A numerical model for the time‐dependent cracking of cementitious materials

2001 ◽  
Vol 52 (7) ◽  
pp. 637-654 ◽  
Author(s):  
G. P. A. G. van Zijl ◽  
R. de Borst ◽  
J. G. Rots
Keyword(s):  
Numerical Model ◽  
Cementitious Materials ◽  
Time Dependent

scholarly journals Dynamic Pulse Buckling of Composite Stanchions in the Sub-Cargo Floor Area of a Civil Regional Aircraft

Materials ◽  
2020 ◽  
Vol 13 (16) ◽  
pp. 3594
Author(s):  
Andrea Sellitto ◽  
Francesco Di Caprio ◽  
Michele Guida ◽  
Salvatore Saputo ◽  
Aniello Riccio
Keyword(s):  
Numerical Model ◽  
Numerical Models ◽  
Low Frequency ◽  
Time Dependent ◽  
Structural Behavior ◽  
Cyclic Loads ◽  
Civil Aircraft ◽  
Compressive Loads ◽  
Pulse Buckling ◽  
Implicit And Explicit

This work is focused on the investigation of the structural behavior of a composite floor beam, located in the cargo zone of a civil aircraft, subjected to cyclical low-frequency compressive loads with different amplitudes. In the first stage, the numerical models able to correctly simulate the investigated phenomenon have been defined. Different analyses have been performed, aimed to an exhaustive evaluation of the structural behavior of the test article. In particular, implicit and explicit analyses have been considered to preliminary assess the capabilities of the numerical model. Then, explicit non-linear analyses under time-dependent loads have been considered, to predict the behavior of the composite structure under cyclic loading conditions. According to the present investigation, low-frequency cyclic loads with peak values lower than the static buckling load value are not capable of triggering significant instability.

A Consistent Approach for the Development of a Comprehensive Data Base of Time-Dependent Parameters for Concrete Engineered Barriers

2013 ◽  
Author(s):  
Suresh C. Seetharam ◽  
Dirk Mallants ◽  
Janez Perko ◽  
Diederik Jacques
Keyword(s):  
Data Base ◽  
Experimental Studies ◽  
Cementitious Materials ◽  
Time Dependent ◽  
Extensive Literature ◽  
Near Surface ◽  
Comprehensive Data ◽  
Engineered Barriers ◽  
Parameter Values ◽  
Consistent Approach

This paper presents a consistent approach for the development of a comprehensive data base of time-dependent hydraulic and transport parameters for concrete engineered barriers of the future Dessel near surface repository for low level waste. The parameter derivation is based on integration of selected data obtained through an extensive literature review, data from experimental studies on cementitious materials specific for the Dessel repository and numerical modelling using physically-based models of water and mass transport. Best estimate parameter values for assessment calculations are derived, together with source and expert range and their probability density function wherever the data was sufficient. We further discuss a numerical method for upscaling laboratory derived parameter values to the repository scale; the resulting large-scale effective parameters are commensurate with numerical grids used in models for radionuclide migration. To accommodate different levels of conservatism in the various assessment calculations defined by ONDRAF/NIRAS, several sets of parameter values have been derived based on assumptions that introduce different degrees of conservatism. For pertinent parameters, the time evolution of such properties due to the long-term concrete degradation is also addressed. The implementation of the consistent approach is demonstrated by considering the pore water diffusion coefficient as an example.

The Effect of Thermal Field on the Deposition of Fe-TiC on Carbon Steel Using Laser Cladding

2010 ◽  
Author(s):  
Masoud Alimardani ◽  
Ali Emamian ◽  
Amir Khajepour ◽  
Stephen F. Corbin
Keyword(s):  
Carbon Steel ◽  
Numerical Model ◽  
Laser Cladding ◽  
Thermal Field ◽  
Deposition Process ◽  
Time Dependent ◽  
Experimental Investigations ◽  
Thermal Fields ◽  
Temperature Distributions ◽  
Laser Cladding Process

In this paper, a numerical and experimental method is used to investigate the effect of thermal fields on the deposition of Fe-TiC using the laser cladding process. Since in laser cladding temperature distributions and consequent rapid cooling rates determine the microstructure and final physical properties of the deposited layers, a 3D time-dependent numerical model is used to simulate the cladding process parallel to experimental analysis. The numerical results are used to study the temperature distributions and their evolutions throughout the deposition process. The experimental and verified numerical outcomes are then employed to study the variations of the microstructures of the deposited material as well as correlation between the formed microstructures and temperature distributions across the deposition domain. The numerical and experimental investigations are conducted through the deposition of Fe-TiC on the substrate of AISI 1030 carbon steel using a 1.1 kW fiber laser. The experimental results confirm that by increasing the substrate temperature throughout the process the distribution of the TiC particles changes along with the deposited tracks and the TiC particles start forming clusters at the top of the clad.

3-D time-dependent numerical model of flow patterns within a large-scale Czochralski system

2008 ◽  
Vol 310 (7-9) ◽  
pp. 2126-2133 ◽  
Author(s):  
Phil-Ouk Nam ◽  
Sang-Kun O ◽  
Kyung-Woo Yi
Keyword(s):  
Numerical Model ◽  
Large Scale ◽  
Flow Patterns ◽  
Time Dependent
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