The role of the Gordon–Schowalter derivative term in the constitutive models—improved flexibility of the modified XPP model

This paper examines the free energy potentials of damaged solids for the construction of damage mechanics constitutive models. The physical meaning of free energy in solid mechanics is analyzed in contrast with that in traditional fields of thermodynamics; 1D stress-strain curves are used to show the relationships between various thermodynamic state functions in isothermal loading processes; and the role of plastic free energy in damage evolution is discussed both macroscopically and microscopically. It is concluded that plastic free energy, which is a macroscopic representation of some additional microscopic elastic energy, cannot do work during unloading but get released when damage takes place, constituting part of the driving force for damage evolution.

Download Full-text

DEM Study on Energy Allocation Behavior in Crushable Soils

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.871.119 ◽

2013 ◽

Vol 871 ◽

pp. 119-123

Author(s):

Jian Feng Wang ◽

Run Qiu Huang

Keyword(s):

Shear Bands ◽

Constitutive Models ◽

Energy Allocation ◽

Particle Breakage ◽

Large Strains ◽

Detailed Knowledge ◽

Soil Fabric ◽

Specimen Density ◽

Interparticle Friction

Detailed knowledge of particle-scale energy allocation behavior under the influence of particle breakage is of fundamental importance to the development of micromechanics-based constitutive models of sands. This paper reports original results of the energy input/dissipation of an idealized crushable soil using 3D DEM simulations. Particle breakage is modeled as the disintegration of synthetic agglomerate particles which are made up of parallel-bonded elementary spheres. Simulation results show that the initial specimen density and crushability strongly affect the energy allocation of the soil both at small and large strains. The major role of particle breakage, which itself only dissipates a negligible amount of input energy, is found to advance the soil fabric change and promote the interparticle friction dissipation. Particularly, at small strains, particle breakage disrupts the strain energy buildup and thus reduces the mobilized shear strength and dilatancy of a granular soil. At large strains where particle breakage is greatly reduced, a steady energy dissipation by interparticle friction and mechanical damping is observed. Furthermore, it is found that shear bands develop in most dense crushable specimens at large strains, but they are only weakly correlated to the anisotropy of the accumulated friction dissipation.

Download Full-text

Ancient Materials and Singular Constructions

Civil and Environmental Engineering ◽

10.4018/978-1-4666-9619-8.ch013 ◽

2016 ◽

pp. 340-359 ◽

Cited By ~ 1

Author(s):

Paloma Pineda

Keyword(s):

Building Materials ◽

Numerical Models ◽

Constitutive Models ◽

Seismic Loading ◽

Structural Behaviour ◽

Seismic Reliability ◽

Lack Of Information ◽

Analytical Strategies ◽

Heritage Buildings

Analysis and evaluation of seismic reliability of masonry cultural heritage buildings by means of numerical models is a difficult task, owing to uncertainties that mainly affect structural behaviour and mechanical material properties. The former includes lack of information on model definition -geometry, constraints, materials, constructive details...-, and the latter is focused on non-linear masonry behaviour and low tensile strength. Furthermore, if a comprehensive study of structural behaviour is going to be performed, accuracy and suitability of the analytical or numerical method selected are essential issues. For those reasons, multidisciplinary analyses combining numerical, experimental and heritage tools may be very useful to face the challenge of effective preservation. This chapter focuses on the role of the building materials as controllers of collapse phenomena under seismic loading. The first section is devoted to some heritage strategies that may be learnt from the wisdom of ancient builders. The second section focuses on numerical strategies, reviewing different constitutive models via FEM under seismic loading and analysing the role of the control parameters. That section provides a brief reflexion on different analytical strategies. Finally, as a way of conclusion, Strengths, Weaknesses, Opportunities and Threats (SWOT) analysis of historic building materials and associated techniques within a dynamic framework, by means of multidisciplinary tools is provided.

Download Full-text

Ancient Materials and Singular Constructions

Handbook of Research on Seismic Assessment and Rehabilitation of Historic Structures - Advances in Civil and Industrial Engineering ◽

10.4018/978-1-4666-8286-3.ch021 ◽

2015 ◽

pp. 629-648

Author(s):

Paloma Pineda

Keyword(s):

Building Materials ◽

Numerical Models ◽

Constitutive Models ◽

Seismic Loading ◽

Structural Behaviour ◽

Seismic Reliability ◽

Lack Of Information ◽

Analytical Strategies ◽

Heritage Buildings

Analysis and evaluation of seismic reliability of masonry cultural heritage buildings by means of numerical models is a difficult task, owing to uncertainties that mainly affect structural behaviour and mechanical material properties. The former includes lack of information on model definition -geometry, constraints, materials, constructive details...-, and the latter is focused on non-linear masonry behaviour and low tensile strength. Furthermore, if a comprehensive study of structural behaviour is going to be performed, accuracy and suitability of the analytical or numerical method selected are essential issues. For those reasons, multidisciplinary analyses combining numerical, experimental and heritage tools may be very useful to face the challenge of effective preservation. This chapter focuses on the role of the building materials as controllers of collapse phenomena under seismic loading. The first section is devoted to some heritage strategies that may be learnt from the wisdom of ancient builders. The second section focuses on numerical strategies, reviewing different constitutive models via FEM under seismic loading and analysing the role of the control parameters. That section provides a brief reflexion on different analytical strategies. Finally, as a way of conclusion, Strengths, Weaknesses, Opportunities and Threats (SWOT) analysis of historic building materials and associated techniques within a dynamic framework, by means of multidisciplinary tools is provided.

Download Full-text