Numerical Analysis of the Bonded Composite Shape Effects under Thermal Loading in Aircraft Structures

2021 ◽  
Vol 1167 ◽  
pp. 1-11
Author(s):  
Achewek Azzouz ◽  
Rachid Mhamdia ◽  
Kacem Kaddouri ◽  
Djamila Benarbia
Keyword(s):  
Thermal Loading ◽  
Thermal Stresses ◽  
Adhesive Layer ◽  
Structural Safety ◽  
Cost Ratio ◽  
Geometrical Parameters ◽  
Initial Shape ◽  
Bonded Repair ◽  
Mechanical Performances ◽  
Two Parameters

The design of the optimal shape of patch with a good compromise between mechanical performances and manufacturing aspects can be sought in order to get the maximum structural safety-cost ratio. In this work an analysis has been conducted for development of a finite element methodology to circumvent the thermal effect problem in the bonded repair. Physical and geometrical parameters of the repair material were assumed to be variables, this method are based on two approaches: The first, have modified the patch shape by removing the two isosceles notches (h varied) for minimisation the heating size in the direction of loading. For the second step of the study, the same surface previously deduced are compensate in the other direction with varied the property module for the adhesive layer, for inducing a larger the area covering of crack tip and reduce the thermal stress. The values of thermal stresses obtained from the variation of these two parameters were found to be low compared to the obtained values for initial shape.

A Review of Temperature Reduction Methods in Codes and Standards for Pipe Supports

2020 ◽  
Author(s):  
Alex Mayes ◽  
Phillip Wiseman ◽  
Kshitij P. Gawande
Keyword(s):  
Heat Transfer ◽  
Computational Models ◽  
Thermal Stresses ◽  
Geometrical Parameters ◽  
Atmospheric Conditions ◽  
Closed Form Solutions ◽  
Temperature Reduction ◽  
Reduction Methods ◽  
American Society ◽  
Transient Thermal

Abstract American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code, Section III, Division 1, Subsection NF, Subparagraph NF-3121.11 does not require that thermal stresses in supports be evaluated. Historically, pipe support engineers have not been concerned with thermal stresses of pipe and component supports, but determining material temperature limits and allowable stresses have been a major role in designing and analyzing supports. Thus, heat transfer is often investigated in finding the temperature of pipe supports and parts of pipe supports that are not in direct contact with pipe or pipe components. There are also other Codes and standards that permit a reduction of temperature away from the outer surface of pipe or pipe components. In some but not all cases, Codes and standards explicitly address reduction of temperature for applications of utilizing thermal insulation. Additionally, the temperature distribution is established by specific geometrical parameters and their respective equations for employment by the pipe support engineer. These reductions are explored by utilizing fundamentals of heat transfer. Additionally, steady-state and transient thermal Finite Element Analyses (FEA) are used to establish computational models of simple geometric bodies in a range of atmospheric conditions. The effects of insulation on the thermal distribution are also represented through closed form solutions and FEA. The results of these analyses allow for assessment of, and recommendations for, the treatment of temperature reduction in Codes and standards.

Temperature-Dependent Vibration of Various Types of Sandwich Beams with Porous FGM Layers

2020 ◽  
pp. 2150016
Author(s):  
Mohsen Rahmani ◽  
Sajjad Dehghanpour
Keyword(s):  
Thermal Stresses ◽  
Equations Of Motion ◽  
Functionally Graded ◽  
Geometrical Parameters ◽  
Type I ◽  
Sandwich Beams ◽  
Temperature Dependent ◽  
The Core ◽  
Graded Layers ◽  
Lagrange Strain

By using a high order sandwich beams theory which is modified by considering the transverse flexibility of the core, free vibration characteristics of two models of sandwich beams are studied in this paper. In type-I, functionally graded layers coat a homogeneous core, and in type-II, an FG core is covered by homogeneous face sheets. To increase the accuracy of the model of the FGM properties, even and uneven porosity distributions are applied, and all materials are considered temperature-dependent. Nonlinear Lagrange strain and thermal stresses of the face sheets and in-plane strain of the core are considered. To obtain the governing equations of motion, Hamilton’s principle is used and a Galerkin method is used to solve them for simply supported and clamped boundary conditions. To verify the results of this study, they are compared with the results of literatures. Also, the effect of variation of temperature, some geometrical parameters and porosities on the frequency are studied.

scholarly journals Early-Age Properties of Concrete Based on Numerical Hydration Modelling: A Parametric Analysis

Materials ◽  
2020 ◽  
Vol 13 (9) ◽  
pp. 2112 ◽  
Author(s):  
Marco Pepe ◽  
Carmine Lima ◽  
Enzo Martinelli
Keyword(s):  
Parametric Analysis ◽  
Thermal Stresses ◽  
Cement Hydration ◽  
Concrete Strength ◽  
Numerical Procedure ◽  
Early Age ◽  
Concrete Element ◽  
Curing Conditions ◽  
Simplified Approach ◽  
Mechanical Performances

The early-age performances of cement-based mixtures are governed by cement hydration reactions. As a matter of fact, the heat generated during the setting and hardening phases due to the hydration processes increases the temperatures within the concrete elements while it starts developing its mechanical properties. These thermal stresses can cause the premature cracking of the cementitious matrix and undermine the long-term durability of the whole concrete element, especially in the case of massive structures where the dissipation of generated heat is more difficult. It is worth highlighting that the kinetics of cement hydration is mainly governed by the mixture composition; on the other hand, the heat generated during the setting and hardening is also influenced by the geometry of the element and/or its curing conditions. In this context, this study presents a numerical procedure intended to simulate the hydration reactions, and hence scrutinize the development of concrete properties at the early-age. Specifically, considering the variation of several factors, such as concrete strength class, element size and curing conditions, a comprehensive parametric analysis is presented herein, leading to the proposal of a simplified approach for both predicting the time evolution of the concrete mechanical performances at the early-age and mitigating the risk of premature cracking.

Weldment Analysis of a Diesel Engine Exhaust Manifold

2016 ◽  
Author(s):  
Masoud Mojtahed ◽  
Nganh Le ◽  
Jerry Wayne DeSoto
Keyword(s):  
Diesel Engine ◽  
Thermal Loading ◽  
Thermal Stresses ◽  
Engine Performance ◽  
Exhaust Manifold ◽  
Element Analysis ◽  
Performance Requirements ◽  
Pipe Model ◽  
Key Factor ◽  
Double Pipe

The Exhaust Manifold is an increasingly important component of industrial turbocharged diesel engines. It can be a key factor to increase the efficiency of any engine, in this case a power plant diesel engine. Analysis of the various structural and thermal loading of the liquid-cooled manifolds is of vital importance to increase the components efficiency and overall engine performance. In this analysis, problems such as thermal stress issues causing manifold failure are identified and redesigned to meet performance requirements and environmental regulations. These manifolds are of complicated shapes and contain many weld joints to attach several integral parts. The weld regions are identified to be sensitive to thermal stresses and most likely prone to failure. The welds were added to the model in ANSYS® Workbench. Computational Fluid Dynamics (Fluent) and Finite Element Analysis (FEA) were used to analyze the welded model. The main outcome was to understand the welds behavior using the ANSYS software and its powerful tools and to determine whether the areas containing welds are likely to fail under the given conditions. A simple double pipe model was also created and congruently analyzed to validate the results and the techniques used in analyzing the manifold model.

Buckling of Fibre-Reinforced Plastic-Steel Torispherical Shells Under External Pressure

1988 ◽  
Vol 202 (6) ◽  
pp. 409-420 ◽  
Author(s):  
G D Galletly ◽  
A Muc
Keyword(s):  
External Pressure ◽  
Experimental Results ◽  
Steel Shell ◽  
Elastic Buckling ◽  
Geometrical Parameters ◽  
Initial Shape ◽  
Buckling Modes ◽  
Reinforced Plastic ◽  
Composite Layers ◽  
Spherical Caps

The paper deals with the buckling of torispherical shells consisting of a steel external layer plus different numbers of composite layers. It is assumed that the total thickness of the fibre-reinforced plastic (FRP)-steel shell is constant but that the thickness of the steel and of the composite may be varied. In the paper it is shown (a) how the orientation of the fibres and the composite lamina thicknesses affect the elastic buckling modes and (b) how substantial increases in elastic buckling pressures may be achieved by reinforcing the steel torispheres with layers of composite. The analysis is carried out for various values of the geometrical parameters describing torispheres, including spherical caps. The influence of the yielding of the steel layer on the buckling pressures of FRP-steel torispheres is also discussed. As might be expected, it is necessary to take plasticity into account when predicting the buckling pressures of these shells. Some experimental results are given which confirm this expectation. The effect of initial shape imperfections in the shells is also considered briefly. However, the dearth of experimental results on FRP-steel shells prevents a proper evaluation of the way in which imperfections decrease their buckling strength.

Analysis of a Bow-Free Prestressed Test Specimen

2014 ◽  
Vol 81 (11) ◽  
Author(s):  
E. Suhir ◽  
J. Nicolics
Keyword(s):  
Cross Sections ◽  
Test Specimen ◽  
Thermal Loading ◽  
Thermal Stresses ◽  
Effective Means ◽  
Physical Nature ◽  
Accelerated Testing ◽  
Mode Shift ◽  
Temperature Range ◽  
Operation Conditions

Broadening the temperature range in accelerated testing of electronic products is a typical measure to assure that the product of interest is sufficiently robust. At the same time, a too broad temperature range can lead to the shift in the modes and mechanisms of failure, i.e., result in failures that will not occur in actual operation conditions. Application of mechanical prestressing of the test specimen could be an effective means for narrowing the temperature range during accelerated testing and thereby achieving trustworthy and failure-mode-shift-free accelerated test information. Accordingly, simple engineering predictive models are developed for the evaluation of the magnitude and the distribution of thermal and mechanical stresses in a prestressed bow-free test specimen. A design, in which an electronic or a photonic package is bonded between two identical substrates, is considered. Such a design is often employed in some today's packaging systems, in which the “inner,” functional, component containing active and/or passive devices and interconnects is placed between two identical “outer” components (substrates). The addressed stresses include normal stresses acting in the component cross sections and the interfacial shearing and peeling stresses. Although the specimen as a whole remains bow-free, the peeling stresses might be nevertheless appreciable, since the outer components, if thin enough, deflect to a greater or lesser extent with respect to the inner component. The numerical example has indicated that the maxima of the interfacial thermal shearing and peeling stresses are indeed comparable and that these maxima are on the same order of magnitude as the normal thermal stresses acting in the components' cross sections. It is shown that since the thermal and the prestressing mechanical loads are of different physical nature, the stresses caused by these two load categories are distributed differently over the specimen's length. It is shown also that although it is possible and even advisable to apply mechanical prestressing for a lower temperature range, it is impossible to reproduce the same stress distribution as in the case of thermal loading. The obtained results enable one to shed light on the physics of the state of stress in prestressed bow-free test specimens in electronics and photonics engineering.

Finite Element Analysis of Stiffness of Steel Plate with a Rectangular Cutout Bonded by Composite Patches

2013 ◽  
Vol 377 ◽  
pp. 3-7
Author(s):  
Ze Long You ◽  
Xiang Ming Zhang ◽  
Kui Du
Keyword(s):  
Finite Element ◽  
Steel Plate ◽  
Three Dimensional ◽  
Adhesive Layer ◽  
Shell Element ◽  
Element Model ◽  
Element Analysis ◽  
Spring Element ◽  
Bonded Repair ◽  
Spring Plate

An ANSYS-based "volume-spring-plate" three-dimensional finite element model is established in this paper to analyze steel plate with a rectangular hole reinforced by double-side bonding patch, in which the plate is simulated by solid45 8-node 3D element, the adhesive layer is simulated by linear elastic spring element combin14, and the patch is simulated by shell element. Relative intensity, relative stiffness and yield load rising rate of a patched steel plate with regard to parameters, such as the patch length, width, the number of patch layer and ply orientation are studied. The results indicate that composite bonded repair can effectively restore the mechanical properties of the structure and improve the service life.

Thermal stresses in a rotating, nonhomogeneous, anisotropic disk of varying thickness and density

1975 ◽  
Vol 10 (3) ◽  
pp. 137-142 ◽  
Author(s):  
G V Gurushankar
Keyword(s):  
Thermal Loading ◽  
Thermal Stresses ◽  
Closed Form Solution ◽  
Rotating Disk ◽  
Form Solution ◽  
Annular Disk ◽  
Varying Thickness ◽  
Principal Axes ◽  
Rotationally Symmetric ◽  
Anisotropic Disk

Closed form solution is obtained for stresses in a rotationally symmetric, nonhomogeneous, anisotropic, annular disk of varying thickness and density, subjected to thermal loading. Analysis is presented for a particular type of anisotropy, namely Polar Orthotropy, in which axes of anisotropy coincide with the principal axes of stresses at each point in the disk. The variations of homogenity, density and thickness are assumed to be hyperbolic. Numerical results in the form of graphs presented show the effect of nonhomogenity, density and degree of orthotropy on the stress distribution in a disk subjected to constant and varying temperature gradients. Homogeneous, varying density anisotropic rotating disk of varying thickness forms a special case of the analysis.

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