Damage modelling Research Papers - Academia.edu (original) (raw)

After a brief introduction on the research project RiSEM (Seismic Risk of Monumental Buildings), the paper discusses on the seismic assessment of historic masonry towers according to the Italian ''Guidelines for the assessment and mitigation of the seismic risk of the cultural heritage'' that identifies an analysis methodology based on three different levels of evaluation, according to an increased knowledge of the structure. The RiSEM project aimed at developing and testing innovative and expeditious methodologies (i.e. either without or with a minimal direct contact with the masonry building) to evaluate all the main structural features of the monumental buildings required for the assessment of their seismic safety. As a relevant case study the ''Town of Fine Towers'', San Gimignano (Italy), listed under the UNESCO World Cultural Heritage Sites, was selected. The paper summarizes the analyses performed on one of the San Gimignano towers: the Coppi-Campatelli one. The seismic vulnerability of the tower was evaluated with reference to the above guidelines, and the paper reports and critically compares the results obtained for the three levels of evaluation there defined: LV1 (analysis at territorial level), LV2 (local analysis) and LV3 (global analysis).

- by and +1
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- Finite element modelling, Seismic Risk Assessment, Damage modelling, Static Non-linear Analysis

Dual-Phase steel is an advanced high strength steel that
are used recently in auto-body for energy absorption.
Fracture is an noticeable factor in crashworthiness of
vehicle impact loading. Failure prediction of DP800 was
investigated in this studying. There are different fracture
criteria for damage modeling, but the material behavior
cannot be simulated by using them, so a new approach
have been used in this studying. The Gurson model in
conjunction with the Johnson-Cook damage model is
applied to simulate correctly the material behavior. By
using a new method in this research, in shear fracture
and ductile fracture the active mechanisms are JohnsonCook damage model and Gurson model respectively.
Finally, the crashworthiness of a B-Pillar in different
conditions is simulated and the fracture is predicted.

- by solat noruzi
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- Damage modelling, Dual phase steels, Gurson

A proposed damage model is used for investigating the deformation and interfacial failure behavior of an adhesively bonded single-lap thick joint made of S2 glass/SC-15 epoxy resin composite material. The bonding material is 3M Scotch-Weld Epoxy Adhesive DP405 Black. Continuum damage mechanics models are used to describe the damage initiation and final failure at or near the interface. The effect of adhesive overlap length, thickness, and plasticity on the interfacial shear and normal stresses is studied. Experimental and analytical data are used to validate the proposed damage models.

- by Jianghui Mao
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- Plasticity, Damage modelling, Damage Evolution, Damage Propagation

Thermal barrier coatings (TBCs) are advanced material systems used to enhance performance and in-service life of components operated at high temperatures in gas turbines and other power-generation devices. Because of complexity, numerical methods became important tools both for design of these coatings and for in-service life estimations and optimization. In this contribution, two main features that affect the TBCs’ performance, namely the roughness of the bond coat and the microstructure of the ceramic top coat, are discussed based on Finite Element Method (FEM) and Finite Element Microstructure MEshfree (FEMME) simulations that were used to calculate stresses and assess damage within the coating. Roughness data obtained from plasma-sprayed CoNiCrAlY + YSZ coated samples are supplemented to discuss assumptions and results of employed numerical models.

- by K. Slámečka and +1
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- Numerical Modelling, Plasma spray coatings, Damage modelling

The concept of underwater turbine, called tidal current turbine, designates the device which allows the conversion of kinetic energy produced by marine currents into electric energy. This study shows that the world of marine propellers presents an interesting avenue of research with regard to the hydrodynamic behaviour of tidal current turbines. As a marine propeller has to be adapted to a specific ship, a tidal current turbine has to be adapted to a specific site [1]. We chose the most promising site on the French coasts, the race of Alderney. The main numerical tool is a propeller code based on the potential flow model. Putting aside the structure constraints, the design of tidal turbine is restricted by the hydrodynamic efficiency which means that flow separation and cavitation occurrence have to be avoided. An optimization procedure has allowed us to obtain a bare turbine geometry presenting a power coefficient (Cp) reaching 88% of the Betz (see (a)) and avoiding cavitation (see

- by Mahrez AIT and +1
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- Composite Materials and Structures, Damage Mechanics, Tidal turbine, Damage modelling

A 2D lattice approach to describe hydraulic fracturing is presented. The interaction of fluid pressure and mechanical response is described by Biot’s theory. The lattice model is applied to the analysis of a thick-walled cylinder, for which an analytical solution for the elastic response is derived. The numerical results obtained with the lattice model agree well with the analytical solution. Furthermore, the coupled lattice approach is applied to the fracture analysis of the thick-walled cylinder. It is shown that the proposed lattice approach provides results that are independent of the mesh size. Moreover, a strong geometrical size effect on nominal strength is observed which lies between analytically derived lower and upper bounds. This size effect decreases with increasing Biot’s coefficient.

- by Domenico Gallipoli
- •
- Structural Engineering, Geomechanics, Concrete, Fluid flow in porous media

Thermal barrier coatings (TBCs) are advanced material systems used to enhance performance and in-service life of components operated at high temperatures in gas turbines and other power-generation devices. Because of complexity, numerical methods became important tools both for design of these coatings and for in-service life estimations and optimization. In this contribution, two main features that affect the TBCs' performance, namely the roughness of the bond coat and the microstructure of the ceramic top coat, are discussed based on Finite Element Method (FEM) and Finite Element Microstructure MEshfree (FEMME) simulations that were used to calculate stresses and assess damage within the coating. Roughness data obtained from plasma-sprayed CoNiCrAlY + YSZ coated samples are supplemented to discuss assumptions and results of employed numerical models.

- by James Marrow
- •
- Materials Science, Numerical Modelling, Plasma spray coatings, Damage modelling

Damage models for natural hazards are used for decision making on reducing and transferring risk. The damage estimates from these models depend on many variables and their complex sometimes nonlinear relationships with the damage. In recent years, data-driven modeling techniques have been used to capture those relationships. The available data to build such models are often limited. Therefore, in practice it is usually necessary to transfer models to a different context. In this article, we show that this implies the samples used to build the model are often not fully representative for the situation where they need to be applied on, which leads to a "sample selection bias." In this article, we enhance data-driven damage models by applying methods, not previously applied to damage modeling, to correct for this bias before the machine learning (ML) models are trained. We demonstrate this with case studies on flooding in Europe, and typhoon wind damage in the Philippines. Two sample selection bias correction methods from the ML literature are applied and one of these methods is also adjusted to our problem. These three methods are combined with stochastic generation of synthetic damage data. We demonstrate that for both case studies, the sample selection bias correction techniques reduce model errors, especially for the mean bias error this reduction can be larger than 30%. The novel combination with stochastic data generation seems to enhance these techniques. This shows that sample selection bias correction methods are beneficial for damage model transfer.

This work presents a numerical study of the impact behaviour of an all composite ducted tidal turbine. The numerical analysis has been performed by means of advanced numerical models implemented into Abaqus/Explicit. The modelling procedure in term of intralaminar damage model was implemented using the VUMAT subroutine which has been validated through comparison with experimental data available. A submodeling approach has been used to reduce significantly the computational time. The main objective of the numerical approach presented in this study is to propose a structural design methodology leading to improve the design efficiency and reduce the certifications cost of ducted tidal turbine, keeping in mind a commercial scalability of the MJM concept (Mahrez-Mostapha &Jean-Marc design). The proposed approach reveals some interesting points concerning the severity of the impact damage and the safety of the duct.

- by Mahrez AIT and +2
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- Structural Engineering, Composite Materials and Structures, Marine Renewable Energy, Numerical Analysis