scholarly journals Thermal Noise in Cubic Optical Cavities

Photonics ◽  
2021 ◽  
Vol 8 (7) ◽  
pp. 261
Author(s):  
Guanjun Xu ◽  
Dongdong Jiao ◽  
Long Chen ◽  
Linbo Zhang ◽  
Ruifang Dong ◽  
...  
Keyword(s):  
Finite Element ◽  
Thermal Noise ◽  
Compressive Force ◽  
Frequency Instability ◽  
Fused Silica ◽  
Element Analysis ◽  
Optical Cavities ◽  
Fluctuation Dissipation ◽  
Fluctuation Dissipation Theorem ◽  
Analytic Estimate

Thermal noise in optical cavities sets a fundamental limit to the frequency instability of ultra-stable lasers. Numata et al. derived three equations based on strain energy and the fluctuation–dissipation theorem to estimate the thermal noise contributions of the spacer, substrates, and coating. These equations work well for cylindrical cavities. Extending from that, an expression for the thermal noise for a cubic spacer based on the fluctuation–dissipation theorem is derived, and the thermal noise in cubic optical cavities is investigated in detail by theoretical analysis and finite element simulation. The result shows that the thermal noise of the analytic estimate fits well with that of finite element analysis. Meanwhile, the influence of the compressive force Fp on the thermal noise in cubic optical cavities is analyzed for the first time. For a 50 mm long ultra-low expansion cubic cavity with fused silica substrates and GaAs/AlGaAs crystalline coating, the displacement noise contributed from every Fp of 100 N is about three times more than that of the substrate and coating.

Biomechanical Study of Lumbar Spine (L2-L4) Using Hybrid Stabilization Device - A Finite Element Analysis

2020 ◽  
Vol 10 (1) ◽  
pp. 20-32 ◽  
Author(s):  
Pushpdant Jain ◽  
Mohammed Rajik Khan
Keyword(s):  
Finite Element ◽  
Compressive Force ◽  
Element Model ◽  
Biomechanical Study ◽  
Bottom Surface ◽  
Element Analysis ◽  
Axial Compressive Force ◽  
Hybrid Stabilization ◽  
Flexion Extension ◽  
Lumbar Segment

Spinal instrumentations have been designed to alleviate lower back pain and stabilize the spinal segments. The present work aims to evaluate the biomechanical effect of the proposed Hybrid Stabilization Device (HSD). Non-linear finite element model of lumbar segment L2-L4 were developed to compare the intact spine (IS) with rigid implant (RI) and hybrid stabilization device. To restrict all directional motion vertebra L4 bottom surface were kept fixed and axial compressive force of 500N with a moment of 10Nm were applied to the top surface of L2 vertebrae. The results of range of motion (ROM), intervertebral disc (IVD) pressure and strains for IVD-23 and IVD-34 were determined for flexion, extension, lateral bending and axial twist. Results demonstrated that ROM of HSD model is higher than RI and lower as compared to IS model. The predicted biomechanical parameters of the present work may be considered before clinical implementations of any implants.

scholarly journals Dynamic Finite Element Analysis of Bending-Torsion Coupled Beams Subjected to Combined Axial Load and End Moment

2015 ◽  
Vol 2015 ◽  
pp. 1-12 ◽  
Author(s):  
Mir Tahmaseb Kashani ◽  
Supun Jayasinghe ◽  
Seyed M. Hashemi
Keyword(s):  
Finite Element ◽  
Convergence Rates ◽  
Nonlinear Eigenvalue Problem ◽  
Analytical Data ◽  
Compressive Force ◽  
Weighted Residual Method ◽  
Element Analysis ◽  
Closed Form Solutions ◽  
Dynamic Finite Element ◽  
Coupled Beams

The dynamic analysis of prestressed, bending-torsion coupled beams is revisited. The axially loaded beam is assumed to be slender, isotropic, homogeneous, and linearly elastic, exhibiting coupled flexural-torsional displacement caused by the end moment. Based on the Euler-Bernoulli bending and St. Venant torsion beam theories, the vibration and stability of such beams are explored. Using the closed-form solutions of the uncoupled portions of the governing equations as the basis functions of approximation space, the dynamic, frequency-dependent, interpolation functions are developed, which are then used in conjunction with the weighted residual method to develop the Dynamic Finite Element (DFE) of the system. Having implemented the DFE in a MATLAB-based code, the resulting nonlinear eigenvalue problem is then solved to determine the coupled natural frequencies of illustrative beam examples, subjected to various boundary and load conditions. The proposed method is validated against limited available experimental and analytical data, those obtained from an in-house conventional Finite Element Method (FEM) code and FEM-based commercial software (ANSYS). In comparison with FEM, the DFE exhibits higher convergence rates and in the absence of end moment it produces exact results. Buckling analysis is also carried out to determine the critical end moment and compressive force for various load combinations.

Study on Design of Metallic Sandwish Structure and its Mechanical and Thermal Properties

2013 ◽  
Vol 461 ◽  
pp. 85-94
Author(s):  
Rui Qiao ◽  
Ce Guo ◽  
Chun Sheng Zhu ◽  
Zhen Dong Dai ◽  
Xiao Ting Jiang
Keyword(s):  
Finite Element ◽  
Compressive Force ◽  
Fem Analysis ◽  
Displacement Curve ◽  
Mechanical And Thermal Properties ◽  
Stainless Steel Sheet ◽  
Metallic Structure ◽  
Element Analysis ◽  
Static Experiment ◽  
Force Displacement

Based on the microstructure of the beetles elytras cross-section, a bio-inspired metallic structure was designed. The mechanical property and the thermal property of the structure were analyzed with finite element method, and the compressive force-displacement curve and temperature distribution the structure were obtained, respectively. At the same time, the bio-inspired metallic structure sample was made with the material of the stainless steel sheet, and the quasi-static experiment and the thermal experiment of the structure were carried out. Comparing the experimental results with the FEM analysis, the results proved both the accuracy and reliability of FEM. Key words:beetle elytra;microstructure;bio-inspired structure; finite element analysis

scholarly journals Indentation densification of fused silica assessed by raman spectroscopy and constitutive finite element analysis

2020 ◽  
Vol 103 (5) ◽  
pp. 3076-3088 ◽  
Author(s):  
Sebastian Bruns ◽  
Tobias Uesbeck ◽  
Sindy Fuhrmann ◽  
Mariona Tarragó Aymerich ◽  
Lothar Wondraczek ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Raman Spectroscopy ◽  
Finite Element ◽  
Fused Silica ◽  
Element Analysis

THEORETICAL AND FINITE ELEMENT ANALYSIS TO DETERMINE CONTACT PRESSURE, VONMISSES STRESSES AND WEAR IN CAM AND FOLLOWER FOR VARIOUS CAM ROTATIONAL ANGLES IN IC ENGINE

2019 ◽  
Vol 14 (2) ◽  
Author(s):  
Jayakumar K ◽  
Aldrin Raj J ◽  
Somesh Subramanian S
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Contact Pressure ◽  
Compressive Force ◽  
Surface Wear ◽  
Hertz Contact ◽  
Element Analysis ◽  
Ic Engine ◽  
Rotational Angle ◽  
Base Circle

The contact between the cam and follower that exists in the valve strain system of IC engine influences wear. The dynamic analysis of cam and follower system in carried to find the normal compressive force for various cam rotational angles. Based on this compressive force on the cam, the hertz contact stresses and surface wear are calculated theoretically. Finite element analysis was carried out in the three critical portions of the cam such as cam nose region, cam tangent region and cam base circle region to compare the results. The results showed that cam rotational angle directly affects the contact pressure. The max contact pressure occurs in the nose end of the cam. The results showed that principle stress and wear also increases with cam rotational angle

Fabrication of Deep Cup with Flange by In-Plane Stretch Forming Applying Compressive Force in Thickness Direction

2016 ◽  
Vol 716 ◽  
pp. 897-906 ◽  
Author(s):  
Shohei Kajikawa ◽  
Takashi Iizuka ◽  
Takashi Kuboki
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Wall Thickness ◽  
Material Flow ◽  
Compressive Force ◽  
Side Wall ◽  
Thickness Direction ◽  
Stretch Forming ◽  
Element Analysis

This paper presents a new stretch forming method that applies compressive force for forming a deep cup with a flange. In this method, a punch and a die having a hole are used, and the main parameters are the depth of the die hole, ddh, and the clearance between the punch and the die, c. The effect of ddh and c was investigated by using an aluminum blank of thickness 2 mm in an experiment and a finite element analysis (FEA). When ddh was too small, the material flow could not be controlled appropriately, and when ddh was too large, a local thinning occurred during initial stretching into the die hole. When c was set at large, the side wall thickness of the formed cup was uneven, but a deep cup could be obtained by setting c below a half of the blank thickness. As a result, a deep cup of height 8.3 mm and with a flange was formed successfully under the condition that ddh was 1.5 mm and c was 0.5 mm.

scholarly journals Dynamic finite element analysis of bending-torsion coupled beams subjected to combined axial load and end moment

2021 ◽  
Author(s):  
Mir Tahmaseb Kashani ◽  
Supun Jayasinghe ◽  
Seyed M. Hashemi
Keyword(s):  
Finite Element ◽  
Convergence Rates ◽  
Nonlinear Eigenvalue Problem ◽  
Analytical Data ◽  
Compressive Force ◽  
Weighted Residual Method ◽  
Element Analysis ◽  
Closed Form Solutions ◽  
Dynamic Finite Element ◽  
Coupled Beams

The dynamic analysis of prestressed, bending-torsion coupled beams is revisited. The axially loaded beam is assumed to be slender, isotropic, homogeneous, and linearly elastic, exhibiting coupled flexural-torsional displacement caused by the end moment. Based on the Euler-Bernoulli bending and St. Venant torsion beam theories, the vibration and stability of such beams are explored. Using the closed-form solutions of the uncoupled portions of the governing equations as the basis functions of approximation space, the dynamic, frequency-dependent, interpolation functions are developed, which are then used in conjunction with the weighted residual method to develop the Dynamic Finite Element (DFE) of the system. Having implemented the DFE in a MATLAB based code, the resulting nonlinear eigenvalue problem is then solved to determine the coupled natural frequencies of illustrative beam examples, subjected to various boundary and load conditions. The proposed method is validated against limited available experimental and analytical data, those obtained from an in-house conventional Finite Element Method (FEM) code and FEMbased commercial software (ANSYS). In comparison with FEM, the DFE exhibits higher convergence rates and in the absence of end moment it produces exact results. Buckling analysis is also carried out to determine the critical end moment and compressive force for various load combinations.

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