Transient and Residual Stresses and Displacements in Self-Curing Bone Cement—Part I: Characterization of Relevant Volumetric Behavior of Bone Cement

1982 ◽  
Vol 104 (1) ◽  
pp. 21-27 ◽  
Author(s):  
A. M. Ahmed ◽  
W. Pak ◽  
D. L. Burke ◽  
J. Miller
Keyword(s):  
Thermal Expansion ◽  
Residual Stresses ◽  
Bone Cement ◽  
Coefficient Of Thermal Expansion ◽  
Stress Generation ◽  
Curing Process ◽  
Cooling Phase ◽  
Volumetric Behavior ◽  
Fixation System

In this first part of a two-part report, some aspects of the volumetric behavior of bone cement during its curing process are examined as a prelude to an analysis for the transient and residual stresses and displacements in stem fixation systems. Experiments show that stress generation in the cement is associated with its temperature while curing and that during the cooling phase, the stresses are mainly due to thermal as opposed to bulk shrinkage. The appropriate coefficient of thermal expansion of bone cement has been evaluated from measurements in a simulated fixation system in conjunction with a thermoelastic analysis.

Transient and Residual Stresses and Displacements in Self-Curing Bone Cement—Part II: Thermoelastic Analysis of the Stem Fixation System

1982 ◽  
Vol 104 (1) ◽  
pp. 28-37 ◽  
Author(s):  
A. M. Ahmed ◽  
R. Nair ◽  
D. L. Burke ◽  
J. Miller
Keyword(s):  
Adverse Effects ◽  
Residual Stresses ◽  
Bone Cement ◽  
Cancellous Bone ◽  
Thermal Stresses ◽  
Curing Process ◽  
Hardening Material ◽  
Cement Interface ◽  
Fixation System ◽  
Curing Cement

In this second part of a two-part report, an idealized model of the stem fixation system is analyzed to determine the adverse effects of the thermal stresses and displacements of bone cement during its curing process. The Shaffer-Levitsky stress-rate strain-rate law for chemically hardening material has been used. The results show that if the cement is surrounded by cancellous bone, as opposed to cortical bone, then transient tensile circumferential stresses in the cement and similar radial stresses at the stem/cement interface are generated. The former may cause flaws and voids within the still curing cement, while the latter may cause gaps at the interface.

scholarly journals Characterization of Residual Stresses in Veneering Ceramics for Prostheses with Zirconia Framework

2018 ◽  
Vol 29 (4) ◽  
pp. 347-353 ◽  
Author(s):  
Vagner Flávio Reginato ◽  
Daniel Takanori Kemmoku ◽  
Ricardo Armini Caldas¹ ◽  
Ataís Bacchi³ ◽  
Carmem Silvia Pfeifer ◽  
...  
Keyword(s):  
Residual Stresses ◽  
Coefficient Of Thermal Expansion ◽  
Three Dimensional ◽  
Maximum Principal Stress ◽  
The Finite Element Method ◽  
Three Dimensional Model ◽  
Linear Contraction ◽  
Cte Mismatch ◽  
Fixed Prosthesis

Abstract The aim of this study was to evaluate the influence of the coefficient of thermal expansion (CTE or α) and glass transition temperature (Tg) of three veneering ceramics used with zirconia frameworks of full-arch fixed prostheses. The generation of residual stresses and linear contraction after the simulation of the cooling process and mechanical loading were measured. The analysis was based on the finite element method in three-dimensional model of a maxillary full-arch fixed prosthesis with zirconia framework (e.max ZirCAD) and veneer by felsdpathic ceramics (GEC - IPS e.max Ceram, GVM - Vita VM9 and GLC - Lava Ceram). The linear contraction simulation was performed by cooling the structures from the Tg of each veneer ceramic at room temperature (25°C). A loading of 100 N on the occlusal region of the first molar was performed. The magnitude of the maximum principal stress (smax) and linear contraction were evaluated. The levels of CTE mismatch between veneering ceramics and framework showed no relevant influence on smax and linear contraction. The Tg values of the veneer ceramic showed to be directly proportional to amount of smax and linear contraction. The GEC presented the highest values of smax and linear contraction. The GVM and GLC did not present significant differences between them. In conclusion, GVM was similar to GLC, while GEC presented differences in relation to other veneer ceramics in terms of residual stress and linear contraction.

scholarly journals On Residual Stresses Development during Nitriding of Steel: Thermochemical and Time Dependence

2010 ◽  
Vol 89-91 ◽  
pp. 256-261 ◽  
Author(s):  
Sebastien Jegou ◽  
Regis Kubler ◽  
Laurent Barrallier
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Time Dependence ◽  
Volume Change ◽  
Stress Generation ◽  
X Rays ◽  
Microstructural Effects

This work deals with the development of residual stresses during nitriding of steels. The main features of a chemico-thermo-echanical model of nitriding are presented. A micro-macroapproach is applied based on volume change computation in agreements with thermochemical modifications. Results are correlated with the characterization of a ternary Fe-C-3w.%Cr alloy nitrided at 550°C for various time. Residual stress-depth analyses are carried out by X-rays diffraction. Residual stress generation is deeply dependant on chemical and thermodynamical evolutions during the treatment, taking advantage on microstructural effects.

Mathematical Modeling on the Residual Stresses in Coatings Due to Heat Treatments

2020 ◽  
Vol 978 ◽  
pp. 514-521
Author(s):  
M.K. Srinath ◽  
M.S. Ganesha Prasad
Keyword(s):  
Residual Stresses ◽  
Coefficient Of Thermal Expansion ◽  
Thermal Strain ◽  
Heat Treatments ◽  
Air Cooling ◽  
Elastic Plastic ◽  
Strain Components ◽  
Cooling Phase ◽  
The Difference ◽  
Plasticity Coefficient

Coatings are implemented on engineering metals and alloys to augment the surface properties such as hardness as well as resistance to wear and corrosion. Heat treatments of coated metals/alloys are performed to aid in the progress of the bonding of the coatings to the substrate. During the air cooling process, the difference in the compositions of the coating and the substrate materials causes them to cool at different rates, which leads to straining in them. The paper presents the research on the mathematical investigation to evaluate the residual stresses in coatings caused due to heat treatments and subsequent air cooling. The mathematical modelling is executed to formulate the equations to represent the residual stresses retained in the coatings due to the heat treatments and subsequent air cooling. Air cooling undergoes two stages namely the initial quenching phase and the final cooling phase. During the quenching phase, the strain was expressed by considering the elastic, plastic and thermal strain components. Poisson’s ratio, deviatoric stress differential of the modulus of plasticity, coefficient of thermal expansion and change in temperature are used to express the elastic, plastic and thermal strain components. During the final cooling phase, the strain was expressed by considering only the elastic and thermal stain components, as the plastic staining the coating material generally does not occur during the final cooling phase and occurs only during the initial quenching phase. From the strain components, the residual stresses for the coatings in the x, y and z axis were formulated. Thus, the total residual stress is the sum total of stresses caused during the initial quenching phase and the final cooling phase.

Synthesis of Ca-Al-Si-O Compounds from Local Wastes

2009 ◽  
Vol 620-622 ◽  
pp. 121-124
Author(s):  
U.Sangwanna Sanewirush ◽  
P. Saewong
Keyword(s):  
Thermal Conductivity ◽  
Thermal Expansion ◽  
Rice Husk Ash ◽  
Coefficient Of Thermal Expansion ◽  
Ternary Diagram ◽  
Alumina Ceramics ◽  
Calcium Aluminosilicate ◽  
Pulp Production ◽  
Aluminum Anodizing

The local wastes, which are sources of SiO2, Al2O3 and CaO, are rice husk ash, waste sediment from aluminum anodizing process and dreg from pulp production, respectively. The wastes are mixed in three different compositions in ranges of 20-50 SiO2, 20-35 CaO and 20-45 Al2O3, wet milled, slip casted and then fired at 1,100 °C. Characterization of the fired bodies reveals the formation of calcium-aluminosilicate compounds: gehlenite and anorthite as major phases, in accordance with the SiO2-CaO-Al2O3 ternary diagram. Their bulk densities and % water absorption lies between 0.95-1.42 g/cm3 and 37.40-67.95%, respectively. While flexural strength and coefficient of thermal expansion are between 4.09-9.56 MPa and 6.14 - 10.1 x 10-6 °C-1, respectively. By simple thermal conductivity comparison, the materials themselves have thermal conductivity comparable to alumina ceramics. These wastes, therefore, may be used as precursors for the production of some insulating refractory members, in place of minerals from natural resources.

Micro and Macroscopic Approaches to Residual Stress Generation Mechanism of Thermal Spray Coatings

2000 ◽  
Author(s):  
S. Tobe ◽  
Y. Andou ◽  
M. Ando ◽  
S. Kuroda ◽  
K. Akita
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Thermal Spray ◽  
Stress Measurement ◽  
Coefficient Of Thermal Expansion ◽  
Steel Substrate ◽  
Generation Mechanism ◽  
Thermal Spray Coatings ◽  
Stress Generation ◽  
Spray Coatings

Abstract Microscopic and macroscopic residual stress measurements and a finite element method (FEM) for stress analysis of thermal spray coatings have been carried out to investigate the residual stress generation mechanism. The residual stresses of one splat, laminated two splats and coatings were measured by a micro-beam x-ray stress measurement system and the macroscopic residual stresses were measured in-situ by the curvature change of the thin substrate plate during and after spraying. Two coating materials were employed in this study to deposit the coatings. One is molybdenum of which the coefficient of thermal expansion (CTE) is smaller than that of steel substrate and the other is 80%Ni-20%Cr alloy which has higher CTE than steel. The substrate was preheated up to 550°C just before spraying. The residual stresses of the splat and a coating are fundamentally the same level. The FEM analysis on the residual stress was also useful and by the comparison of two measurement results of microscopic and macroscopic residual stresses, the generation mechanism was discussed.

Influence of thermal properties on residual stresses in SLM of aerospace alloys

2020 ◽  
Vol 26 (1) ◽  
pp. 213-222 ◽  
Author(s):  
Mostafa Yakout ◽  
M.A. Elbestawi ◽  
S.C. Veldhuis ◽  
S. Nangle-Smith
Keyword(s):  
Residual Stress ◽  
Stainless Steel ◽  
Thermal Expansion ◽  
Residual Stresses ◽  
Coefficient Of Thermal Expansion ◽  
Numerical Results ◽  
Stainless Steel 316L ◽  
Plate Removal ◽  
Content Type ◽  
Part Distortion

Purpose Residual stresses are induced during selective laser melting (SLM) because of rapid melting, solidification and build plate removal. This paper aims to examine the thermal cycle, residual stresses and part distortions for selected aerospace materials (i.e. Ti-6Al-4V, stainless steel 316L and Invar 36) using a thermo-mechanical finite element model. The numerical results are validated and compared to experimental data. Design/methodology/approach The model predicts the residual stress and part distortion after build plate removal. The residual stress field is validated using X-ray diffraction method and the part distortion is validated using dimensional measurements. Findings The trends found in the numerical results agree with those found experimentally. Invar 36 had the lowest tensile residual stresses because of its lowest coefficient of thermal expansion. The residual stresses of stainless steel 316L were lower than those of Ti-6Al-4V because of its high thermal diffusivity. Research limitations/implications The model predicts residual stresses at the optimal SLM process parameters. However, using any other process conditions could cause void formation and/or alloying element vaporization, which would require the inclusion of melt pool physics in the model. Originality/value The paper explains the influence of the coefficient of thermal expansion and thermal diffusivity on the induced thermal stresses using experimental and numerical results. The methodology can be used to predict the part distortions and residual stresses in complex designs of any of the three materials under optimal SLM process parameters.

scholarly journals A Comparative Study on the Characterization of Nanofibers with Cellulose I, I/II, and II Polymorphs from Wood

Polymers ◽  
2019 ◽  
Vol 11 (1) ◽  
pp. 153 ◽  
Author(s):  
Haiying Wang ◽  
Suiyi Li ◽  
Tiantian Wu ◽  
Xiaoxuan Wang ◽  
Xudong Cheng ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Comparative Study ◽  
Coefficient Of Thermal Expansion ◽  
Cellulose Nanofibers ◽  
High Yield ◽  
Chemical Extraction ◽  
Cellulose Content ◽  
Cellulose I ◽  
Aspect Ratios

Polymorphic changes in cellulose nanofibers (CNFs) are closely related to their properties and applications, and it is of interest to investigate how polymorphic changes influence their properties. A comparative study on the properties of CNFs with cellulose I, I/II, and II polymorphs from wood was conducted herein. CNFs were obtained by chemical extraction combined with a simple and efficient mechanical treatment (one pass through a grinder). This process resulted in a relatively high yield of 80–85% after a simple grinding treatment. The polymorphic changes in the CNFs and the chemical composition, morphology, tensile performances, and thermal properties were systematically characterized and compared. The X-ray diffraction and FTIR analyses verified the existence of three types of purified pulps and CNFs with cellulose I, cellulose I/II, and cellulose II polymorphs (CNF-I, CNF-I/II, CNF-II). Morphological observations presented that these three types of CNFs all exhibited high aspect ratios and entangled structures. Tensile testing showed that the CNF films all exhibited high tensile strengths, and the fracture strains of the CNF-I/II (11.8%) and CNF-II (13.0%) films were noticeably increased compared to those of the CNF-I film (6.0%). If CNF-II is used as reinforcing material, its larger fracture strain can improve the mechanical performance of the CNF composites, such as fracture toughness and impact strength. In addition, CNF-I, CNF-I/II, and CNF-II films showed very low thermal expansion in the range 20–150 °C, with the coefficient of thermal expansion values of 9.4, 17.1, and 17.3 ppm/K, respectively. Thermogravimetric analysis (TGA) revealed that the degradation temperature of CNF-I and CNF-II was greater than that of CNF-I/II, which was likely due to increased α-cellulose content. This comparative study of the characterization of CNF-I, CNF-I/II, and CNF-II provides a theoretical basis for the application of CNFs with different polymorphs and could broaden the applications of CNFs.

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