Sökning: "thermal dilation"

Visar resultat 1 - 5 av 6 avhandlingar innehållade orden thermal dilation.

1. 1. Thermal Crack Risk Estimation and Material Properties of Young Concrete

   Författare :Anders Hösthagen; Jan-Erik Jonasson; Mårten Larson; Luleå tekniska universitet; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Thermal cracking risk; young concrete; Equivalent Restraint Method; strength development; heat of hydration; creep; shrinkage; thermal dilation; modeling; field observations; Structural Engineering; Konstruktionsteknik;

   Sammanfattning : This thesis presents how to establish a theoretical model to predict risk of thermal cracking in young concrete when cast on ground or an arbitrary construction. The crack risk in young concrete is determined in two steps: 1) calculation of temperature distribution within newly cast concrete and adjacent structure; 2) calculation of stresses caused by thermal and moisture (due to self-desiccation, if drying shrinkage not included) changes in the analyzed structure. LÄS MER

3. 2. Macroscopic Volume and Free Volume of Polymer Blends and Pressure-densified Polymers

   Författare :Marcus Schmidt; Chalmers tekniska högskola; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; free-volume theories; refractive index; Lorentz-Lorenz equation; loss tangent; Avrami equation; freezing fractions; copolymers; polymer blends; pressure dilatometry; Tait equation of state; free-volume distributions; pressure-densified polymers; entropy of melting; dynamic-mechanical analysis; positronium; positron annihilation; free volume; cavity size; polymers; bulk modulus; PVT; phase separation; compressibility; thermal expansivity;

   Sammanfattning : The macroscopic volume V as a function of pressure P and temperature T is obtained from PVT measurements. PVT data is sensitive to the state of polymers and changes therein. Moreover, PVT data gives access to the free-volume fraction. LÄS MER

4. 3. Measurement and modelling of young concrete properties

   Författare :Peter Fjellström; Christer Isgren; Luleå tekniska universitet; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Structural Engineering; Konstruktionsteknik;

   Sammanfattning : The main aim of this thesis is to refine models for strength and heat development of the young concrete, and evaluate if developed models at Luleå University of Technology (LTU) for creep, autogenous shrinkage and thermal dilation needs refinement. These are of importance in hardening control and in crack control of a concrete structure. LÄS MER

5. 4. Fractured Rock Masses as Equivalent Continua - A Numerical Study

   Författare :Ki-Bok Min; KTH; []
   Nyckelord :fractured rock masses; equivalent continuum; discrete fracture Network DFN ; Distinct Element Method DEM ; Finite Element Method FEM ; Nuclear Waste Disposal; Coupled Thermo-Hydro-Mechanical Processes;

   Sammanfattning : In this thesis, fractured rock masses are treated asequivalent continua for large-scale analyses of rockengineering projects. Systematic developments are made for thedetermination of equivalent mechanical and hydraulic propertiesof fractured rock masses using a hybrid discrete fracturenetwork - distinct element method (DFN-DEM) approach. LÄS MER

7. 5. Quantitative image analysis : a focus on automated characterization of structures in optical microscopy of iron ore pellets

   Författare :Frida Nellros; Carolina Wählby; Luleå tekniska universitet; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Signalbehandling; Signal Processing;

   Sammanfattning : Sintering occurs in many types of material such as iron, ceramics and snow, typically during thermal treatment, and aects the material properties, particularly the strength, by the bonding of particles into a coherent structure. In order to improve the mechanical strength in magnetite iron ore pellets it is important to be able to characterize and quantitatively measure the degree of sintering and features that impact the process of sintering. LÄS MER