From Macro to Meso and Nano Material Failure. Quantized Cohesive Model for Fractal Cracks

Author(s):  
Michael P. Wnuk*
2009 ◽  
Vol 76 (4) ◽  
pp. 548-559 ◽  
Author(s):  
Michael P. Wnuk ◽  
Arash Yavari

Polymers ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 492
Author(s):  
Zhen Pei Chow ◽  
Zaini Ahmad ◽  
King Jye Wong ◽  
Seyed Saeid Rahimian Koloor ◽  
Michal Petrů

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.


2020 ◽  
pp. 109438
Author(s):  
Scott Sneddon ◽  
Yang Xu ◽  
Mark Dixon ◽  
David Rugg ◽  
Peifeng Li ◽  
...  

2019 ◽  
Vol 18 (1) ◽  
pp. 14-16
Author(s):  
Diego Veiga Bezerra ◽  
Luis Eduardo Munhoz da Rocha ◽  
Dulce Helena Grimm ◽  
Carlos Abreu de Aguiar ◽  
Luiz Müller Ávila ◽  
...  

ABSTRACT Objective: To evaluate the healing of the modified inverted “Y” incision in patients with scoliosis due to myelomeningocele. Methods: Retrospective study through medical records review of patients with myelomeningocele surgically treated with a modified inverted “Y” approach between January 2013 and December 2015. Results: We analyzed the medical records of six patients. Two patients progressed with skin complications in the immediate postoperative period and only one of them required surgical intervention for debridement and suturing. In another patient, it was necessary to perform two surgical reviews due to material failure without skin complications in these interventions. Conclusions: The modified inverted “Y” technique is a great alternative to traditional incision and inverted “Y” because it has good results in patients with spina bifida associated with poor skin conditions treated surgically for correction of spinal deformities. Level of Evidence IV; Case series.


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