Publications de Ebrahim Farmand Ashtiani

Effects of large scale bridging in load controlled fatigue delamination of unidirectional carbon-epoxy specimens

John Botsis, Joël Cugnoni, Ebrahim Farmand Ashtiani

Fatigue delamination growth in composites is accompanied by large scale bridging (LSB) that yields important toughening effects. However, the extent of this mechanism depends on the laminate geometry rendering its modeling a challenging task. This work pre ...

Elsevier2016

Studies on large scale bridging in delamination of unidirectional and cross-ply laminates

Ebrahim Farmand Ashtiani

Delamination propagation in fibrous laminates is often accompanied by development of a damage zone, within which intact fibers bridge the crack faces that constitutes a major toughening mechanism. A direct experimental assessment of the crack closure tract ...

EPFL2016

Specimen thickness dependence of large scale fiber bridging in mode I interlaminar fracture of carbon epoxy composite

John Botsis, Joël Cugnoni, Ebrahim Farmand Ashtiani

Large scale bridging is an important toughening mechanism in composite laminates that depends on the specimen geometry as well as the constituent materials. In this work, an iterative approach is applied to identify the effect of specimen thickness on trac ...

Elsevier2015

Delamination in cross-ply laminates: Identification of traction-separation relations and cohesive zone modeling

John Botsis, Joël Cugnoni, Ebrahim Farmand Ashtiani, David Enrique Alanis Rojas

Identification of traction separation relations is at the forefront of damage and fracture mechanics of composite laminates. Such relations are of particular interest in fracture of laminates consisting of layers of different fiber orientations. In this st ...

Elsevier2015

An iterative analytical/experimental study of bridging in delamination of the double cantilever beam specimen

Anastasios Vassilopoulos, John Botsis, Behzad Dehghan Manshadi, Ebrahim Farmand Ashtiani

Large scale bridging in mode-I delamination of layered composites is an important toughening mechanism. While its extent depends on constituent materials, it is also influenced by specimen geometry. Here, an analytical approach is adopted to express the th ...

Elsevier2014

Monitoring and characterization of the interfacial fracture in sandwich composites with embedded multiplexed optical sensors

John Botsis, Joël Cugnoni, Ebrahim Farmand Ashtiani

Interfacial debonding is one of the most critical damage modes that threatens the structural performance of sandwich composites. In this work, integrated multiplexed fiber Bragg grating (FBG) sensors of 1 mm gauge length are used for detection and characte ...

Elsevier Sci Ltd2013