Fracture characteristics of wood under mode I, mode II and mode III loading

2002 ◽  
Vol 82 (17-18) ◽  
pp. 3289-3298 ◽  
Author(s):  
Klaus Frühmann ◽  
Alexander Reiterer ◽  
Elmar K. Tschegg ◽  
Stefanie S. Stanzl-Tschegg
Keyword(s):  
Mode I ◽  
Mode Ii ◽  
Mode Iii ◽  
Fracture Characteristics

Fracture characteristics of wood under mode I, mode II and mode III loading

2002 ◽  
Vol 82 (17-18) ◽  
pp. 3289-3298 ◽  
Author(s):  
Klaus Frühmann ◽  
Alexander Reiterer ◽  
Elmar K. Tschegg ◽  
Stefanie S. Stanzl-tschegg
Keyword(s):  
Mode I ◽  
Mode Ii ◽  
Mode Iii ◽  
Fracture Characteristics

Buckling Evolution of Microelectromechanical Structures

1998 ◽  
Vol 518 ◽  
Author(s):  
Xin Zhang ◽  
Tong-Yi Zhang ◽  
Yitshak Zohar
Keyword(s):  
Theoretical Analysis ◽  
Local Buckling ◽  
Experimental Results ◽  
Mode I ◽  
Mode Ii ◽  
Mode Iii ◽  
Sacrificial Layers

AbstractThis study reports in-situ observations of the buckling evolution of microelectromechanical structures during etching of their underneath sacrificial layers. As the etching went on, the buckling pattern evolved from mode I, the sinusoidal half-waves, to mode II, the constrained sinusoidal half-waves, to mode III, the conventional mode, and finally to mode IV, the blister- like local buckling. Closed formulae were derived from theoretical analysis, and the experimental results agreed well with the theoretical ones.

Stress Intensity Factors for Cracks Emanating from a Notch under Shear-Mode Loading

2018 ◽  
Vol 774 ◽  
pp. 48-53
Author(s):  
Jana Horníková ◽  
Pavel Šandera ◽  
Stanislav Žák ◽  
Jaroslav Pokluda
Keyword(s):  
Stress Intensity ◽  
Critical Length ◽  
Shear Mode ◽  
Mode I ◽  
Mode Ii ◽  
Mode Iii ◽  
Loading Mode ◽  
Notch Stress ◽  
Notch Geometry ◽  
Mode Ii Loading

The influence of the notch geometry on the stress intensity factor at the front of the emanating cracks is well known for the opening loading mode. The critical length of the crack corresponding to a vanishing of the influence of the notch stress concentration can be approximately expressed by the formula aI,c = 0.5ρ(d/ρ)1/3, where d and ρ are the depth and radius of the notch, respectively. The aim of the paper was to find out if this formula could be, at least nearly, applicable also to the case of shear mode loading. The related numerical calculations for mode II and III loading were performed using the ANSYS code for various combinations of notch depths and crack lengths in a cylindrical specimen with a circumferential U-notch. The results revealed that, for mode II loading, the critical length was much higher than that predicted by the formula for mode I loading. On the other hand, the critical lengths for mode I and mode III were found to be nearly equal.

Three-Dimensional Mode Separation to Obtain Stress Intensity Factors

2006 ◽  
Author(s):  
Pei Gu ◽  
R. J. Asaro
Keyword(s):  
Stress Intensity ◽  
Crack Propagation ◽  
Stress Intensity Factors ◽  
Three Dimensional ◽  
Integral Approach ◽  
Mode I ◽  
Mode Ii ◽  
Intensity Factors ◽  
Mode Iii ◽  
Mode Separation

For mixed-mode loading at a crack tip under small-scale yielding condition, mode I, mode II and mode III stress intensity factors control the crack propagation. This paper discusses three-dimensional mode separation to obtain the three stress intensity factors using the interaction integral approach. The 2D interaction integral approach to obtain mode I and mode II stress intensity factors is derived to 3D arbitrary crack configuration for mode I, mode II and mode III stress intensity factors. The method is implemented in a finite element code using domain integral method and numerical examples show good convergence for the domains around the crack tip. A complete solution for the three stress intensity factors is obtained for a bar with inclined crack face to the cross-section from numerical calculations. The solution for the bar is plotted into curves in terms of a set of non-dimensional parameters for practical engineering purpose. From the solution, mode mixity along the crack front and its implication to the direction of crack propagation is discussed.

Fractographic Observation of Various Loading Modes of Fibre Reinforced Laminates

2012 ◽  
Vol 730-732 ◽  
pp. 337-342 ◽  
Author(s):  
Rosa Marat-Mendes ◽  
Manuel de Freitas
Keyword(s):  
Mixed Mode ◽  
Mode I ◽  
Mode Ii ◽  
Scanning Electron Micrographs ◽  
Mode Iii ◽  
Fibre Breakage ◽  
Pull Out ◽  
Fractographic Features ◽  
Static Conditions ◽  
Scanning Electron

One of the major disadvantages of laminated composites is their tendency to delaminate. Unidirectional glass/epoxy laminates have been tested under static conditions by the use of fracture mechanics. Mode I, mode II, mixed mode I-II, mode III and mixed mode II-III tests were performed. Double cantilever beam (DCB), end-notched flexure (ENF), mixed-mode bending (MMB) and edge crack torsion (ECT) specimens were used. Scanning electron microscopy technique was used to identify distinguishing fractographic features and to establish the differences between the various modes of fracture after specimens testing. The propagated orientation of the delamination could be specified from the patterns of fracture surface. Scanning electron micrographs of fractured surfaces showed that the most predominant fractographic features in mode I and mode II are the large amount of fibre pull-out and the cusps markings respectively. In the MMB specimen the fracture surfaces are characterized by fibre breakage under shearing with fractures localized in the resin with cusps having an orientation of 90º (mode II) and also fractures localized in the resin and along the resin/fibre interface (mode I). Mode III characterization concluded that some limited mixed mode II-III seems to be present for ECT specimen on delamination initiation and growth, but a large majority of mode III delamination is present.

Dynamic Analysis of Non-Symmetric Cracks Extension

2000 ◽  
Vol 16 (3) ◽  
pp. 157-167
Author(s):  
Yen-Ling Chung ◽  
Mei-Rong Chen
Keyword(s):  
Crack Tip ◽  
Mode I ◽  
Mode Ii ◽  
Mode Iii ◽  
Dynamic Stress Intensity Factors ◽  
Surface Displacements ◽  
Crack Tips ◽  
Self Similar ◽  
Rayleigh Wave Speed ◽  
Complete Solutions

ABSTRACTThis paper applies the method of self-similar potentials to analyze the dynamic behaviors of the problems of mode-I, mode-II, and mode-III cracks propagating along the x-axis with constant speed, while the constant speeds of both crack tips are not the same, called nonsymmetric crack expansion. It is assumed that an unbound homogeneous isotropic elastic material is at rest for time t < 0. However, for time t ≥ 0, a central crack starts to extend from zero length along the x-axis. On the crack surfaces of x ≥ 0, there exists uniform distributed load such that the rightmost crack tip propagates with speed ms, while the leftmost crack tip with speed s, where m > 1 and is constant. First, the complete solutions of the mode-I, mode-II, and mode-III problems are obtained. After the complete solutions are found, attention is focused on the crack surface displacements and dynamic stress intensity factors. The results of this study show that the DSIF is equal to the static SIF when the crack-tip speed is zero, and DSIF is zero as the crack-tip speed approaches the Rayleigh-wave speed. Moreover, for the special case m = 1 which indicates that the velocities of both crack tips are the same, the DSIFs of this three modes in this study is the same as those of Ref. [15].

Effect of Cold-Induced on Quality of Black Carp Fillet Stored at Controlled Freezing-Point

2014 ◽  
Vol 941-944 ◽  
pp. 1045-1050 ◽  
Author(s):  
Lei Zou ◽  
Jin Qing Wan ◽  
Yao Guang Zhong ◽  
Jia Li ◽  
Yan Feng Zhao
Keyword(s):  
Cathepsin B ◽  
Free Amino ◽  
Ph Value ◽  
Freezing Point ◽  
Mode I ◽  
Mode Ii ◽  
Mode Iii ◽  
Black Carp ◽  
Controlled Freezing

Taken black carp fillet as the experimental material, effects of cold-induced on the quality of black carp fillets were studied. Three kinds of cold-induced modes were conducted in this experiment: 10°C constant temperature induction ( mode I ); 2°C/2h ( mode II ); 1°C/1h ( mode III ), at the same time did a comparison with controlled freezing-point storage ( mode IV ). The effect of cold-induced on pH, liquid loss, K value, activity of cathepsin B, free amino acid and proteolysis were compared. Results showed that: the pH value in fillets declined mildly at the storage, the drip loss value and K-value of fillets increased gradually as storage time increased. The K-value of fillets stored at mode I and II increased sharply, while relatively little change was observed in mode III and IV. Cathepsin B activities increased little bit at the storage. The cathepsin B activities of mode III was highest at 11.302U•g-1, when fillets were stored at controlled freezing-point (44h). Mode II was the second at 10.522 U•g-1. The total free amino acids (FAAs) of all modes increased to some extent. At 44 hours, the increment of total FAAs in mode II and III were 20.19% and 19.49%, which were superior to mode I (12.27%) and IV (12.97%). No significant differences in protein degradation were observed among those cold-induced modes, but it showed proteolysis on the SDS-PAGE.

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