A Mixed Damage Model for Simulating Delamination of Composite T-Joint Components

2012 ◽  
Author(s):  
J. Chen
Keyword(s):  
Damage Model ◽  
Damage Effect ◽  
Damage Analysis ◽  
Test Results ◽  
Load Prediction ◽  
Damage Propagation ◽  
Cohesive Damage ◽  
Final Crack ◽  
Softening Stage ◽  
Good Agreement

A mixed cohesive damage model was introduced in this paper to study the delamination of composite T-joint components under pulling load. Prediction together with part of test results was presented in this paper. Modelling prediction had a good agreement with experimental work. This study indicated that the mixed damage scale plays an important role in the progressive damage analysis of T-joint components. The mixed damage scale properly reflected the effects of interaction between different damage modes in simulating damage propagation of an object with strong coupled effects. This coupled damage effect was considered from the material softening stage to final crack. Thus a proper damage accumulation was accounted since materials begin damage. An example given in this paper shown the delamination in the deltoid region of T-joint was simulated very well. Finally, a concept of novel materials was proposed for the deltoid region of T-joint in this paper. Initial investigation by simulating delamination presented that the damage resilience of composite T-joint with novel composite materials in deltoid region significantly improved its damage resilience.

A Computational Model for Fe Ductile Plastic Damage Analysis of Plate Bending

1993 ◽  
Vol 60 (3) ◽  
pp. 749-758 ◽  
Author(s):  
Guangyu Shi ◽  
G. Z. Voyiadjis
Keyword(s):  
Computational Model ◽  
Stiffness Matrix ◽  
Damage Model ◽  
Strain Energy Release ◽  
Elastic Stiffness ◽  
Yield Function ◽  
Damage Effect ◽  
Damage Analysis ◽  
Plastic Damage ◽  
Elastoplastic Damage

This paper presents a computational model for the finite element plastic damage analysis of ductile flexural plates. The phenomenological damage model proposed by Lemaitre is adopted here. The damage effect parameters of a cross-section are defined and employed to account for the damage effect across the thickness of a bending plate. Similar to the effective stresses used in many damage models, the effective stress couples are introduced in this work and used in the yield function. The damage criterion is defined in terms of damage strain energy release rates. Based on the damage node model proposed here, the elastoplastic-damage stiffness matrix of element is derived. When the corresponding elastic stiffness matrix is given explicitly, the resulting elastoplastic-damage stiffness matrix can be evaluated without use of numerical integration. The feature of the expicit form of element stiffness matrix makes the computational model proposed here very efficient. Several numerical examples of ductile plastic damage analysis of plates are also given in this work to demonstrate the validity of the computational model.

Evaluation of Water Flow on Interfacial Strength in PSA Film Delamination

2021 ◽  
Author(s):  
Kazuaki Inaba ◽  
Ibuki Mashio
Keyword(s):  
Thin Film ◽  
Water Flow ◽  
Damage Model ◽  
Interfacial Strength ◽  
Crystalline Lens ◽  
Element Analysis ◽  
Significant Difference ◽  
Energy Release Rates ◽  
Cohesive Damage ◽  
Good Agreement

Abstract To model the peeling phenomenon during cataract surgery and examine the effect of fluid flow during surgery, we constructed a simplified physical system and compared the case where only static pressure is applied to the adhesive thin film and the case where water flow is applied to the film by suction. From experiments with and without suctioning, the energy release rates of the adhesive thin film were calculated to be approximately 10 N/m, and no significant difference was confirmed with or without suction. We modeled the peeling phenomenon using the cohesive damage model and performed a finite element analysis considering the coupling of the fluid and membrane. The simulation results without suction were in good agreement with the theoretical values of the stress and deflection. When the water flow was applied to collide with the peeling part, the film deflection at the center became smaller, and the radial and circumferential stresses became smaller. From this result, it is shown that the stress acting on the membrane surrounding the crystalline lens can be reduced and peeling can be performed by successfully using the water flow for peeling.

scholarly journals Strength Prediction and Experimental Validation of Adhesive Joints Including Polyethylene, Carbon-Epoxy and Aluminium Adherends

2010 ◽  
Vol 636-637 ◽  
pp. 1157-1164 ◽  
Author(s):  
A.M.G. Pinto ◽  
A.G. Magalhães ◽  
Raul D.S.G. Campilho ◽  
Marcelo F.S.F. de Moura ◽  
A.P.M. Baptista
Keyword(s):  
Chromic Acid ◽  
Damage Model ◽  
Surface Preparation ◽  
Numerical Results ◽  
Reinforced Plastic ◽  
Special Surface ◽  
Carbon Fibre Reinforced Plastic ◽  
Inert Surfaces ◽  
Cohesive Damage ◽  
Good Agreement

Polyolefins are especially difficult to bond due to their non-polar, non-porous and chemically inert surfaces. Acrylic adhesives used in industry are particularly suited to bond these materials, including many grades of polypropylene (PP) and polyethylene (PE), without special surface preparation. In this work, the tensile strength of single-lap PE and mixed joints bonded with an acrylic adhesive was investigated. The mixed joints included PE with aluminium (AL) or carbon fibre reinforced plastic (CFRP) substrates. The PE substrates were only cleaned with isopropanol, which assured cohesive failures. For the PE CFRP joints, three different surfaces preparations were employed for the CFRP substrates: cleaning with acetone, abrasion with 100 grit sand paper and peel-ply finishing. In the PE AL joints, the AL bonding surfaces were prepared by the following methods: cleaning with acetone, abrasion with 180 and 320 grit sand papers, grit blasting and chemical etching with chromic acid. After abrasion of the CFRP and AL substrates, the surfaces were always cleaned with acetone. The tensile strengths were compared with numerical results from ABAQUS® and a mixed mode (I+II) cohesive damage model. A good agreement was found between the experimental and numerical results, except for the PE AL joints, since the AL surface treatments were not found to be effective.

Probabilistic Properties of Fatigue Damage and an Equivalent Damage Simplification Model for Multi-Level Load Spectra

2016 ◽  
Vol 08 (02) ◽  
pp. 1650017 ◽  
Author(s):  
X. R. Liu ◽  
Q. Sun
Keyword(s):  
Fatigue Damage ◽  
Damage Model ◽  
Fatigue Tests ◽  
Al Alloy ◽  
Test Results ◽  
Load Spectrum ◽  
Load Spectra ◽  
Multi Level ◽  
Load Sequence ◽  
Good Agreement

An equivalent fatigue damage simplification model for multi-level load spectrum is proposed. On the basis of the probabilistic fatigue damage model which takes load sequence effect into account and the constant amplitude fatigue tests, probabilistic properties of damage accumulated in one loading block are achieved quantitatively by statistical methods. The new simplification model can ensure that, for the original spectrum and simplified spectrum, the probabilistic properties of fatigue damage are almost the same. Fatigue tests for Al-alloy straight plates are performed to test the validity of the model. The test results are in good agreement with predicted results.

scholarly journals Multilevel Seismic Damage Behavior Correlation Analysis for RC Framed Structures

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Jianguang Yue
Keyword(s):  
Damage Model ◽  
Frame Structure ◽  
Structural Level ◽  
Test Results ◽  
Framed Structures ◽  
Material Stiffness ◽  
Rc Framed Structures ◽  
Structural Levels ◽  
Good Agreement ◽  
Section Level

Five structural levels, that is, material level, section level, member level, storey level, and structure level, were proposed to analyze the multilevel nonlinear mechanism of the reinforced concrete (RC) framed structures. Based on the presented deformation equivalent principle, a generalized stiffness damage model was developed for each structural level. At each structural level, the stiffness damage value can be calculated by the integration of the material stiffness damage. Furthermore, an impact factor was proposed to reflect the damage correlations between different structural levels. In order to verify this method, the proposed method was used to study the damage evolutions at various structural levels of a 12-storey frame structure. The numerical model utilizing the proposed analysis method produces results in good agreement with the test results of the 12-storey frame structure. It shows that the proposed method is useful to assess the structure multilevel damage performance and to design a new structure.

scholarly journals Spine Examination during COVID-19 Pandemic via Video Consultation

2021 ◽  
Author(s):  
Tom Jansen ◽  
Martin Gathen ◽  
Amadeo Touet ◽  
Hans Goost ◽  
Dieter Christian Wirtz ◽  
...  
Keyword(s):  
Pain Intensity ◽  
Range Of Motion ◽  
Test Results ◽  
Risk Of Infection ◽  
Face To Face ◽  
Reliable Tool ◽  
Provocation Tests ◽  
Active Range Of Motion ◽  
Video Consultation ◽  
Good Agreement

Abstract Introduction During the current COVID-19 pandemic video consultations are increasingly common in order to minimize the risk of infection for staff and patients. The aim of this study was to evaluate the feasibility of a spine examination via video. Methods A total of 43 patients were recruited. Each participant underwent a video-based (VB) and a conventional face-to-face (FTF) spine examination. Pain intensity, active range of motion, inspection, a neurophysiologic basic exam and provocations tests were evaluated using video-based and face-to-face methods. Results The intra-rater reliability (IRR) was measured between both examinations. Good to very good IRR values were obtained in inspection (Kappa between 0,752 und 0,944), active range of motion and basic neurophysiological examination (Kappa between 0,659 und 0,969). Only moderate matches were found in specific provocation tests (Kappa between 0,407 und 0,938). A video-based spine examination is a reliable tool for measuring pain intensity, active range of motion and a basic neurophysiologic exam. Conclusion A basic spine examination during a video consultation is possible. A good agreement of the test results between video-based and face-to-face examination could be found.

Design of combined brake system for light weight scooters

2021 ◽  
pp. 095440702110240
Author(s):  
Yuan-Ting Lin ◽  
Chyuan-Yow Tseng ◽  
Jao-Hwa Kuang ◽  
Yeong-Maw Hwang
Keyword(s):  
Ride Comfort ◽  
Brake System ◽  
Force Distribution ◽  
Test Results ◽  
Systematic Method ◽  
Braking Performance ◽  
Evaluation Indexes ◽  
Low Costs ◽  
Braking Force ◽  
Good Agreement

The combined brake system (CBS) is a mechanism that links the front and rear brakes for scooters. For two-wheeled scooters, a CBS with appropriate braking force distribution can reduce the risk of crashing accidents due to insufficient driving proficiency. The design of the braking force distribution for a CBS is challenging to the designer because it has to fulfill many requirements such as braking performance, ride comfort, reliability, and low costs. This paper proposes a systematic method to optimize the parameters of CBS. The evaluation indexes for the design are first discussed. The steps to determine the critical parameter to meet the indexes and a method to predict braking performance are developed. Finally, driving tests are carried out to verify the effectiveness of the proposed method. Experimental results showed that the deceleration of the tested scooter equipped with the designed CBS achieves an average mean fully developed deceleration (MFDD) of 5.246 m/s2, higher than the homologation requirement. Furthermore, the proposed method’s prediction of braking performance is in good agreement with the test results, with errors <1%.

Study on the stiffness degradation in concrete continuous beam with externally prestressed CFRP tendons under fatigue loading

2021 ◽  
pp. 136943322199249
Author(s):  
Xing Li ◽  
Jiwen Zhang ◽  
Jun Cheng
Keyword(s):  
Fatigue Life ◽  
Fatigue Loading ◽  
Load Level ◽  
Fiber Reinforced Polymer ◽  
Stiffness Degradation ◽  
Test Results ◽  
Reinforced Polymer ◽  
Continuous Beams ◽  
Practical Engineering ◽  
Good Agreement

This paper presents fatigue behaviors and the stiffness degradation law of concrete continuous beams with external prestressed carbon fiber-reinforced polymer (CFRP) tendons. Three specimens were tested under fatigue loading, and the influence of different load levels on the stiffness degradation and fatigue life were studied, and it was found that the stiffness degradation of three test specimens exhibited a three-stage change rule, namely rapid decrease, stable degradation, and sharp decline, but there are obvious differences in the rate and amplitude of stiffness degradation. The load level has a significant influence on the fatigue life of the test specimens. An analytical model with load level considered was proposed to calculate the residual stiffness and predict the stiffness degradation, which is in good agreement with the test results. The model of stiffness degradation presents a possible solution for practical engineering applications of concrete continuous beams with externally prestressed CFRP tendons subjected to different fatigue loadings.

Investigating the vibrational behaviour of a rotating two-blade propeller by using a self-tracking method

2018 ◽  
Vol 233 (3) ◽  
pp. 835-847 ◽  
Author(s):  
Mohammad-Reza Ashory ◽  
Farhad Talebi ◽  
Heydar R Ghadikolaei ◽  
Morad Karimpour
Keyword(s):  
Natural Frequency ◽  
Measurement Errors ◽  
Mode Shapes ◽  
Model Parameters ◽  
Test Results ◽  
Modal Assurance Criterion ◽  
Tracking Method ◽  
Strong Resemblance ◽  
Test Scenarios ◽  
Good Agreement

This study investigated the vibrational behaviour of a rotating two-blade propeller at different rotational speeds by using self-tracking laser Doppler vibrometry. Given that a self-tracking method necessitates the accurate adjustment of test setups to reduce measurement errors, a test table with sufficient rigidity was designed and built to enable the adjustment and repair of test components. The results of the self-tracking test on the rotating propeller indicated an increase in natural frequency and a decrease in the amplitude of normalized mode shapes as rotational speed increases. To assess the test results, a numerical model created in ABAQUS was used. The model parameters were tuned in such a way that the natural frequency and associated mode shapes were in good agreement with those derived using a hammer test on a stationary propeller. The mode shapes obtained from the hammer test and the numerical (ABAQUS) modelling were compared using the modal assurance criterion. The examination indicated a strong resemblance between the hammer test results and the numerical findings. Hence, the model can be employed to determine the other mechanical properties of two-blade propellers in test scenarios.

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