scholarly journals Numerical Analysis of Effect of Cohesive Parameters on Mixed-Mode Failure of Double-Scarf Adhesive Joint Subjected to Uniaxial Tensile Loadings

2015 ◽  
Author(s):  
Lijuan Liao ◽  
Chenguang Huang
Keyword(s):  
Adhesive Joint ◽  
Cohesive Zone ◽  
Adhesive Layer ◽  
Tensile Loading ◽  
Uniaxial Tensile ◽  
Mode I ◽  
Mode Ii ◽  
Adhesive Properties ◽  
Critical Fracture ◽  
Mode Failure

In the present study, the effects of cohesive parameters on the mixed-mode failure of double-scarf adhesive joint (DSAJ) subjected to uniaxial tensile loadings were examined and discussed numerically. For DSAJ with no perpendicular or parallel with the external loading direction, complex stress state (mixture of tensile and shear stresses) occurs at the adhesive interface. In addition, adhesive joint failure, which is a gradually process rather than a sudden transition, is accompanied by energy dissipates gradually at the crack tip. Correspondingly, cohesive zone model (CZM) coupled with finite element method (FEM) was implemented to verify the mechanism of crack from initiation to the complete failure. As the constitutive relation of the adhesive layer, the traction-separation (T-S) law determines the interface damage evolution. Additionally, the shape of T-S curves in mode I and mode II are crucially decided by the cohesive strengths and critical fracture energies in each mode, respectively. Firstly, the non-dimensional-normalized form of ultimate tensile loading of DSAJ was obtained using dimensional analysis. Then, three cases of cohesive parameters (case of constant anisotropy extent & case of constant critical fracture energy in each mode & case of constant cohesive strength in each mode) according to the non-dimensional-normalized form of adhesive properties were designed. Two types adhesives (brittle and ductile) were chosen to examine the effects of adhesive properties on the failure of DSAJ in this study. To avoid the influence of the geometries on DSAJ mechanical behaviors, the thickness of the adhesive layer and the scarf angle θ were held constantly, respectively. In numerical calculations, the change trends of the ultimate tensile loading (Fu), the failure energy (Ef) and the damage level (D) corresponding to Fu with respect to the cohesive parameters were discussed. It can be observed the cohesive strengths in mode I and mode II codetermine Fu of DSAJ with unequal rates. Moreover, Ef of DSAJ, which is the necessary energy for the joint failure, is governed by the critical fracture energies in mode I and mode II with different contributions. Besides, it also obtained that the evolutions of D corresponding to Fu of DSAJ with brittle and ductile adhesives are certain different. Generally, D of DSAJ with brittle adhesive is higher and more uneven than that of DSAJ with ductile adhesive. Accordingly, it can be concluded that DSAJ with brittle adhesive has lower ability to distribute the loading over a smaller cohesive zone with less uniform distribution. In addition, the numerical results revealed that with the increment of ratio in each case set in this paper, D of DSAJ does not rise obviously.

Adhesive Properties Subject to Temperature Testing for Cohesive Zone Modeling

2017 ◽  
Author(s):  
Nick Aerne ◽  
Taylor J. Rawlings ◽  
John P. Parmigiani
Keyword(s):  
Cantilever Beam ◽  
High Temperatures ◽  
Material Properties ◽  
Low Temperatures ◽  
Cohesive Zone ◽  
Cohesive Strength ◽  
Mode I ◽  
Mode Ii ◽  
Zone Model ◽  
Adhesive Properties

The growth of lightweight components and need for non-destructive fastening techniques leads to the use of adhesives in many industries. Modeling the behavior of adhesives in fastening joints can help in the design process to make an optimized joint, with minimal waste. However, in available material properties provided by manufactures of adhesives there is a gap in what is sufficient to accurately model and predict the behavior of real-world adhesive conditions. An adhesive joint may be loaded in mode I, mode II, mode III, or a combination of these in service. In components with outdoor application the ambient temperature outside in many regions can vary to below freezing to over 40 °C. The environmental conditions at these temperatures may influence the adhesive material properties. This body of research presents the results of adhesive properties subject to temperature testing. The needed material properties to compose an accurate model have been shown to be the mode I cohesive strength, mode I cohesive toughness, mode II cohesive strength, and mode II cohesive toughness. These properties can be measured with a test specimen designed to isolate that loading mode and condition. The specimens used are the Dog Bone Tensile Specimen (DBTS), the Double Cantilever Beam (DCB), Shear Loaded Dual Cantilever Beam (SLDCB), and Double Lap Shear (DLS). The effect of temperature will be tested by testing each specimen at −30°C, 20°C, and 45°C. Triplicates of each specimen at the respective temperature were tested. These results will be used in a cohesive zone model that will be validated with additional testing. The results from the two tested adhesives, Plexus MA832 and Pliogrip 7779/220, indicate these temperature conditions can change the cohesive strength in mode I by −60 to −40 % and mode II by −13 to 2% when at high temperatures (HT). The cohesive toughness in mode I by −40 to −20% and mode II by −40 to −2% when at high temperatures. The cohesive strength in mode I by −50 to 15% and mode II by 8% to 60% when at low temperatures (LT). The cohesive toughness in mode I by −70 to −20% and mode II by 30 to 60% when at low temperatures. As compared with those tested at room temperature (RT). The ranges here represent the response for both adhesives.

scholarly journals Thermal Delamination Modelling and Evaluation of Aluminium–Glass Fibre-Reinforced Polymer Hybrid

Polymers ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 492
Author(s):  
Zhen Pei Chow ◽  
Zaini Ahmad ◽  
King Jye Wong ◽  
Seyed Saeid Rahimian Koloor ◽  
Michal Petrů
Keyword(s):  
Crack Front ◽  
Cohesive Zone ◽  
Experimental Tests ◽  
Mode I ◽  
Mode Ii ◽  
Cohesive Model ◽  
Reinforced Polymer ◽  
Glass Fibre Reinforced Polymer ◽  
Fibre Reinforced Polymer ◽  
Glass Fibre Reinforced

This paper aims to propose a temperature-dependent cohesive model to predict the delamination of dissimilar metal–composite material hybrid under Mode-I and Mode-II delamination. Commercial nonlinear finite element (FE) code LS-DYNA was used to simulate the material and cohesive model of hybrid aluminium–glass fibre-reinforced polymer (GFRP) laminate. For an accurate representation of the Mode-I and Mode-II delamination between aluminium and GFRP laminates, cohesive zone modelling with bilinear traction separation law was implemented. Cohesive zone properties at different temperatures were obtained by applying trends of experimental results from double cantilever beam and end notched flexural tests. Results from experimental tests were compared with simulation results at 30, 70 and 110 °C to verify the validity of the model. Mode-I and Mode-II FE models compared to experimental tests show a good correlation of 5.73% and 7.26% discrepancy, respectively. Crack front stress distribution at 30 °C is characterised by a smooth gradual decrease in Mode-I stress from the centre to the edge of the specimen. At 70 °C, the entire crack front reaches the maximum Mode-I stress with the exception of much lower stress build-up at the specimen’s edge. On the other hand, the Mode-II stress increases progressively from the centre to the edge at 30 °C. At 70 °C, uniform low stress is built up along the crack front with the exception of significantly higher stress concentrated only at the free edge. At 110 °C, the stress distribution for both modes transforms back to the similar profile, as observed in the 30 °C case.

The Effect of Temperature, Thickness, and Working Time on Adhesive Properties

2018 ◽  
Author(s):  
Nicholas Aerne ◽  
John P. Parmigiani
Keyword(s):  
Cantilever Beam ◽  
Design Process ◽  
Working Time ◽  
Effect Of Temperature ◽  
Control Group ◽  
Mode I ◽  
Mode Ii ◽  
Adhesive Properties ◽  
Loading Modes ◽  
Mode Ii Loading

The need for lightweight components and non-destructive fastening techniques has led to the growth of adhesive use in many industries. Modeling the behavior of adhesives in fastening joints can help in the design process to make an optimized joint. To optimize joints in the design process, the loading conditions, environmental conditions of service, thickness of bond, and bonding procedures all need to be refined for the adhesive of interest. However, in available technical data sheets of adhesives provided by manufactures there is a gap in what is sufficient to accurately model and predict the behavior of real-world adhesive conditions. This body of research presents the results of the effects of temperature, thickness, and working time on adhesive properties. These effects can be observed with test specimens from the loading modes of interest. The loading modes of interest are mode I and mode II loading for the current study. The specimen for mode I loading is the Double Cantilever Beam, and for mode II loading is the Shear Loaded Dual Cantilever Beam. The effect of temperature will be tested by testing each specimen at −20°C, 20°C, and 40°C. Two bond thicknesses for adhesive thickness effects were tested. The working time had a control group bonded in the recommended working time and an expired working time group where the specimens were not joined until 10 minutes had passed from the recommended working time. Triplicates of each specimen at the respective conditions were tested. The adhesive selected for this research was Plexus MA832. The results of the experiment show that adhesive factors such as temperature, thickness, and working time can have degrading effects on adhesive performance in mode I and mode II.

scholarly journals Analysis on Failure Mechanism of Scarf Joints With Brittle-Ductile Adhesives Subjected to Uniaxial Tensile Loads

2013 ◽  
Author(s):  
Lijuan Liao ◽  
Toshiyuki Sawa ◽  
Chenguang Huang
Keyword(s):  
Failure Mechanism ◽  
Cohesive Zone ◽  
Cohesive Zone Model ◽  
Adhesive Layer ◽  
Uniaxial Tensile ◽  
Zone Model ◽  
Displacement Curve ◽  
Failure Energy ◽  
Complete Failure ◽  
Scarf Joints

The failure mechanism of scarf joints with a series of angles and brittle-ductile adhesives subjected to uniaxial tensile loads is analyzed by using a numerical method which employs a cohesive zone model (CZM) with a bilinear shape in mixed-mode (mode I and II). The adopted methodology is validated via comparisons between the present simulated results and the existing experimental measurements, which illustrate that the load-bearing capacity increases as the scarf angle decreases. More important, it is observed that the failure of the joint is governed by not only the ultimate tensile loads, but also the applied tensile displacement until complete failure, which is related to the brittle-ductile properties of the adhesive layer. In addition, failure energy, which is defined by using the area of the load-displacement curve of the joint, is adopted to estimate the joint strength. Subsequently, the numerical results show that the strength of the joint adopting ductile adhesive with higher failure energy is higher than that of the joint using brittle adhesive with lower failure energy.

Evaluation of Adhesive Properties Using Cohesive Zone Model : Mode I

2009 ◽  
Vol 33 (5) ◽  
pp. 474-481 ◽  
Author(s):  
Chan-Joo Lee ◽  
Sang-Kon Lee ◽  
Dae-Cheol Ko ◽  
Byung-Min Kim
Keyword(s):  
Cohesive Zone ◽  
Cohesive Zone Model ◽  
Mode I ◽  
Zone Model ◽  
Adhesive Properties

The Effect of Loading Mode on Fracture Toughness of Arcan Adhesive Joint

2015 ◽  
Vol 786 ◽  
pp. 3-7 ◽  
Author(s):  
Kevin Prakash ◽  
Khairul Salleh Basaruddin ◽  
Mohd Afendi Rojan ◽  
Haftirman Idrus
Keyword(s):  
Adhesive Joint ◽  
Mixed Mode ◽  
Initial Crack ◽  
Mode I ◽  
Mode Ii ◽  
Mixed Mode Loading ◽  
Fracture Test ◽  
Crack Line ◽  
Loading Mode ◽  
Adhesive Thickness

This paper presents the experimental investigation on adhesive joint under three loading angles using a modified Arcan jig. Fracture test was performed using the fabricated Arcan specimens and Araldite adhesive with loading angle of 0°, 90° and 45° to represent Mode I, Mode II and mixed Mode loading, respectively. Eighteen specimens were prepared with adhesive thickness of 6 mm and nine of them with interface crack length of 5 mm. The result shows the stress intensity factor, K is influenced by the loading angle and the initial crack-line directions. KI was found greater than KII .

scholarly journals Comparison of Tensile Strength and Fracture Toughness of Co-Bonded and Cold-Bonded Carbon Fiber Laminate-Aluminum Adhesive Joints

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 3778
Author(s):  
Fabrizio Moroni ◽  
Alessandro Pirondi ◽  
Chiara Pernechele ◽  
Luca Vescovi
Keyword(s):  
Fracture Toughness ◽  
Tensile Strength ◽  
Carbon Fiber ◽  
Adhesive Joint ◽  
Mode I ◽  
Mode Ii ◽  
Mode Ii Fracture ◽  
Fracture Tests ◽  
Peel Stress ◽  
Cold Bonding

The purpose of this work is to compare the co-bonding vs. cold-bonding route on the adhesive joint performance of a CFRP (Carbon Fiber Reinforced Polymer) laminate–aluminum connection. In particular, the overlap shear, tensile strength and Mode I and Mode II fracture toughness will be evaluated. The adhesives for co-bonding and cold-bonding are, respectively, a thermosetting modified epoxy, unsupported structural film and a two-component epoxy adhesive, chosen as representative of applications in the high-performance/race car field. The emerging trend is that, in tensile e Mode I fracture tests, the failure path is predominantly in the composite. Mode II fracture tests instead resulted in a cohesive fracture, meaning that, under pure shear loading, the weakest link may not be the composite. The lap-shear tests are placed midway (cohesive failure for co-bonding and composite delamination for cold-bonding, respectively), probably due to the different peel stress values related to the different adhesive Young’s modulus. The exploitation of the full capacity of the adhesive joint, hence the possibility of highlighting better, different performances of co-bonding vs. cold-bonding, would require consistent improvement of the out-of-plane strength of the CFRP laminate and/or to someway redistribute the peel stress on the bondline.

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