Parametric study on the influence of material properties and geometry on the thermally induced bistability of composite laminates

2021 ◽  
pp. 095440622110456
Author(s):  
Samir A Emam ◽  
Tarun Pherwani ◽  
Aravindh Anil ◽  
Aeman Muhammed
Keyword(s):  
Thermal Expansion ◽  
Aspect Ratio ◽  
Material Properties ◽  
Parametric Study ◽  
Composite Laminates ◽  
Thickness Ratio ◽  
Thermally Induced ◽  
Thermal Expansion Coefficients ◽  
Expansion Coefficients ◽  
Moduli Of Elasticity

This paper presents a parametric study on the key parameters that control the thermally induced bistability of cross-ply laminates. The influence of the material properties including the moduli of elasticity and the thermal expansion coefficients and the laminate’s geometry including the aspect ratio (AR) and the width-to-thickness ratio are investigated. The unsymmetric [Formula: see text] and the antisymmetric [Formula: see text] cross-ply laminates are investigated. Five key parameters are varied: the number of plies, the width-to-thickness ratio, the laminate’s aspect ratio, the ratio of the moduli of elasticity, and the ratio of the thermal expansion coefficients of the lamina. The laminate is assumed flat at the cured temperature and a uniform temperature gradient is applied until it is reduced to the room temperature. For each set of parameters, the stable equilibrium shapes of the laminate are obtained using a Ritz model. The ABAQUS finite element package is used to validate the model and an excellent agreement is obtained. Results that show the variation of the curvatures with the width-to-thickness ratio and the onset of the bistability for a variety of parameters are presented. The ratio of the moduli of elasticity and the thermal expansion coefficients significantly affect the critical width-to-thickness ratio at which the laminates become bistable. The unsymmetric laminates show bistability at a lower width-to-thickness ratio compared with the antisymmetric laminates. The results also show that the higher the aspect ratio, the lower the critical width-to-thickness ratio for stability for both laminates.

Thermal Stresses Under Engine Heat Flux—Part 1: Ceramic Coating on Metal Substrate

1992 ◽  
Vol 114 (4) ◽  
pp. 291-297 ◽  
Author(s):  
B. E. Sheets ◽  
K. Kokini
Keyword(s):  
Heat Flux ◽  
Thermal Expansion ◽  
Bond Coat ◽  
Thermal Stresses ◽  
Ceramic Coating ◽  
Metal Substrate ◽  
Thermal Expansion Coefficients ◽  
Expansion Coefficients ◽  
Edge Delamination ◽  
Moduli Of Elasticity

The thermal stresses in a ceramic coating bonded to a metal substrate generated by heat flux conditions in an engine were studied. Edge delamination of the coating was related to the displacements of an interface crack between the ceramic and the metal. The effects of varying the thermal expansion coefficients of the ceramic, the bond coat and the metal, thin moduli of elasticity, their thicknesses and the initial stress-free temperature were determined.

Thermal Expansion and Relaxation of W-Cu Multilayers

1992 ◽  
Vol 286 ◽  
Author(s):  
Wen-C. Chiang ◽  
Soo-Kil Kim ◽  
David V. Baxter
Keyword(s):  
Thermal Expansion ◽  
High Temperature ◽  
Heat Treatments ◽  
Irreversible Change ◽  
Thermally Induced ◽  
Temperature Range ◽  
Thermal Expansion Coefficients ◽  
Induced Stresses ◽  
Expansion Coefficients ◽  
Bulk Behavior

ABSTRACTWe have studied the structure of W-Cu multilayers with modulation wavelengths between 65 and 110 xsÅ over the temperature range 25-400° C. Using a high temperature diffractometer stage specifically designed for low angle work, thermal expansion coefficients were measured and found to be marginally greater than would be expected from bulk behavior even when interaction with the substrate is taken into account. Upon annealing at temperature as low as 180° C, increased intensity of the low angle superlattice peaks is observed. Heat treatments above 180° C result in an irreversible change in the multilayer associated with the migration of Cu atoms to cracks produced by thermally induced stresses.

Warm Compaction: FEM Analysis of Stress and Deformation States of Compacting Dies with Rectangular Profile of Various Aspect Ratio

2007 ◽  
Vol 534-536 ◽  
pp. 329-332
Author(s):  
Enrico Armentani ◽  
G.F. Bocchini ◽  
G. Cricrì ◽  
Renato Esposito
Keyword(s):  
Thermal Expansion ◽  
Aspect Ratio ◽  
Fem Analysis ◽  
Radial Pressure ◽  
Warm Compaction ◽  
Thermal Expansion Coefficients ◽  
Rectangular Profile ◽  
Die Profile ◽  
Expansion Coefficients ◽  
Stress And Deformation

The deformation under radial pressure of rectangular dies for metal powder compaction has been investigated by FEM. The explored variables have been: aspect ratio of die profile, ratio between diagonal of the profile and die height, insert and ring thickness, radius at die corners, interference, different insert materials, i. e. conventional HSS, HSS from powders, cemented carbide (10% Co). The analyses has ascertained the unwanted appearance of tensile normal stress on brittle materials, also “at rest”, and even some dramatic changes of stress patterns as the die height increases with respect to the rectangular profile dimensions. Different materials behave differently, mainly due to difference of thermal expansion coefficients. Profile changes occur when the dies are heated up to the temperature required for warm compaction. The deformation patterns depend on compaction temperature and on thermal expansion coefficients.

Thermal Expansion of GaN at Low Temperatures - a Comparison of Bulk and Homo- and Heteroepitaxial Layers

1999 ◽  
Vol 595 ◽  
Author(s):  
Verena Kirchner ◽  
Heidrun Heinke ◽  
Sven Einfeldt ◽  
Detlef Hommel ◽  
Jaroslaw Z. Domagala ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Low Temperatures ◽  
Lattice Mismatch ◽  
Thermal Strain ◽  
Chemical Vapor ◽  
Thermally Induced ◽  
Thermal Expansion Coefficients ◽  
Bulk Gan ◽  
Expansion Coefficients ◽  
Heteroepitaxial Layers

AbstractThe thermal expansion of different GaN samples is studied by high-resolution Xray diffraction within the temperature range of 10 to 600 K. GaN bulk crystals, a homoepitaxial layer and different heteroepitaxial layers grown by metalorganic chemical vapor deposition (MOCVD) and molecular beam epitaxy (MBE) were investigated. Below 100 K the thermal expansion coefficients (TEC) were found to be nearly zero which has to be taken into account when estimating the thermal strain of GaN layers in optical experiments commonly performed at low temperatures. The homoepitaxial layer and the underlying GaN substrate with a lattice mismatch of –6×10−4 showed identical thermal expansion. The comparison between the temperature behavior of lattice parameters of heteroepitaxial layers and bulk GaN points to a superposition of thermally induced biaxial strain and compressive hydrostatic strain.

scholarly journals Testing Contraction and Thermal Expansion Coefficient of Construction and Moulding Polymer Composites

2018 ◽  
Vol 25 (s1) ◽  
pp. 151-158 ◽  
Author(s):  
Łukasz Pyrzowski
Keyword(s):  
Thermal Expansion ◽  
Polymer Composites ◽  
Thermal Expansion Coefficient ◽  
Technological Process ◽  
Expansion Coefficient ◽  
Material Properties ◽  
Design Stage ◽  
Thermal Expansion Coefficients ◽  
Expansion Coefficients ◽  
Materials Used

Abstract The paper presents results of systematic tests of contraction and thermal expansion coefficients of materials based on polymer composites. The information on the above material properties is essential both at the design stage and during the use of finished products. Components for the samples were selected in such a way as to represent typical materials used for production of construction and moulding elements. The performed tests made it possible to monitor the analysed parameters at different stages of the technological process.

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