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Damage and fracture mechanics

Keywords: stress intensity factors, piezoelectric materials, quasi-brittle materials, fracture testing, debonding, effective stress-strain, SHM, fatigue damage, Smart Stress-Memory Patch Sensor
Fig. 1. Fracture test of concrete. Load per unit width vs crack opening displacement (COD) (Carloni).
Damage and fracture mechanics - Fig. 2
Fig. 2. FEM analysis of damage in three-point bending (Ferretti).
Fig. 3. The CM compared to the differential formulation (Ferretti).

Fracture Mechanics deals with the study of initiation and propagation of cracks in structural members through the investigation of the stress field around the crack tip and the energy dissipated as the crack propagates. Members of the research group carry out numerical, analytical, and experimental work with emphasis on:

  1. Ad-hoc formulations of stress intensity factor in linear elastic and piezoelectric media
  2. Investigation on the behaviour of cracked beams within the stability framework.
  3. Experimental and numerical behaviour of crack propagation in concrete, clay brick, Plexiglas, geopolymer, hydraulic mortar, and other quasi-brittle materials.
  4. Experimental, analytical, and numerical bond behaviour of composites applied to concrete and masonry.

In Damage Mechanics an internal variable is included in the constitutive law to represent the evolution of microstructural damage. Damage degradation can manifest itself in progressive material softening, for which reason numerical results based upon classical continuum mechanics are characterised by a pathological mesh dependence: to avoid this regularised continuum models have been introduced. Among these, there are the strain gradient models. A discontinuous Galerkin method has been developed. An alternative approach shows that nonlocal constitutive laws between stresses and strains are not strictly needed to construct a material model. Also the effective law, which is a local constitutive law, is suitable for modelling nonlocal effects if used with a formulation which is itself nonlocal, such as the Cell Method (CM).

A new fatigue sensor called Smart Stress- Memory Patch, which can estimate the cyclic number, the stress amplitude and the maximum stress from the measurement of crack length and acoustic emission (AE), is proposed for Structural Health Monitoring (SHM), to evaluate the fatigue damage of such infrastructure as bridges and ships.

Main publications

Carloni C. and Focacci F. (2016). FRP-Masonry Interfacial Debonding: An Energy Balance Approach to Determine the Influence of the Mortar Joints. European Journal of Mechanics A/Solids 55, 122–133.

D’Antino T., Carloni C., Sneed L.H., and Pellegrino C. (2015). Fatigue and Post-fatigue Behavior of PBO FRCM-Concrete Joints. International Journal of Fatigue 81, 91-104

Carloni C., D'Antino T., Sneed L.H., and Pellegrino C. (2015). Role of the Matrix Layers in the Stress-Transfer Mechanism of FRCM Composites Bonded to a Concrete Substrate. ASCE Journal of Engineering Mechanics 141, No. 6, 10.1061/(ASCE)EM.1943-7889.0000883.

Carloni C. and Subramaniam K.V. (2012) Application of Fracture Mechanics to Debonding of FRP from RC Members. ACI Special Publication 286, 1-10.

Nobile L., Gentilini, C. (2011). On the evaluation of the energy release rate in edge cracked beams. Recent Patents on Mechanical Engineering 4, No. 3, 220-225.

Boldrini C., Viola E. (2008). Crack energy density of a piezoelectric material under general electromechanical loading. Theoretical and Applied Fracture Mechanics 49, No. 3, 321-333.

Viola E., Boldrini C., Tornabene F. (2008). Nonsingular term effect on the fracture quantities of a crack in a piezoelectric medium. Engineering Fracture Mechanics 75, No. 15, 4542-4567.

Carloni C., Subramaniam K.V., and Metrovich B. (2008). Approccio Alternativo per la Determinazione degli Intensificatori degli Sforzi in Travi Fessurate (In Italian). In Proceedings of XXXVII Conference of the Italian Association of Experimental Analysis (AIAS ‘08). Rome (Italy), September 10-13, 2008.

Carloni C., Nobile L., Gentilini C. (2007). Stability of multi-cracked beams. AES Technical Reviews, Part B: International Journal of Advances in Mechanics and Applications of Industrial Materials 1, 69-78.

Piva A., Tornabene F., Viola E. (2007). Subsonic Griffith crack propagation in piezoelectric media. European Journal of Mechanics - A/Solids 26, No. 3, 440-457.

Subramaniam K.V., Carloni C., Nobile L. (2007). Width effect in the interface fracture during shear debonding of FRP sheets from concrete. Engineering Fracture Mechanics 74, No. 4, 578-594.

Viola, E. Belmonte C., Viola G. (2007). Lateral stress effect on fracture quantities in a piezoelectric medium. Key Engineering Materials 348- 349, 957-960.

Carloni C., Gentilini C., Nobile L. (2006). Buckling of thin-walled cracked columns. Key Engineering Materials 324-325, 1127-1130.

Piva A., Tornabene F., Viola E. (2006). Crack propagation in a four-parameter piezoelectric medium. European Journal of Mechanics - A/Solids 25, No. 2, 230-249.

Ricci P., Viola E., Di Leo A., Ferretti, E. (2006). Modelling and Analysis of Timoshenko Beams Weakened by Multiple Transverse Open Cracks. Proc. GIMC XVI, Bologna (Italy), 26-28 June.

Nobile L., Carloni C. (2005). Fracture analysis for orthotropic cracked plates. Composite Structures 68, No. 3, 285-293.

Research projects

SMooHS – Smart Monitoring of Historical Structures, Unity of Bologna, European Research project ENV.2007.3.2.1.1.

Relateds

Laboratory of Computational Mechanics - LAMC
Supports research and education in the area of Computational Mechanics and fosters advances in the development and application of numerical methods and computational techniques for the solution of engineering problems.
CIMEST
Centre of study and research on the identification of materials and structures - "Michele Capurso".