Seminaria Mechaniki Materiałów

Pawińskiego 5b

kolor czcionki + kolor tła = plan do 7 dni.

2018-05-23 14:00, Sala: Aula im. Wacława Olszaka, piętro II
Prof. Julien Bourgeois
Univ. Bourgogne-Franche-Comté, Institut FEMTO-ST, CNRS, France

Realizing programmable matter with modular robots

2018-04-25 14:00, Sala: Aula im. Wacława Olszaka, piętro II
dr hab. inż. Stanisław Kucharski

Efekt skali obserwowany w testach indentacji monokryształu miedzi

2018-04-18 14:00, Sala: Aula im. Wacława Olszaka, piętro II
Prof. Sebastien Mercier
Université de Lorraine, France

Behavior of porous material under dynamic conditions

The fracture of ductile materials is often the result of the nucleation, growth and coalescence of microscopic voids. In the present talk, we mainly focus on the growth process of voids. In dynamic loading, micro-voids sustain an extremely rapid expansion which generates strong acceleration of particles in the vicinity of cavities. These micro-inertia effects are thought to play an important role in the development of dynamic damage. To account for these large acceleration in the constitutive behavior, a multi-scale approach has been proposed in LEM3[1] and it has been shown that the micro inertia contribution to the macro stress is significant when dynamic loading is considered. The presentation will exemplify micro-inertia effects by analyzing spall test in tantalum [2,3], crack propagation in dynamic loading [4]. In these two examples, an intrinsic length scale representative of the microstructure (size of the voids) is controlling the macroscopic response. This lengthscale was also shown to play an important role in the shock wave propagation. Indeed Czarnota et al [7] have been able to determine the width of the shock front which is scaled by the lengthscale. Finally, the model was extended to account for non spherical shape of voids [5,6]. The talk will present some flow surfaces for spheroidal voids. Under specific loading, non conventional flow surfaces are obtained. This result has been confirmed by finite element calculations and can be explained by the strong contribution of inertia. References [1] Molinari A., Mercier S., (2001), Micromechanical modelling of porous materials under dynamic loading, Journal of the Mechanics and Physics of Solids 49, 1497-1516, 2001 [2] Roy, G., (2003). Vers une modélisation approfondie de l’endommagement ductile dynamique. Investigation expérimentale d’une nuance de tantale et développements théoriques. Doctorat, Ecole Nationale Supérieure de Mécanique et d’Aéronautique, Université de Poitiers, France. [3]C. Czarnota , N. Jacques, S. Mercier, A. Molinari , (2008). Modelling of dynamic ductile fracture and application to the simulation of plate impact tests on tantalum, J. Mech. Phys. Solids 56(4):1624-1650. [4] Jacques, N; Mercier, S; Molinari, A, (2012) Effects of microscale inertia on dynamic ductile crack growth, J. Mech. Phys. Solids, 60(4): 665- 690 [5] Sartori C., Mercier S., Jacques N., Molinari A. (2015), Constitutive behavior of porous ductile materials accounting for micro-inertia and void shape, Mechanics of Materials, 80, Part B, 324-339. [6] Sartori C., Mercier S., Jacques N., Molinari A. (2016), On the dynamic behavior of porous ductile solids containing spheroidal voids, Int. J. Solids Struct., 97-98,150-167. [7] Czarnota C., Molinari A., Mercier S. (2017), The structure of steady shock waves in porous metals, J. Mech. Phys. Solids, 107, p. 204-228
2018-02-28 14:00, Sala: Aula im. Wacława Olszaka, piętro II
dr inż. Dariusz Jarząbek

Wpływ połączenia metal-ceramika na właściwości mechaniczne elektroosadzanych kompozytów Ni-SiC

2018-02-21 14:00, Sala: Aula im. Wacława Olszaka, piętro II
mgr inż. Sandra Musiał

Badania pękania stali P110 z wykorzystaniem korelacji obrazów cyfrowych

2018-02-14 14:00, Sala: Aula im. Wacława Olszaka, piętro II
mgr inż. Justyna Maj

Wpływ mikrostruktury na właściwości mechaniczne, termiczne i tribologiczne infiltrowanych kompozytów gradientowych Al2O3-AlSi12

2018-02-07 14:00, Sala: Aula im. Wacława Olszaka, piętro II
dr Karel Tuma
Charles University, Czech Republic

Finite element simulation of deformation of a bovine eye

2017-12-13 14:00, Sala: Aula im. Wacława Olszaka, piętro II
dr inż. Marcin Nowak

Procedura wyznaczania trójwymiarowego pola przemieszczeń z użyciem korelacji obrazów cyfrowych

2017-11-22 14:00, Sala: Aula im. Wacława Olszaka, piętro II
dr inż. Przemysław Sadowski

Doświadczalne badanie wpływu konfiguracji i chropowatości na tarcie przy przejściu od smarowania elastohydrodynamicznego do mieszanego

2017-11-15 14:00, Sala: Aula im. Wacława Olszaka, piętro II
dr hab. Urszula Zajączkowska
SGGW

Wybrane problemy fizyki roślin

2017-10-25 14:00, Sala: Aula im. Wacława Olszaka, piętro II
Prof. Joze Korelc
University of Ljubljana, Slovenia

Higher order sensitivity analysis in formulation of computational models

2017-10-11 14:00, Sala: Aula im. Wacława Olszaka, piętro II
mgr inż. Kamil Bochenek

Wpływ dodatku renu i tlenku glinu na właściwości mechaniczne i odporność na utlenianie związków międzymetalicznych na bazie NiAl wytwarzanych metodą metalurgii proszków

2017-06-28 14:00, Sala: Aula im. Wacława Olszaka, piętro II
mgr inż. Justyna Jakubowska

Wpływ mikrostruktury na właściwości mechaniczne, termiczne i tribologiczne infiltrowanych kompozytów gradientowych Al2O3-Al

2017-06-21 14:00, Sala: Aula im. Wacława Olszaka, piętro II
mgr inż. Michał Majewski

Reprezentacja cech morfologicznych mikrostruktury w mikromechanicznych modelach materiałów kompozytowych

2017-06-08 11:00, Sala: Aula im. Wacława Olszaka, piętro II
Prof. Igor Sevostianov
New Mexico State University, USA

Cross-property connections for heterogeneous materials and their applications

Cross-property connections for heterogeneous materials belong to the realm of fundamental problems of engineering science and physics. They relate changes in different physical properties caused by various inhomogeneities (cracks, pores, inclusions), or, more generally – by the presence of certain microstructure. Their practical usefulness lies in the fact that one physical property (say, electrical conductivity) may be easier to measure than the other (say anisotropic elastic constants). This allows one to bypass difficulties of expressing the elastic properties in terms of relevant microstructural information (that, in addition, may not be available). Such connections are also helpful in the design of microstructures for the combined conductive/mechanical performance and in monitoring of accumulated damage. In the presentation, connections between conductivities and elastic compliances are discussed and specified for several materials: YSZ plasma sprayed coatings, short fiber reinforced thermoplastics, aluminum foam, swelled austenitic steel. The possibility to use cross-property connections in the context of the evaluation of strength loss due to the cracks formation is also addressed. The approach is illustrated by the developed quantitative crack detector scanner that evaluates strength reduction from electrical conductivity measurements.
2017-06-08 12:00, Sala: Aula im. Wacława Olszaka, piętro II
Prof. Gennady Mishuris
Aberystwyth University, UK

Energy release rate in hydraulic fracture: Can we neglect an impact of the hydraulically induced shear stress?

We discuss a novel model of hydraulic fracture (HF) formulation which accounts for the hydraulically induced shear stress at the crack faces. It utilizes a general form of the elasticity operator alongside a revised fracture propagation condition based on the critical value of the energy release rate. We show that the revised formulation is always in agreement with the linear elastic fracture mechanics. Furthermore, our numerical simulations have highlighted advantages of the revised HF model in comparison with those which fail to account for the shear stress. In particular, we found that the small toughness regime no longer presents a significant computational challenge. The modified formulation opens new ways to analyse the physical phenomenon of HF, as well as improving the reliability and efficiency of its numerical simulation.


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