Reliability of Thermally Loaded Cylinders

1990 ◽  
Vol 112 (3) ◽  
pp. 303-308 ◽  
Author(s):  
H. S. Zibdeh
Keyword(s):  
Thermal Stresses ◽  
Coefficient Of Thermal Expansion ◽  
Perturbation Technique ◽  
Outer Radius ◽  
Temperature Gradients ◽  
Normal Distributions ◽  
Inner Radius ◽  
Thermal Changes ◽  
Log Normal ◽  
Outer Half

Cylinders often contain fluids at various temperatures. Temperature gradients develop across the cylinder which in turn produce thermal stresses. Using a perturbation technique, expressions for means and standard deviations of thermal stresses in cylinders are presented in this paper. These expressions include the probabilistic effects of changes due to inner and outer radii, modulus of elasticity, Poisson’s ratio, coefficient of thermal expansion, and temperature. It is found out that the cylinder is more sensitive to the geometrical changes than the mechanical and thermal changes. It is also noticed that the effect of variation in the inner radius is more than the outer radius at the inner half of the cylinder. On the other hand, the effect of variation in the outer radius is more than the inner radius at the outer half of the cylinder. Probabilities of failure are calculated for normal and log-normal distributions.

scholarly journals Transient Thermoelastic Analysis of Pressurized Rotating Disks Subjected to Arbitrary Boundary and Initial Conditions

2014 ◽  
Vol 2014 ◽  
pp. 1-13 ◽  
Author(s):  
Mohammad Zamani Nejad ◽  
Azam Afshin
Keyword(s):  
Thermal Stresses ◽  
Initial Conditions ◽  
Exact Analytical Solution ◽  
Separation Of Variables ◽  
Outer Radius ◽  
Rotating Disks ◽  
Arbitrary Boundary ◽  
Inner Radius ◽  
Transient Thermal

This paper focuses on exact analytical solution of transient thermoelastic behaviors of rotating pressurized disks subjected to arbitrary boundary and initial conditions. The pressure, inner radius, and outer radius are considered constant. The basic thermoelasticity theory under generalized assumptions is used to solve the thermoelastic problem. Using the method of the separation of variables, the relations of temperature and transient thermal stresses in the radial direction are obtained. In the case study, the disk is considered under heat flux. Some useful discussions and numerical examples are presented. The analytical results were compared with those of the finite element method and good agreement was found. The relations obtained in this paper can be applied to any arbitrary boundary and initial conditions.

Study of DGEBA and Novolac Adhesive Solutions between Ceramic and Steel Substrates

2010 ◽  
Vol 112 ◽  
pp. 37-47
Author(s):  
Clélia Gaussens ◽  
Valérie Nassiet ◽  
Bouchra Hassoune-Rhabbour
Keyword(s):  
Thermal Stresses ◽  
Coefficient Of Thermal Expansion ◽  
Thermal Tests ◽  
Wide Range ◽  
Thermal Changes ◽  
Formulation Parameters ◽  
Novolac Epoxy ◽  
Structural Adhesive ◽  
Adhesive Formulation ◽  
Steel Substrates

The industrial application (under a confidential clause) concerns a ceramic/steel assembly. This PhD research is concerned with providing a reliable industrial bonding between ceramic and steel using structural adhesive. This industrial joint shall withstand a wide range of temperatures with brutal thermal changes. This paper focuses on the adhesive formulation. Indeed, we needed to compromise the adhesive flexibility: soft enough to resist the thermal stresses and compensate the coefficient of thermal expansion mismatch between the two substrates. We find this good compromise with DGEBA and Novolac epoxy based adhesive separated or blended. The influence of the different formulation parameters on the initial properties was studied by chemical, rheological and thermal tests on adhesive samples. Depending on those formulations, we observed different behaviours in term of glass transition temperature, cross-linking time and flexibility.

Deformation at interfaces of Ti-6Al-4V/SiC fiber composites

1992 ◽  
Vol 50 (1) ◽  
pp. 158-159
Author(s):  
Warren J. Moberly ◽  
Daniel B. Miracle ◽  
S. Krishnamurthy
Keyword(s):  
Thermal Stresses ◽  
Load Transfer ◽  
Coefficient Of Thermal Expansion ◽  
Hot Isostatic Pressing ◽  
Matrix Composites ◽  
Ongoing Research ◽  
Aerospace Applications ◽  
Sic Fiber ◽  
The Matrix ◽  
Intermetallic Matrix Composites

Titanium-aluminum alloy metal matrix composites (MMC) and Ti-Al intermetallic matrix composites (IMC), reinforced with continuous SCS6 SiC fibers are leading candidates for high temperature aerospace applications such as the National Aerospace Plane (NASP). The nature of deformation at fiber / matrix interfaces is characterized in this ongoing research. One major concern is the mismatch in coefficient of thermal expansion (CTE) between the Ti-based matrix and the SiC fiber. This can lead to thermal stresses upon cooling down from the temperature incurred during hot isostatic pressing (HIP), which are sufficient to cause yielding in the matrix, and/or lead to fatigue from the thermal cycling that will be incurred during application, A second concern is the load transfer, from fiber to matrix, that is required if/when fiber fracture occurs. In both cases the stresses in the matrix are most severe at the interlace.

Log-normal distributions in parasitology

1984 ◽  
Vol 93 (6) ◽  
pp. 591-598 ◽  
Author(s):  
Sandeep K Malhotra
Keyword(s):  
Normal Distributions ◽  
Log Normal

Improved Diffuser/Volute Combinations for Centrifugal Compressors

2008 ◽  
Vol 130 (1) ◽  
Author(s):  
T. Steglich ◽  
J. Kitzinger ◽  
J. R. Seume ◽  
R. A. Van den Braembussche ◽  
J. Prinsier
Keyword(s):  
Cross Sections ◽  
Pressure Ratio ◽  
Pressure Rise ◽  
Outer Radius ◽  
Inner Radius ◽  
Pressure Pipeline ◽  
The Cross ◽  
Improved Performance ◽  
High Pressure Pipeline ◽  
Original Configuration

Internal volutes have a constant outer radius, slightly larger than the diffuser exit radius, and the circumferential increase of the cross section is accommodated by a decrease of the inner radius. They allow the design of compact radial compressors and hence are very attractive for turbochargers and high-pressure pipeline compressors, where small housing diameters have a favorable impact on weight and cost. Internal volutes, however, have higher losses and lower pressure rise than external ones, in which the center of the cross sections is located at a larger radius than the diffuser exit. This paper focuses on the improvement of the internal volute performance by taking into account the interaction between the diffuser and the volute. Two alternative configurations with enhanced aerodynamic performance are presented. The first one features a novel, nonaxisymmetric diffuser̸internal volute combination. It demonstrates an increased pressure ratio and lower loss over most of the operating range at all rotational speeds compared with a symmetric diffuser̸internal volute combination. The circumferential pressure distortion at off design operation is slightly larger than in the original configuration with a concentric vaneless diffuser. Alternatively, a parallel-walled diffuser with low-solidity vanes and an internal volute allows a reduction of the unsteady load on the impeller and an improved performance, approaching that of a vaneless concentric diffuser with a large external volute.

Finite Element Analysis of Thermal Stresses in Circumferential Cast Clasps of Removable Partial Dentures

2007 ◽  
Vol 23 ◽  
pp. 229-232
Author(s):  
Liliana Sandu ◽  
Nicolae Faur ◽  
Cristina Bortun ◽  
Sorin Porojan
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Thermal Stresses ◽  
Element Analysis ◽  
3 Dimensional ◽  
Thermal Changes ◽  
The Finite Element Analysis ◽  
Dimensional Finite Element ◽  
Back Action ◽  
Aggressive Effect

Several studies evaluated the removable partial dentures by the finite element analysis, but none of them evaluated thermal stresses. The purpose of the study was to explore the influence of thermal oral changes induced by hot/cold liquids and food on the circumferential cast clasps of removable partial dentures. A 3-dimensional finite element method was used to explore the temperature distribution, thermal stress and the influence of thermal changes on stresses and displacements of circumferential clasps during functions. Thermal variations induce stresses in dental clasps, high temperatures having a more aggressive effect than lower one. Cold liquids and food induce high stresses in the retentive clasp arms while hot ones in the occlusal rests of the clasps and for the back action clasp also in the minor connector. The study suggests the importance of consFigureidering thermal variations for stress analyses of the cast clasps.

Numerical Study of Thermal Stresses in a Planar Solid Oxide Fuel Cell Stack

2017 ◽  
Author(s):  
Cun Wang ◽  
Tao Zhang ◽  
Cheng Zhao ◽  
Jian Pu
Keyword(s):  
Thermal Stress ◽  
Fuel Cell ◽  
Solid Oxide Fuel Cell ◽  
Thermal Stresses ◽  
Coefficient Of Thermal Expansion ◽  
Numerical Study ◽  
Solid Oxide ◽  
Oxide Fuel ◽  
Compressive Loads ◽  
Cte Mismatch

A three dimensional numerical model of a practical planar solid oxide fuel cell (SOFC) stack based on the finite element method is constructed to analyze the thermal stress generated at different uniform temperatures. Effects of cell positions, different compressive loads, and coefficient of thermal expansion (CTE) mismatch of different SOFC components on the thermal stress distribution are investigated in this work. Numerical results indicate that the maximum thermal stress appears at the corner of the interface between ceramic sealants and cells. Meanwhile the maximum thermal stress at high temperature is significantly larger than that at room temperature (RT) and presents linear growth with the increase of operating temperature. Since the SOFC stack is under the combined action of mechanical and thermal loads, the distribution of thermal stress in the components such as interconnects and ceramic sealants are greatly controlled by the CTE mismatch and scarcely influenced by the compressive loads.

On the Vibration of a Rotating Disk

1972 ◽  
Vol 39 (4) ◽  
pp. 1143-1144 ◽  
Author(s):  
S. Barasch ◽  
Y. Chen
Keyword(s):  
Approximate Calculation ◽  
Initial Conditions ◽  
Rotating Disk ◽  
Equation Of Motion ◽  
Outer Radius ◽  
Order Equation ◽  
System Of Differential Equations ◽  
Fourth Order Equation ◽  
First Order ◽  
Inner Radius

The equation of motion of a rotating disk, clamped at the inner radius and free at the outer radius, is solved by reducing the fourth-order equation of motion to a set of four first-order equations subject to arbitrary initial conditions. A modified Adams’ method is used to numerically integrate the system of differential equations. Results show that Lamb-Southwell’s approximate calculation of the frequency is justified.

scholarly journals Geometric nonlinear analysis of thin elastic paraboloid of revolution shaped shells with radial waves

2020 ◽  
Vol 21 (3) ◽  
pp. 208-214
Author(s):  
Mathieu Gil-oulbé ◽  
Aleksey S. Markovich ◽  
Prosper Ngandu ◽  
Svetlana V. Anosova
Keyword(s):  
Sheet Material ◽  
Outer Radius ◽  
Contact Boundary ◽  
Load Parameter ◽  
Spatial Form ◽  
Structural Behaviour ◽  
Inner Radius ◽  
Paraboloid Of Revolution ◽  
Different Types ◽  
Loaded State

From the old ancient types of roof and dome construction, various forms of shells have been discovered which attract special attention. A shell is a structure composed of sheet material so that the curvature plays an important role in the structural behaviour, realizing its spatial form. There are different types of shells, namely thick and thin shells. G. Brankov, S.N. Krivoshapko, V.N. Ivanov, and V.A. Romanova made interesting researches of shells in the form of umbrella and umbrella-type surfaces. The term nonlinear refers to a given structure undergoing a change in stiffness in its loaded state. There are basically three different types of nonlinearities: geometric, physical and contact (boundary condition nonlinearity). For further analysis of the stress-strain state, a paraboloid with an inner radius of 4 m and an outer radius of 20 m and the number of waves equal to 6 was considered. The test shell is made of reinforced concrete. The minimum load parameter at which the shell loses stability indicates a more than three times the margin.

Sign in / Sign up

Export Citation Format

Share Document