG Microbeams in Thermal Environment Based on Modified Couple Stress Theory

Cited by 31 publications

References 35 publications

Unraveling the Mechanics of Thermal Stress Weathering: Rate‐Effects, Size‐Effects, and Scaling Laws

Unraveling the Mechanics of Thermal Stress Weathering: Rate‐Effects, Size‐Effects, and Scaling Laws

A New Conceptual Modelling Method for Vehicle Subframe to Evaluate Dynamic Performance of Structures at Conceptual Design Stage

Graphene and CNT impact on heat transfer response of nanocomposite cylinders

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