Author
Pericles S. Theocaris
Bio: Pericles S. Theocaris is an academic researcher from National Technical University of Athens. The author has contributed to research in topics: Stress intensity factor & Fracture mechanics. The author has an hindex of 27, co-authored 191 publications receiving 2774 citations.
Papers published on a yearly basis
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TL;DR: In this paper, the Mises elastic-plastic boundary is introduced to define the core region, instead of the respective circle, and the minimum value of the strain-energy density is replaced by the minimum values of the radius of the elastic boundary in the role of the decisive quantity defining the direction of crack propagation.
159 citations
145 citations
Book•
05 Oct 1987
TL;DR: In this paper, the influence of the mesophase on the thermal behavior of composites is discussed. But the authors do not consider the effects of mesophases on the physical properties of composite materials.
Abstract: Models for composite materials.- retardation spectra of composites indicating the existence of a mesophase.- static and dynamic properties of composites as influenced by the mesophase.- the influence of the mesophase on the thermal behaviour of composites.- the glass transition of composites and influence of the mesophase.- mechanisms of moisture absorption in composites.- shrinkage stress at the mesophase developed during casting.- stress singularities at the mesophase due to the geometry of inclusions.- stress singularities in cracked phases.
111 citations
TL;DR: In this article, the T -criterion was applied in the case of the fracture of a ductile material and the predicted and measured quantities are in good agreement, especially in cases where existing other fracture criteria fail.
74 citations
TL;DR: In this article, an exhaustive theoretical analysis of the distribution of t v -component around the tip of crack under in-plane modes of loading was undertaken, and it was found that the T v -distribution along the Mises initial elastic-plastic boundary presents always a maximum in front of the crack tip, whose position and magnitude depend on the biaxiality factor k and the angle of loading β.
71 citations
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1,969 citations
TL;DR: In this paper, a new technique for the finite element modeling of cracks with multiple branches, multiple holes and cracks emanating from holes is presented, which allows the representation of crack discontinuities and voids independently of the mesh.
Abstract: SUMMARY Extensions of a new technique for the nite element modelling of cracks with multiple branches, multiple holes and cracks emanating from holes are presented. This extended nite element method (X-FEM) allows the representation of crack discontinuities and voids independently of the mesh. A standard displacementbased approximation is enriched by incorporating discontinuous elds through a partition of unity method. A methodology that constructs the enriched approximation based on the interaction of the discontinuous geometric features with the mesh is developed. Computation of the stress intensity factors (SIF) in dierent examples involving branched and intersecting cracks as well as cracks emanating from holes are presented to demonstrate the accuracy and the robustness of the proposed technique. Copyright ? 2000 John Wiley & Sons, Ltd.
943 citations
922 citations
TL;DR: In this paper, a high speed video system was used, which allowed us to precisely observe the cracking mechanisms and identified nine crack coalescence categories with different crack types and trajectories.
Abstract: Cracking and coalescence behavior has been studied experimentally with prismatic laboratory-molded gypsum and Carrara marble specimens containing two parallel pre-existing open flaws. This was done at both the macroscopic and the microscopic scales, and the results are presented in two separate papers. This paper (the first of two) summarizes the macroscopic experimental results and investigates the influence of the different flaw geometries and material, on the cracking processes. In the companion paper (also in this issue), most of the macroscopic deformation and cracking processes shown in this present paper will be related to the underlying microscopic changes. In the present study, a high speed video system was used, which allowed us to precisely observe the cracking mechanisms. Nine crack coalescence categories with different crack types and trajectories were identified. The flaw inclination angle (β), the ligament length (L), that is, intact rock length between the flaws, and the bridging angle (α), that is, the inclination of a line linking up the inner flaw tips, between two flaws, had different effects on the coalescence patterns. One of the pronounced differences observed between marble and gypsum during the compression loading test was the development of macroscopic white patches prior to the initiation of macroscopic cracks in marble, but not in gypsum. Comparing the cracking and coalescence behaviors in the two tested materials, tensile cracking generally occurred more often in marble than in gypsum for the same flaw pair geometries.
568 citations
TL;DR: In this article, the authors discuss how solvent evaporation, thermal effects, and the resulting stresses at the polymer-dispersed phase interface cause a complex, but at least partially understood array of effects ranging from void formation to stress-dilated regions or even zones of compression in the polymer layers nearest the polymers interface.
558 citations