Finite-element analysis of thermal expansion and thermal mismatch stresses in a Cu–60vol%ZrW2O8 composite

2004 ◽  
Vol 64 (12) ◽  
pp. 1895-1898 ◽  
Author(s):  
S Yilmaz ◽  
D.C Dunand
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Thermal Expansion ◽  
Thermal Mismatch ◽  
Element Analysis

Linear Thermomechanical Microactuators

1999 ◽  
Author(s):  
Rebecca Cragun ◽  
Larry L. Howell
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Thermal Expansion ◽  
Cross Sections ◽  
Variable Cross ◽  
Element Analysis ◽  
Thermal Actuators ◽  
Output Force ◽  
Analysis Models ◽  
High Output

Abstract Thermomechanical in-plane microactuators (TIMs) have been designed, modeled, fabricated, and tested. TIMs offer an alternative to arrays of smaller thermal actuators to obtain high output forces. The design is easily modified to obtain the desired output force or deflection for specific applications. The operational principle is based on the symmetrical thermal expansion of variable cross sections of the surface micromachined microdevice. Sixteen configurations of TIMs were fabricated of polysilicon. Finite element analysis models were used to predict the deflection and output force for the actuators. Experimental results were also recorded for all sixteen configurations, including deflections and output forces up to 20 micron and 35 dyne.

Thermal compensation using the hybrid metrology approach compared to traditional scaling

2017 ◽  
Vol 232 (13) ◽  
pp. 2364-2374
Author(s):  
David Ross-Pinnock ◽  
Glen Mullineux
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Thermal Expansion ◽  
Temperature Measurement ◽  
Large Scale ◽  
Element Analysis ◽  
Linear Temperature ◽  
Temperature Distributions ◽  
Finite Element Analysis Simulation ◽  
Uniform Scaling

Control of temperature in large-scale manufacturing environments is not always practical or economical, introducing thermal effects including variation in ambient refractive index and thermal expansion. Thermal expansion is one of the largest contributors to measurement uncertainty; however, temperature distributions are not widely measured. Uncertainties can also be introduced in scaling to standard temperature. For more complex temperature distributions with non-linear temperature gradients, uniform scaling is unrealistic. Deformations have been measured photogrammetrically in two thermally challenging scenarios with localised heating. Extended temperature measurement has been tested with finite element analysis to assess a compensation methodology for coordinate measurement. This has been compared to commonly used uniform scaling and has outperformed this with a highly simplified finite element analysis simulation in scaling a number of coordinates at once. This work highlighted the need for focus on reproducible temperature measurement for dimensional measurement in non-standard environments.

Development of an Engineering Model for Predicting the Transverse Coefficients of Thermal Expansion of Unidirectional Fiber Reinforced Composites

2009 ◽  
Vol 131 (3) ◽  
Author(s):  
Chensong Dong
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Thermal Expansion ◽  
Fiber Reinforced Composites ◽  
Reinforced Composites ◽  
Fiber Reinforced ◽  
Engineering Model ◽  
Element Analysis ◽  
Unidirectional Composites ◽  
Representative Unit Cell

The coefficients of thermal expansion (CTEs) of fiber reinforced composites play an important role in the design and analysis of composite structures. Since the thermal expansion coefficients of polymer matrix materials are typically much higher than those of fibers, and the fiber often exhibits anisotropic thermal and mechanical properties, the stress induced in the composite due to temperature change is very complex. Large discrepancies exist among the analytical models for the transverse CTE of unidirectional composites. Hence, it is problematic when choosing a suitable model. With the development of computer technologies, finite element analysis (FEA) proved its effectiveness in calculating the effective CTE of composites. In this study, the transverse CTEs of unidirectional carbon fiber composites were calculated by finite element analysis using a representative unit cell. The analytical micromechanical models from literature were compared against the FEA data. It shows that Hashin’s concentric cylinder model is the best. However, it is inconvenient for practical applications due to the amount of computation. In this study, based on the FEA data, an engineering model for predicting the transverse CTE of unidirectional composites was developed by regression analysis. This model was validated against the FEA and experimental data. It shows that the developed model provides a simple and accurate approach to calculate the transverse CTE of unidirectional composites.

Determining track-induced lateral thermal expansion forces on a curved railway track

2021 ◽  
pp. 095440972199531
Author(s):  
Jubair A Musazay ◽  
Allan M Zarembski ◽  
Joseph W Palese
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Thermal Expansion ◽  
Stress Analysis ◽  
Railway Track ◽  
Thin Wall ◽  
Element Analysis ◽  
Thermally Induced ◽  
Wide Range ◽  
Research Studies

This research studies the development of lateral thermal expansion forces on a curved railway track. The geometric alignment of a railway right of way often requires railway tracks to be curved. This curvature which is usually defined by the radius of curvature or degree of curvature represents a higher level of complexity in the track’s analysis and design process. Particularly, presence of curvature on the track introduces multiple sources of force in the lateral (radial) direction, including, but not limited to, lateral thermal expansion, lateral wheel/rail forces due to centrifugal action, lateral components of vertical loads, bogie hunting and nosing effects of locomotives, and vehicle curving dynamics. Some of these forces are well understood such as centrifugal forces while some are not as well understood, such as lateral thermal expansion forces. To bridge this gap, this research studies the development of track-induced lateral thermal expansion forces on a curved railway track. In this research, the curved track is assumed to be an arbitrary arc section of a circular track and is modeled as an equivalent idealized circular ring for analysis. Owing to its importance, three analytical methods are used to include: 1) Timoshenko thermoelastic stress analysis in cylindrical coordinate system, 2) mechanics of thin wall cylinders and 3) adaptation of a variational calculus formulation method from a previous comparable study. A fourth analysis approach is also introduced using a commercially available finite element analysis package. The results of these analyses are compared through a wide range of parametric studies and are then validated by the finite element analysis. The results of this study showed that the several methods presented in this paper, could be used to approximate thermally induced expansion behavior (pre-buckling) on a curved railway track. While all three techniques are effective, the Timoshenko stress analysis method appears to be the most suitable as it is a direct method that examines the stress build up from the element level and takes into account additional material properties, such as the Poisson effect. The research resulted in a methodology for determining load transfer from thermally induced forces in curved railroad track to the fastener and supporting structure.

Finite-Element Modeling and Analysis of Early-Age Cracking Risk of Cast-In-Place Concrete Culverts

2018 ◽  
Vol 2672 (27) ◽  
pp. 24-36 ◽  
Author(s):  
Yalin Liu ◽  
Anton K. Schindler ◽  
James S. Davidson
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Thermal Expansion ◽  
Lightweight Concrete ◽  
Coefficient Of Thermal Expansion ◽  
Early Age ◽  
Thermal Coefficient ◽  
Element Analysis ◽  
Joint Spacing ◽  
Cracking Risk

Extensive cracking was found in several cast-in-place concrete culverts in Alabama. This condition can decrease the long-term durability of the culverts. Early-age stress development in concrete is influenced by temperature changes, modulus of elasticity, stress relaxation, shrinkage, thermal coefficient of expansion, and the degree of restraint. The objective of this study is to determine means to mitigate early-age cracking in culverts by evaluating the cracking risk. Finite-element analysis was used to model the early-age stress by accounting for the following factors: construction sequencing, support restraint, concrete constituents, temperature effects, and the time-dependent development of mechanical properties, creep/relaxation, and drying shrinkage. Experimental results from restraint to volume change tests with rigid cracking frames were used to verify the accuracy of the finite-element analysis. A parametric study was performed to quantify the effect of changing joint spacing, joint type, construction sequence, concrete coefficient of thermal expansion, placement season, and concrete type on the risk of early-age cracking. The finite-element model results revealed that the use of the following measures will reduce the risk of early-age cracking in cast-in-place concrete culverts: concrete with lower coefficient of thermal expansion, contraction joints, sand-lightweight concrete or all-lightweight concrete, and scheduling the casting of the culvert wall to minimize the difference in its placement time relative to its previously cast base. Alternatively, to minimize the contribution of thermal effects on risk of cracking, the construction schedule should be developed to avoid concrete placement during hot weather conditions.

Heat and Fluid Flow Characters of Single-Screw for Extrusion Molding by Finite Element Analysis

2008 ◽  
Vol 47-50 ◽  
pp. 1067-1070
Author(s):  
Hyo Hee Chung ◽  
Myung Seok Ko ◽  
Seung Hyun Chol ◽  
Jae Yeol Kim ◽  
Kyung Seok Song
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Thermal Expansion ◽  
Dynamic Characteristic ◽  
Element Analysis ◽  
Single Screw ◽  
Special Quality ◽  
Third Dimension ◽  
Heat And Fluid Flow

Extrusion screw that is used on market of present extrusion molding catapult is divided by single-axle extrusion screw and multi-axles extrusion screw. Simulation technique of screw that is used in extrusion molding has become so far various. Consist of that analyze third dimension model and that analyze two-dimension model but most Analysis that display dynamic characteristic of screw inside of heat and flow in detail was not until present. Transfer of polymer site that typical single-axle extrusion screw that is analysis target of this treatise is mixed in most melting state is good, but has some controversial points. First melting transfer of balance that is not done difficult. Second melting causes effect that weaken mechanical special quality of screw by power excessive last month if heighten the screw speed to increase amount of done balance. Third Screw dynamic characteristic symptoms by thermal expansion that happen in screw of heater is fallen.

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