scholarly journals INVESTIGATION OF RESIDUAL STRESSES AND DEFORMATIONS OF A PULTRUDED THIN BEAM PROFILE

2021 ◽  
Vol 3 ◽  
pp. 232-235
Author(s):  
Endija Namsone
Keyword(s):  
Chemical Analysis ◽  
Residual Stresses ◽  
Epoxy Resin ◽  
Glass Fibre ◽  
Mechanical Analysis ◽  
Beam Profile ◽  
Degree Of Cure ◽  
Thin Beam ◽  
Linear Elastic ◽  
Applied Approach

In the present study, a coupled 3D transient thermo-chemical analysis together with 2D plane strain mechanical analysis is carried out for the pultrusion process. For the mechanical analysis, a cure hardening instantaneous linear elastic (CHILE) approach is used of a thin beam profile made of glass fibre and epoxy resin. The applied approach is efficient and fast to investigate the residual stresses and deformations together with the distributions of temperature and degree of cure obtained from the thermo-chemical analysis. 

Viscoelastic behavior of an epoxy resin during cure below the glass transition temperature: Characterization and modeling

2018 ◽  
Vol 53 (2) ◽  
pp. 155-171 ◽  
Author(s):  
Alice Courtois ◽  
Martin Hirsekorn ◽  
Maria Benavente ◽  
Agathe Jaillon ◽  
Lionel Marcin ◽  
...  
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Epoxy Resin ◽  
Viscoelastic Behavior ◽  
Mechanical Analysis ◽  
Strain History ◽  
Model Parameters ◽  
Degree Of Cure ◽  
Model Predictions

This paper presents a viscoelastic temperature- and degree-of-cure-dependent constitutive model for an epoxy resin. Multi-temperature relaxation tests on fully and partially cured rectangular epoxy specimens were conducted in a dynamic mechanical analysis apparatus with a three-point bending clamp. Master curves were constructed from the relaxation test results based on the time–temperature superposition hypothesis. The influence of the degree of cure was included through the cure-dependent glass transition temperature which was used as reference temperature for the shift factors. The model parameters were optimized by minimization of the differences between the model predictions and the experimental data. The model predictions were successfully validated against an independent creep-like strain history over which the temperature varied.

Effect of degree of cure on viscoplastic shear strain development in layers of [45/−45]s glass fibre/ epoxy resin composites

2018 ◽  
Vol 52 (24) ◽  
pp. 3277-3288 ◽  
Author(s):  
Liva Pupure ◽  
Sibin Saseendran ◽  
Janis Varna ◽  
Margherita Basso
Keyword(s):  
Epoxy Resin ◽  
Shear Strain ◽  
Glass Fibre ◽  
Final Phase ◽  
Strain Development ◽  
Degree Of Cure ◽  
Residual Stress State ◽  
Viscoelastic Strain ◽  
Applied Shear Stress ◽  
Observed Behaviour

Effect of degree of cure on irreversible (viscoplastic) shear strain development in layers of glass fibre/ epoxy resin (LY5052 epoxy resin) [+45 °/−45 °]s laminate is studied performing a sequence of constant stress creep and viscoelastic strain recovery tests. For fixed values of degree of cure in range from 79.7% to 100%, the viscoplastic strains were measured as dependent on time and stress and Zapa's integral representation was used to characterize the observed behaviour. It is shown that at all degrees of cure the viscoplastic behaviour can be described by Zapa's model with parameters dependent on degree of cure. It is shown that for degree of cure lower than 80% the viscoplastic strains grow much faster and are much more sensitive to the increase of the applied shear stress. These irreversible strains developing in the final phase of the curing can significantly alter the residual stress state in the composite structure.

scholarly journals Numerical aspects for efficient welding computational mechanics

2014 ◽  
Vol 18 (suppl.1) ◽  
pp. 139-148
Author(s):  
Tarek Aburuga ◽  
Aleksandar Sedmak ◽  
Zoran Radakovic
Keyword(s):  
Residual Stresses ◽  
Three Dimensional ◽  
Shell Element ◽  
Element Model ◽  
Mechanical Analysis ◽  
Tensile Test Specimen ◽  
Integrity Assessment ◽  
Mass Scaling ◽  
Three Dimensional Models ◽  
Thermal Mechanical Analysis

The effect of the residual stresses and strains is one of the most important parameter in the structure integrity assessment. A finite element model is constructed in order to simulate the multi passes mismatched submerged arc welding SAW which used in the welded tensile test specimen. Sequentially coupled thermal mechanical analysis is done by using ABAQUS software for calculating the residual stresses and distortion due to welding. In this work, three main issues were studied in order to reduce the time consuming during welding simulation which is the major problem in the computational welding mechanics (CWM). The first issue is dimensionality of the problem. Both two- and three-dimensional models are constructed for the same analysis type, shell element for two dimension simulation shows good performance comparing with brick element. The conventional method to calculate residual stress is by using implicit scheme that because of the welding and cooling time is relatively high. In this work, the author shows that it could use the explicit scheme with the mass scaling technique, and time consuming during the analysis will be reduced very efficiently. By using this new technique, it will be possible to simulate relatively large three dimensional structures.

Thermomechanical Model of Spot Welding for Calculating Residual Stresses

2003 ◽  
Author(s):  
Lijun Xu ◽  
Jamil A. Khan
Keyword(s):  
Residual Stresses ◽  
Heat Generation ◽  
Spot Welding ◽  
Welding Process ◽  
Mechanical Analysis ◽  
Temperature Dependent ◽  
Thermomechanical Model ◽  
Faying Surface ◽  
Proposed Model ◽  
Electrode Interface

A comprehensive axisymmetric model of the coupled thermal-electrical-mechanical analysis predicting weld nugget development and residual stresses for the resistance spot welding process of Al-alloys is developed. The model estimates the heat generation at the faying surface, the workpiece-electrode interface, and the Joule heating of the workpiece and electrode. The phase change due to melting in the weld pool is considered. The contact area and its pressure distribution at both the faying surface and the electrode-workpiece interface are determined from a coupled thermal-mechanical model using a finite element method. The knowledge of the interface pressure provides accurate prediction of the interfacial heat generation. For the numerical model, temperature dependent thermal, electrical and mechanical properties are used. The proposed model can successfidly calculate the nugget diameter and thickness, and predict the residual stresses and the elastic-plastic deformation history. The calculated nugget shape and the deformation of sheets based on the model are compared with the experimental data. The computed residual stresses approach the distribution of experimental measurement of the residual stress.

Influence of the Interface and Residual Stresses on the Apparent Fracture Toughness of Layered Ceramic Composites Based on Alumina-Zirconia

2014 ◽  
Vol 606 ◽  
pp. 209-212
Author(s):  
Luboš Náhlík ◽  
Bohuslav Máša ◽  
Pavel Hutař
Keyword(s):  
Residual Stresses ◽  
Crack Propagation ◽  
Ceramic Composites ◽  
Layered Composites ◽  
Material Interfaces ◽  
Linear Elastic ◽  
Apparent Fracture Toughness ◽  
Elastic Fracture ◽  
Layered Ceramic ◽  
Good Agreement

This paper deals with the fracture behaviour of layered ceramic composite with residual stresses. The main goal is to investigate the effect of residual stresses and material interfaces on crack propagation by more complex 3D finite element models. The crack behaviour was described by analytical procedures based on linear elastic fracture mechanics (LEFM) and generalized LEFM. The influence of laminate composition with residual stresses on critical values for crack propagation through the laminate interfaces was also determined. Good agreement has been found to exist between numerical results and experimental data. The results obtained can be used for a design of new layered composites with improved resistance against crack propagation.

Orthotropic Characteristics of Glass-Fibre-Epoxy Laminates under Plane Stress

1973 ◽  
Vol 15 (2) ◽  
pp. 102-108 ◽  
Author(s):  
R. M. Ogorkiewicz
Keyword(s):  
Tensile Strength ◽  
Epoxy Resin ◽  
Uniaxial Tension ◽  
Plane Stress ◽  
Glass Fibre ◽  
Orthotropic Material ◽  
Glass Fibres ◽  
Degree Of Anisotropy

Deformational characteristics of laminates of unidirectionally arranged glass fibres and epoxy resin under plane stress are shown to correspond very closely under uniaxial tension and, to a lesser extent, under shear to the theroetical pattern of stiffness of an orthotropic material. The anisotropy in stiffness is also shown to be accompanied by an even greater degree of anisotropy in tensile strength.

scholarly journals The magnetic mechanical analysis of manganese steel

1921 ◽  
Vol 98 (692) ◽  
pp. 297-302 ◽  
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Magnetic Properties ◽  
Chemical Analysis ◽  
Cold Water ◽  
Mechanical Analysis ◽  
Magnetic Behaviour ◽  
Manganese Steel

One of the most interesting alloys for the study of its magnetic properties is manganese steel. The following paper is an attempt to correlate some of the magnetic and mechanical properties of manganese steel, in the hope that as such data are circulated it will eventually be possible to interpret from the magnetic behaviour of steel what the mechanical properties will be. Six manganese steel rods supplied by one of the authors were drawn from the same source, 76 cm. long and 0·95 cm. in diameter, and used “as drawn.” These rods were marked 1, 2, 3, 4, 5, and 6 respectively. The chemical analysis was made on rod No. 4 and showed:— C................................1.25 per cent. Si................................ 0.43 „ Mn...............................12.20 „ The record for the heat treatment was as follows:—“ All six bars were treated at 1000° C. (five minutes), and then water-quenched in ordinary cold water. Nos. 1, 5 and 6 were then enclosed in an iron pipe welded over at the ends, and annealed. The time for cooling from 550° C. to 450° C. was about eight hours. As this treatment did not make the bars sufficiently magnetic they were again annealed at 500° C. (530° C.—475° C.) for sixty hours."

Innovative technologies in corrosion-resistant coatings development aimed at ship navigation equipment protection

2021 ◽  
Vol 103 (3) ◽  
pp. 5-12
Author(s):  
Oleh Bezbakh
Keyword(s):  
Residual Stresses ◽  
Epoxy Resin ◽  
Epoxy Matrix ◽  
Phthalic Acid ◽  
Epoxy Oligomer ◽  
Acid Anhydride ◽  
Molecular Formula ◽  
Innovative Technologies ◽  
Composite Formation ◽  
The Matrix

The efficient use of some innovative technologies in adhesives with advanced operational characteristics development aimed at anti-corrosion properties increase of transport means has been substantiated in the paper under discussion. The above-mentioned technologies involving the use of some interaction-active ingredients forming the cross-linkable coatings composition, including some polymers, have provided their cohesion properties essential improvement. Epoxy diane oligomer ED-16 has been chosen as the main component for the matrix in the composite formation. The aliphatic resin DЕG-1 (GOST 10136-77) as a plasticizer has been added to the epoxy oligomer. The compound has been formed of the following concentration: epoxy resin ED-16: plasticizer DЕG -1 – 100: 40. The hardener of cold hardening polyethelenepolyamine PEPA (ТУ 6-05-241-202-78) has been used at the epoxy resin-based developed materials polymerization. Phthalic acid anhydride has been used as a modifier to improve the properties of epoxy composite materials. The modifier was added to the matrix in the following ratio: from 0,10 to 2,00 pts.wt. per 100 pts.wt. of epoxy oligomer ЕD-20. The molecular formula of the modifier is as follows: C8H4O3. Molar mass is 148,1 g/mol. Density is ρ = 1,52 г/см³. To form a composite material or a protective coating with some improved adhesive properties and inconsiderable residual stresses the phthalic acid anhydride as a modifier was found to be added to the epoxy matrix with the content q = 1,25 pts.wt. per 100 pts.wt. of the epoxy matrix (oligomer ЕD-20 + plasticizer DЕG -1). In this case, the adhesive strength of the coating is being increased from sа = 28,3 MPа to sа = 46,4 MPа, and residual stresses – from sз = 1,9 MPа to sз = 2,1 MPа. First of all, the improved properties of the modified materials were caused by the interaction of active carbonyl (С=О) groups of the modifier with nitrogen-containing (NH-) groups of the hardener. It has provided the increase of the composite cross-linking degree resulted in their both adhesive and cohesion properties improvement. Moreover, it was found that the modifier use in the compound with the content q = 1,0…1,5 00 pts.wt. per 100 00 pts.wt. of the matrix has provided the increase of the river water influenced coatings resistance from ρ = 12,1 Оm·cm2 до ρ = 21,2…22,4 Оm·cm2. Though, some further increase of the additive content in the coating has caused the deterioration of anti-corrosion characteristics of the materials. Thus, the conducted study has contributed to the determination of the most efficient content ratio of phthalic acid anhydride as a modifier to for the coatings of functional use.

Sign in / Sign up

Export Citation Format

Share Document