Static analysis of co-cured composite structures with double-layer damping membranes embedded

2020 ◽  
Vol 39 (17-18) ◽  
pp. 665-678
Author(s):  
Shaoqing Wang ◽  
Sen Liang ◽  
Changsheng Zheng ◽  
Yanchun Zhai ◽  
Yangyang Yan
Keyword(s):  
Double Layer ◽  
Composite Structures ◽  
Strain Energy ◽  
Stress Component ◽  
Present Formulation ◽  
The Finite Element Method ◽  
Sine Series ◽  
Fourier Sine Series ◽  
Parametric Studies ◽  
The Individual

The purpose of this study is to determine the effects of various parameters on the deflection value and strain energy for the individual stress of a co-cured composite structure with double-layer damping membranes embedded (CCSDDME) simply supported on four edges. To achieve this goal, an analytical solution (double Fourier sine series) was developed for the deflection of an embedded co-cured damping composite plate with double-layer damping membranes embedded. The deflection value and strain energy of each stress component are deduced. The present formulation is validated based on the results obtained using the finite element method and parametric studies are then carried out to illustrate the effects of various parameters on the deflection value and strain energy for an individual stress of CCSDDME.

scholarly journals Structural optimization to maximize loss factor of embedded co-cured damping composite

2019 ◽  
Vol 11 (11) ◽  
pp. 168781401989212
Author(s):  
Shaoqing Wang ◽  
Sen Liang ◽  
Qiang Li
Keyword(s):  
Loss Factor ◽  
Strain Energy ◽  
Stress Component ◽  
Ritz Method ◽  
Present Formulation ◽  
Total Thickness ◽  
The Finite Element Method ◽  
Maximum Loss ◽  
Structure Thickness ◽  
Optimal Value

The purpose of this study is to obtain the maximum loss factor of the embedded co-cure damping composite structure with the boundary condition of four edges clamped. To achieve this goal, the strain energy of each stress component is deduced using the Ritz method, and the loss factor of the structure is calculated. The present formulation is validated based on the results obtained using the finite element method. Finally, the law of loss factor variation with the change in structure thickness and layup angle is obtained. The results obtained show that the loss factor of the structure increases as the thickness of the structure increases; when the total thickness of the structure is constant, the loss factor increases first and then decreases, and there is an optimal value for the design; the optimal lay angle is pi/4.

Stress Analysis of a Tire Under Vertical Load by a Finite Element Method

1977 ◽  
Vol 5 (2) ◽  
pp. 102-118 ◽  
Author(s):  
H. Kaga ◽  
K. Okamoto ◽  
Y. Tozawa
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Computer Program ◽  
Temperature Rise ◽  
Strain Energy ◽  
Internal Stresses ◽  
Vertical Load ◽  
The Finite Element Method ◽  
Internal Temperature ◽  
Element Method

Abstract An analysis by the finite element method and a related computer program is presented for an axisymmetric solid under asymmetric loads. Calculations are carried out on displacements and internal stresses and strains of a radial tire loaded on a road wheel of 600-mm diameter, a road wheel of 1707-mm diameter, and a flat plate. Agreement between calculated and experimental displacements and cord forces is quite satisfactory. The principal shear strain concentrates at the belt edge, and the strain energy increases with decreasing drum diameter. Tire temperature measurements show that the strain energy in the tire is closely related to the internal temperature rise.

scholarly journals Research on the Manufacturing Quality of Co-Cured Hat-Stiffened Composite Structure

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2747
Author(s):  
Xiangwen Ju ◽  
Jun Xiao ◽  
Dongli Wang ◽  
Cong Zhao ◽  
Xianfeng Wang
Keyword(s):  
Composite Structures ◽  
Sound Pressure ◽  
Integration Method ◽  
Complex Geometry ◽  
Sound Field ◽  
Thickness Measurement ◽  
Curing Process ◽  
The Finite Element Method ◽  
Manufacturing Quality

The stringer-stiffened structure is widely used due to its excellent mechanical properties. Improving the manufacturing quality of stringer-stiffened structure which have complex geometry is important to ensure the bearing capacity of aviation components. Herein, composite hat-stiffened composite structures were manufactured by different filling forms and bladders with various properties, the deformation of silicone rubber bladder in co-curing process was studied by using the finite element method. The thickness measurement at different positions of the hat-stiffened structure was performed to determine the best filling form and bladder property. Moreover, in view of the detection difficulties in R-zone of stringer, numerical simulation was performed to get the sound pressure and impulse response of at the R-zone of stringer by Rayleigh integration method, and an effective equipment which could stably detect the manufacturing quality of R-zone was designed to verify the correctness of sound field simulation and realize the detection of stringer. With the optimum filling form and bladder properties, hat-stiffened composites can be manufactured integrally with improved surface quality and geometric accuracy, based on co-curing process.

Mechanical characterization of a woven multi-layered hyperelastic composite laminate under uniaxial loading

2021 ◽  
pp. 002199832110115
Author(s):  
Shaikbepari Mohmmed Khajamoinuddin ◽  
Aritra Chatterjee ◽  
MR Bhat ◽  
Dineshkumar Harursampath ◽  
Namrata Gundiah
Keyword(s):  
Composite Materials ◽  
Energy Function ◽  
Strain Energy ◽  
Strain Energy Function ◽  
Mechanical Tests ◽  
Stress Strain ◽  
Aerospace Applications ◽  
Envelope Material ◽  
The Individual ◽  
High Dielectric

We characterize the material properties of a woven, multi-layered, hyperelastic composite that is useful as an envelope material for high-altitude stratospheric airships and in the design of other large structures. The composite was fabricated by sandwiching a polyaramid Nomex® core, with good tensile strength, between polyimide Kapton® films with high dielectric constant, and cured with epoxy using a vacuum bagging technique. Uniaxial mechanical tests were used to stretch the individual materials and the composite to failure in the longitudinal and transverse directions respectively. The experimental data for Kapton® were fit to a five-parameter Yeoh form of nonlinear, hyperelastic and isotropic constitutive model. Image analysis of the Nomex® sheets, obtained using scanning electron microscopy, demonstrate two families of symmetrically oriented fibers at 69.3°± 7.4° and 129°± 5.3°. Stress-strain results for Nomex® were fit to a nonlinear and orthotropic Holzapfel-Gasser-Ogden (HGO) hyperelastic model with two fiber families. We used a linear decomposition of the strain energy function for the composite, based on the individual strain energy functions for Kapton® and Nomex®, obtained using experimental results. A rule of mixtures approach, using volume fractions of individual constituents present in the composite during specimen fabrication, was used to formulate the strain energy function for the composite. Model results for the composite were in good agreement with experimental stress-strain data. Constitutive properties for woven composite materials, combining nonlinear elastic properties within a composite materials framework, are required in the design of laminated pretensioned structures for civil engineering and in aerospace applications.

Critical examination of various approaches used for analysing helical cables

1994 ◽  
Vol 29 (1) ◽  
pp. 43-55 ◽  
Author(s):  
M Raoof ◽  
I Kraincanic
Keyword(s):  
Large Diameter ◽  
Numerical Results ◽  
Hertzian Contact ◽  
Critical Examination ◽  
First Order ◽  
Wide Range ◽  
End Conditions ◽  
Parametric Studies ◽  
The Individual ◽  
Fixed End

Using theoretical parametric studies covering a wide range of cable (and wire) diameters and lay angles, the range of validity of various approaches used for analysing helical cables are critically examined. Numerical results strongly suggest that for multi-layered steel strands with small wire/cable diameter ratios, the bending and torsional stiffnesses of the individual wires may safely be ignored when calculating the 2 × 2 matrix for strand axial/torsional stiffnesses. However, such bending and torsional wire stiffnesses are shown to be first order parameters in analysing the overall axial and torsional stiffnesses of, say, seven wire stands, especially under free-fixed end conditions with respect to torsional movements. Interwire contact deformations are shown to be of great importance in evaluating the axial and torsional stiffnesses of large diameter multi-layered steel strands. Their importance diminishes as the number of wires associated with smaller diameter cables decreases. Using a modified version of a previously reported theoretical model for analysing multilayered instrumentation cables, the importance of allowing for the influence of contact deformations in compliant layers on cable overall characteristics such as axial or torsional stiffnesses is demonstrated by theoretical numerical results. In particular, non-Hertzian contact formulations are used to obtain the interlayer compliances in instrumentation cables in preference to a previously reported model employing Hertzian theory with its associated limitations.

Tunable Band Gaps of Acoustic Waves in Two-Dimensional Phononic Crystals With Reticular Band Structures

2009 ◽  
Author(s):  
Zi-Gui Huang ◽  
Yunn-Lin Hwang ◽  
Pei-Yu Wang ◽  
Yen-Chieh Mao
Keyword(s):  
Acoustic Waves ◽  
Composite Structures ◽  
Phononic Crystals ◽  
Band Gaps ◽  
Sound Insulation ◽  
Two Dimensional ◽  
The Finite Element Method ◽  
Elastic Band ◽  
Band Structures ◽  
Elastic Band Gaps

The excellent applications and researches of so-called photonic crystals raise the exciting researches of phononic crystals. By the analogy between photon and phonon, repetitive composite structures that are made up of different elastic materials can also prevent elastic waves of some certain frequencies from passing by, i.e., the frequency band gap features also exist in acoustic waves. In this paper, we present the results of the tunable band gaps of acoustic waves in two-dimensional phononic crystals with reticular band structures using the finite element method. Band gaps variations of the bulk modes due to different thickness and angles of reticular band structures are calculated and discussed. The results show that the total elastic band gaps for mixed polarization modes can be enlarged or reduced by adjusting the orientation of the reticular band structures. The phenomena of band gaps of elastic or acoustic waves can potentially be utilized for vibration-free, high-precision mechanical systems, and sound insulation.

A Two Step Damage Prognosis Method for Beam-Like Truss Structures

2014 ◽  
Vol 578-579 ◽  
pp. 1092-1095
Author(s):  
Hao Kai Jia ◽  
Ling Yu
Keyword(s):  
Finite Element Method ◽  
Strain Energy ◽  
Truss Structure ◽  
Truss Structures ◽  
Second Step ◽  
The Finite Element Method ◽  
Modal Strain Energy ◽  
Damage Prognosis ◽  
Modal Curvature ◽  
Simulation Results

In this study, a two step damage prognosis method is proposed for beam-like truss structures via combining modal curvature change (MCC) with modal strain energy change ratio (MSECR). Changes in the modal curvature and the elemental strain energy are selected as the indicator of damage prognosis. Different damage elements with different damage degrees are simulated. In the first step, the finite element method is used to model a beam-like truss structure and the displacement modes are got. The damage region is estimated by the MCC of top and bottom chords of a beam-like truss structure. In the second step, the elemental MSECR in the damage region is calculated and the maximum MSECR element is deemed as the damage element. The simulation results show that this method can accurately locate the damage in the beam-like truss structure.

Control of cracks by interfaces in composites

1975 ◽  
Vol 341 (1627) ◽  
pp. 409-428 ◽  
Keyword(s):  
Composite Material ◽  
Elastic Properties ◽  
Adhesive Joint ◽  
Composite Structures ◽  
Crack Path ◽  
Brittle Materials ◽  
Novel Theory ◽  
The Individual ◽  
Model Crack

A novel theory is proposed to show how a crack may he accelerated or retarded when it meets an interface between two equally brittle materials of different elastic properties. Measurements of a model crack travelling through a brittle adhesive joint have substantially verified the theory. The results demonstrate that the toughness of a composite material, having a periodic stiffness change along the crack path, may be very much greater than the toughness of the individual components of the composite. The relevance of these ideas to the design of tough composite structures is discussed.

Double Overhung Disk and Parameter Effect on Rotordynamic Synchronous Instability—Morton Effect—Part II: Occurrence and Prevention

2016 ◽  
Vol 139 (1) ◽  
Author(s):  
Xiaomeng Tong ◽  
Alan Palazzolo
Keyword(s):  
Transient Analysis ◽  
Operating Parameters ◽  
Flow Ratio ◽  
The Finite Element Method ◽  
Oil Viscosity ◽  
Testing Conditions ◽  
Bending Mode ◽  
Morton Effect ◽  
Nonlinear Transient ◽  
Parametric Studies

This paper performs the parametric studies corresponding with the theoretical Morton effect (ME) model explained in Part I of this paper, where the fully nonlinear transient analysis based on the finite element method is introduced. Operating parameters, such as oil supply temperature, bearing clearance, oil viscosity, etc., are perturbed from the testing conditions to investigate the shifting of critical speeds and ME instability onset speed (IOS). The ME is significantly affected by the rotor bending mode with large overhung deflections, and operating parameters should be adjusted to increase the separation margin between the operating speed and the corresponding critical speed for ME mitigation. Reducing the carryover flow ratio and using the asymmetric bearing pivot offset are capable to suppress the ME by reducing both the average and differential journal temperature. The heat barrier sleeve with air or ceramic isolation is designed to prevent the heat flux into the journal and can successfully mitigate the ME based on the simulations.

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