scholarly journals Maximum tangential stress coupled with probabilistic aspect of fracture toughness of hybrid bio-composite

2018 ◽  
Vol 21 (2) ◽  
pp. 201-214 ◽  
Author(s):  
Prakash Chandra Gope
Keyword(s):  
Fracture Toughness ◽  
Tangential Stress ◽  
Maximum Tangential Stress

Evaluation of size effect on mixed-mode fracture behavior of epoxy/silica nanocomposites

2017 ◽  
Vol 52 (4) ◽  
pp. 239-248 ◽  
Author(s):  
Ahmad Ghasemi-Ghalebahman ◽  
Javad Akbardoost ◽  
Yaser Ghaffari
Keyword(s):  
Fracture Toughness ◽  
Tangential Stress ◽  
Mixed Mode ◽  
Fracture Behavior ◽  
Process Zone ◽  
Maximum Tangential Stress ◽  
Mixed Mode Fracture ◽  
Mode Fracture ◽  
Stress Criterion ◽  
Maximum Tangential Stress Criterion

The aim of this study was to examine the effect of size on the mixed-mode fracture toughness of quasi-brittle nanocomposites with the help of modified maximum tangential stress criterion. The literature reveals that the effect of size on mixed-mode fracture behavior of brittle nanocomposites has not been well investigated previously using modified maximum tangential stress criterion. The studied nanocomposites were made of epoxy resin reinforced with 7 wt%, 20–30 nm nanosilica. The accuracy of the method was assessed by taking into account the high-order terms of Williams series expansion along with finite element over-deterministic method. To investigate the effect of size on fracture toughness, a number of three-point semi-circular bending tests with different radii and four angles of edge–crack orientation were conducted and subjected to mixed-mode loading. The size of fracture process zone and apparent fracture toughness ( Kc) were also evaluated as a function of sample size. Experimental results showed that the proposed approach can accurately predict the fracture behavior of studied nanocomposites.

scholarly journals Research on the Size Effect of Unstable Fracture Toughness by the Modified Maximum Tangential Stress (MMTS) Criterion

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Jian Li ◽  
Zhao-Wen Du ◽  
Zhong-Ping Guo ◽  
De-Chun Ai
Keyword(s):  
Fracture Toughness ◽  
Size Effect ◽  
Tangential Stress ◽  
Maximum Tangential Stress ◽  
Unstable Fracture ◽  
Bending Tests ◽  
Three Point Bending ◽  
Higher Order Terms ◽  
Minimum Height ◽  
Significant Size

This paper investigates the unstable fracture toughness of specimens of different heights using the double-K model for three-point bending tests on notched concrete beams. It is shown that unstable fracture toughness exhibits a significant size effect. The modified maximum tangential stress (MMTS) criterion is used to explain the size effect of unstable fracture toughness. The MMTS criterion considers the higher order terms of the Williams series expansion of the stress field. The results show that the MMTS criterion can reasonably estimate unstable fracture toughness. It is recommended that the minimum height of the specimen be 200 mm when three-point bending tests on notched beams are used to determine unstable fracture toughness.

A Comparison of the Fracture Behaviour of Various Concrete Grades under Mixed Mode I/II Loading

2019 ◽  
Vol 827 ◽  
pp. 228-233
Author(s):  
Petr Miarka ◽  
Robin Janssen ◽  
Stanislav Seitl ◽  
Wouter de Corte
Keyword(s):  
Tangential Stress ◽  
High Strength Concrete ◽  
Fracture Resistance ◽  
Mixed Mode ◽  
Fracture Behaviour ◽  
High Strength ◽  
Critical Distance ◽  
Maximum Tangential Stress ◽  
Mode I ◽  
C 50

The Brazilian disc test with central notch is widely used to evaluate mixed mode I/II fracture resistance of brittle materials such as rocks and concrete. An analytical evaluation is used based on the maximum tangential stress (MTS) criterion and the generalised maximum tangential stress (GMTS) criterion. In this contribution two concrete types, a C 50/60 and a high strength concrete, were compared using the GMTS criterion. Also, the influence of critical distance rC on the fracture resistance under the mixed mode I/II was studied.

Investigation on the Stress Behaviour of Coating-Substrate Interface under Contact Loading

2013 ◽  
Vol 465-466 ◽  
pp. 1319-1323
Author(s):  
M. Zulfadli Mohamad Rani ◽  
A. L. Mohd Tobi ◽  
A.E. Ismail ◽  
W.A. Siswanto ◽  
A.A. Saad
Keyword(s):  
Tangential Stress ◽  
Coating Thickness ◽  
Maximum Tangential Stress ◽  
Fe Modelling ◽  
Substrate Interface ◽  
Fracture Failure ◽  
Simple Geometry ◽  
Elastic Mismatch ◽  
Stress Behaviour ◽  
Coating Fracture

This study is intended to predict the stress behavior of thick hard coating at the interface with the changes of coating stiffness and thickness to the substrate of Ti-6Al-4V and SCMV. The elastic mismatch between the coating and the substrate is presented in the value of Dundurs parameter α. The prediction is done using simple geometry of a cylinder-on-flat model in 2D analysis subjected to normal and tangential loading. Tangential stress distribution along the coating-substrate interface is then obtained from the FE modelling after a finite sliding of the cylinder. It is predicted that the maximum tangential stress value predicted at the interface which relates to coating fracture failure is increasing as stiffer coating is used on compliant substrate (i.e. increasing α values). The location of the maximum tangential stress predicted also changes from the trailing edge to the center of contact with increasing α values. Effect of changes of coating thickness on the predicted maximum tangential stress value is more significant for high positive α values. Risk of coating fracture at the interface is therefore predicted to increase with the increase of coating thickness and stiffness.

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