Relevant bibliographies by topics / Constrained thermal expansion

Academic literature on the topic 'Constrained thermal expansion'

Author: Grafiati
Published: 10 December 2022
Last updated: 28 January 2023

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles

Select a source type:

Contents

Consult the lists of relevant articles, books, theses, conference reports, and other scholarly sources on the topic 'Constrained thermal expansion.'

Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.

You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.

Journal articles on the topic "Constrained thermal expansion"

1

Ho, S., and Z. Suo. "Tunneling Cracks in Constrained Layers." Journal of Applied Mechanics 60, no. 4 (December 1, 1993): 890–94. http://dx.doi.org/10.1115/1.2900998.

Full text
Abstract:
A thin, brittle layer bonded between tougher substrates is susceptible to cracking under residual and applied stresses. Such a crack initiates from an equi-axed flaw, confined by the substrates, tunneling in the brittle layer. Although tunneling is a three-dimensional process, the energy release rate at the front of a steady-state tunnel can be computed using plane strain fields. Several technically important problems are analyzed, including tunnels in adhesive joints, shear fracture, and kinked tunnels in a reaction product layer. The concept is finally applied to microcracking in brittle matrix composites caused by thermal expansion mismatch.
APA, Harvard, Vancouver, ISO, and other styles
2

Sahu, Chinmay, V. Kirubakaran, TK Radhakrishnan, and N. Sivakumaran. "Explicit model predictive control of split-type air conditioning system." Transactions of the Institute of Measurement and Control 39, no. 5 (December 16, 2015): 754–62. http://dx.doi.org/10.1177/0142331215619976.

Full text
Abstract:
Domestic air conditioners are a major source of energy consumption. In this study, utilizing real-time data from a public domain, a cascaded hardware in loop approach to the control of room temperature is considered. An inner loop to control the supply air temperature by adjusting the electronic expansion valve using a second-order plus delay time model is proposed. The room temperature control is considered the outer loop. A simplified lumped parameter representation of the thermal dynamics of the building is modelled in MATLAB using ordinary differential equations. A constrained multi parametric model predictive controller (mpMPC) is designed for both the control loops. The constraints include safety limits on the superheat and manipulation rates for the inner loop and a rate constraint on the reference signal in the outer loop. Model uncertainties like ambient temperature and thermal load variations (representing an office space) are considered for hardware in the loop testing of the proposed strategy. From performance analysis, using power spent and thermal comfort quantization, it is observed that the mpMPC scheme outperforms traditional control strategies.
APA, Harvard, Vancouver, ISO, and other styles
3

Wang, Lucai, Yanli Wang, Xiaohong You, and Fang Wang. "Foaming Behavior and Pore Structure Evolution of Foamed Aluminum under the Extrusion Constraint." Advances in Materials Science and Engineering 2020 (December 22, 2020): 1–10. http://dx.doi.org/10.1155/2020/3948378.

Full text
Abstract:
This study evaluates foaming behavior and pore structure evolution of aluminum foam by cross-sectional image processing, which was prepared by the powder compact melting (PCM) method under the constraint. The results revealed that the heating time and the heating rate are the key factors affecting the foaming behavior and pore structure of aluminum foam. The thermal decomposition of the foaming agent and aluminum melting behavior affect the foam expansion under different heating times and heating rates. The evolution of the pore structure during the foaming process includes pore formation, small-sized spherical pores, large-sized spherical pores, polygonal pores, merging, and collapse. Due to the limitation of the pipe wall, the maximum expansion height and porosity are constrained, and the macrostructure of aluminum foam is improved.
APA, Harvard, Vancouver, ISO, and other styles
4

Wendt, David, Emil Bozin, Joerg Neuefeind, Katharine Page, Wei Ku, Limin Wang, Brent Fultz, Alexei V. Tkachenko, and Igor A. Zaliznyak. "Entropic elasticity and negative thermal expansion in a simple cubic crystal." Science Advances 5, no. 11 (November 2019): eaay2748. http://dx.doi.org/10.1126/sciadv.aay2748.

Full text
Abstract:
While most solids expand when heated, some materials show the opposite behavior: negative thermal expansion (NTE). In polymers and biomolecules, NTE originates from the entropic elasticity of an ideal, freely jointed chain. The origin of NTE in solids has been widely believed to be different. Our neutron scattering study of a simple cubic NTE material, ScF3, overturns this consensus. We observe that the correlation in the positions of the neighboring fluorine atoms rapidly fades on warming, indicating an uncorrelated thermal motion constrained by the rigid Sc-F bonds. This leads us to a quantitative theory of NTE in terms of entropic elasticity of a floppy network crystal, which is in remarkable agreement with experimental results. We thus reveal the formidable universality of the NTE phenomenon in soft and hard matter.
APA, Harvard, Vancouver, ISO, and other styles
5

Nowok, J. W., J. P. Kay, and R. J. Kulas. "Thermal expansion and high-temperature phase transformation of the yttrium silicate Y2SiO5." Journal of Materials Research 16, no. 8 (August 2001): 2251–55. http://dx.doi.org/10.1557/jmr.2001.0309.

Full text
Abstract:
The linear thermal-expansion coefficients of yttrium silicate Y2SiO5, [Y2(SiO4)O] were measured in the temperature range from 20 to 1400 °C using x-ray diffraction. The anomalous behavior of thermal expansion was observed above Tc = 850 °C and was attributed to the displacive phase transformation. The transformation was reversible and resulted from the local order °C the compositional disorder and local fluctuation in the elastic free energy constrained a secondary transformation related to the polymorphic twin transformation. This created an additional peak in x-ray diffraction patterns at 2 's intensity. The characteristic of phase transformation both on heating and on cooling of the sample was also investigated using the differential thermal analysis method. The thermogravimetric technique did not indicate on a change of weight at Tc.
APA, Harvard, Vancouver, ISO, and other styles
6

Li, Hui Fang, Cai Fu Qian, and Xiao Dong Yu. "Thermal Stress Analysis of a Tubesheet with a Welding Clad." Advanced Materials Research 201-203 (February 2011): 302–7. http://dx.doi.org/10.4028/www.scientific.net/amr.201-203.302.

Full text
Abstract:
In this paper, numerical simulation was carried out for the tube bundle of a slurry oil steam generator with concentration on the thermal stresses at the tubesheet with or without a welding clad on the tubesheet surface. It is found that as having a larger heat expansion coefficient, thermal expansion of the welding clad is constrained and most areas are in compressive state. But the tensile stresses in the clad are also notable especially at the interface and could break the clad if added by the tensile stresses produced by pressure loadings. Presence of the welding clad causes significant tensile stresses in the base tubesheet. It is possible that the maximum tensile stress comprised by the thermal tensile stress and pressure induced tensile stress will exceed the tensile strength of the material and cause initiation of cracks in the tubesheet.
APA, Harvard, Vancouver, ISO, and other styles
7

Solanki, Prem K., and Yoed Rabin. "Perspective: Temperature-Dependent Density And Thermal Expansion Of Cryoprotective Agents." Cryoletters 43, no. 1 (January 1, 2022): 1–9. http://dx.doi.org/10.54680/fr22110110112.

Full text
Abstract:
Density is a key thermophysical property, affecting the response of materials to temperature changes in different ways, consistent with the phase of state. In fluids, temperature variation across the domain leads to colder areas being heavier than warmer areas, where buoyancy effects drive fluid flow and thereby increase heat transfer. This phenomenon is known as natural heat convection, which in general is a more efficient heat transfer mechanism than heat conduction in the absence of flow. In solids, where the material is locked in place, colder areas tend to contract while warmer areas tend to expand, leading the material to deform. When this deformation is constrained by the geometry of the domain and/or its container, mechanical stresses develop. This phenomenon is known as thermomechanical stress (or thermal stress), which can lead to structural damage such as fractures. The picture becomes even more complex during vitrification (or glass formation), where the material gradually changes from liquid to an amorphous solid over a significant temperature range. There, due to temperature variation across the domain, fluid mechanics and solid mechanics effects may coexist. It follows that characterization of the density as a function of temperature is crucial for the analyses of thermal, fluid, and mechanical effects during cryopreservation, with the goals of protocol planning, optimization, and preserving structural integrity. For this purpose, the current study focuses on the density of the material and its companion property of thermal expansion. Specifically, this paper reviews literature data on thermal expansion of cryoprotective agents (CPAs), discusses the mathematical relationship between thermal expansion and density, and presents new calculated density data. This study focuses on the CPA cocktails DP6, VS55, M22, and their key ingredients at various concentrations, including DMSO, propylene glycol, and formamide. Data for DP6 combined with a selection of synthetic ice modulators (SIMs) are further presented.
APA, Harvard, Vancouver, ISO, and other styles
8

REPETTO, CARLOS E., and OSCAR P. ZANDRON. "PERTURBATIVE EXPANSION FOR THE t-J MODEL CONSTRUCTED FROM THE GENERATORS OF THE SUPERSYMMETRIC HUBBARD ALGEBRA." International Journal of Modern Physics B 23, no. 14 (June 10, 2009): 3159–77. http://dx.doi.org/10.1142/s0217979209052856.

Full text
Abstract:
By using the Hubbard [Formula: see text]-operators as field variables along with the supersymmetric version of the Faddeev–Jackiw symplectic formalism, a family of first-order constrained Lagrangians for the t-J model is found. In order to satisfy the Hubbard [Formula: see text]-operator commutation rules satisfying the graded algebra spl(2,1), the number and kind of constraints that must be included in a classical first-order Lagrangian formalism for this model are presented. The model is also analyzed via path-integral formalism, where the correlation-generating functional and the effective Lagrangian are constructed. In this context, the introduction of a proper ghost field is needed to render the model renormalizable. The perturbative Lagrangian formalism is developed and it is shown how propagators and vertices can be renormalized to each order. In particular, the renormalized ferromagnetic magnon propagator arising in the present formalism is discussed. As an example, the thermal softening of the magnon frequency is computed.
APA, Harvard, Vancouver, ISO, and other styles
9

Rajak, Neeraj K., Neha Kondedan, Husna Jan, Muhammed Dilshah U, S. D. Navya, Aswathy Kaipamangalath, Manoj Ramavarma, Chandrahas Bansal, and Deepshikha Jaiswal-Nagar. "Setup of high resolution thermal expansion measurements in closed cycle cryostats using capacitive dilatometers." Journal of Physics Communications 5, no. 12 (December 1, 2021): 125004. http://dx.doi.org/10.1088/2399-6528/ac3a44.

Full text
Abstract:
Abstract We present high resolution thermal expansion measurement data obtained with high relative sensitivity of ΔL/L = 10−9 and accuracy of ± 2 % using closed cycle refrigerators employing two different dilatometers. Experimental details of the set-up utilizing the multi-function probe integrated with the cold head of two kinds of closed cycle refrigerators, namely, pulse tube and Gifford-McMahon cryocoolers, has been described in detail. The design consists of decoupling the bottom sample puck and taking connections from the top of the multi-function probe to mitigate the vibrational noise arising from the cold heads, using which smooth and high quality thermal expansion data could be obtained. It was found that dilatometer#2 performs a better noise mitigation than dilatometer#1 due to the constrained movement of the spring in dilatometer#2. This was confirmed by finite element method simulations that were performed for understanding the spring movement in each dilatometer using which the effect of different forces/pressures and vibrations on the displacement of the spring was studied. Linear thermal expansion coefficient α obtained using both dilatometers was evaluated using derivative of a polynomial fit. The resultant α obtained using dilatometer#2 and either of the closed cycle cryostats on standard metals silver and aluminium showed excellent match with published values obtained using wet cryostats. Finally, thermal expansion measurements is reported on single crystals of two high temperature superconductors YBa2Cu3−x Al x O6+δ and Bi2Sr2CaCu2O8+x along the c-axis with very good match found with published data obtained earlier using wet liquid helium based cryostats.
APA, Harvard, Vancouver, ISO, and other styles
10

Staroszczyk, Ryszard. "On maximum forces exerted by floating ice on a structure due to constrained thermal expansion of ice." Marine Structures 75 (January 2021): 102884. http://dx.doi.org/10.1016/j.marstruc.2020.102884.

Full text
APA, Harvard, Vancouver, ISO, and other styles
More sources

Book chapters on the topic "Constrained thermal expansion"

1

Martin, Katharina, Dennis Daub, Burkard Esser, Ali Gülhan, and Stefanie Reese. "Numerical Modelling of Fluid-Structure Interaction for Thermal Buckling in Hypersonic Flow." In Notes on Numerical Fluid Mechanics and Multidisciplinary Design, 341–55. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-53847-7_22.

Full text
Abstract:
Abstract Experiments have shown that a high-enthalpy flow field might lead under certain mechanical constraints to buckling effects and plastic deformation. The panel buckling into the flow changes the flow field causing locally increased heating which in turn affects the panel deformation. The temperature increase due to aerothermal heating in the hypersonic flow causes the metallic panel to buckle into the flow. To investigate these phenomena numerically, a thermomechanical simulation of a fluid-structure interaction (FSI) model for thermal buckling is presented. The FSI simulation is set up in a staggered scheme and split into a thermal solid, a mechanical solid and a fluid computation. The structural solver Abaqus and the fluid solver TAU from the German Aerospace Center (DLR) are coupled within the FSI code ifls developed at the Institute of Aircraft Design and Lightweight Structures (IFL) at TU Braunschweig. The FSI setup focuses on the choice of an equilibrium iteration method, the time integration and the data transfer between grids. To model the complex material behaviour of the structure, a viscoplastic material model with linear isotropic hardening and thermal expansion including material parameters, which are nonlinearly dependent on temperature, is used.
APA, Harvard, Vancouver, ISO, and other styles
2

Singh, Sudarshan, and Warangkana Chunglok. "Thermo-Mechanical Properties of Bio-Based Polymers." In Biopolymers Towards Green and Sustainable Development, 90–104. BENTHAM SCIENCE PUBLISHERS, 2022. http://dx.doi.org/10.2174/9789815079302122010007.

Full text
Abstract:
Bio-based polymers offer a broad range of applications in pharmaceutical engineering. However, their assortment gets constrained owing to variations in structural conformation, which affects the thermomechanical properties during complex formulation. The thermomechanical property of pharmaceutically inactive ingredients provides insight into the thermal expansion, glass transitions temperature, softening point, compositional, and phase changes of biomaterials with different geometries on the application of constant force as a function of temperature. In addition, thermomechanical properties provide fundamental information on network chemical structure, crosslink density, rubbery modulus, failure strain, and toughness. Moreover, the structural composition of polysaccharides also affects the composite’s mechanical properties. Hence, analysis of thermomechanical properties provides valuable information that is applicable in different sectors including aviation, quasistatic loading, electroplating technology, micro-electric, construction, cosmetics, food packaging, and pharmaceutical products. This compilation highlights the basics of thermal and mechanical experiments on bio-based polymers with different fabrication for both technical and pharmaceutical formulations.
APA, Harvard, Vancouver, ISO, and other styles
3

Pekguleryuz, Mihriban, Erol Ozbakir, and Amir Rezaei Farkoosh. "Diesel Engine: Applications of Aluminum Alloys." In Encyclopedia of Aluminum and Its Alloys. Boca Raton: CRC Press, 2019. http://dx.doi.org/10.1201/9781351045636-140000329.

Full text
Abstract:
The Diesel engine, introduced by Rudolph Diesel in 1892, achieves a higher combustion ratio and fuel efficiency, has lower CO2 emissions per mile than the gasoline engine and is considered to be one of the most viable environmentally friendly technologies for vehicles. “Clean Diesel” using lower sulfur content fuel has become available since 2006. Currently, the Diesel engine and cylinder head are mostly cast iron to withstand the high compression pressures and temperatures of Diesel operation. Further weight reduction (40%–55%) via aluminum substitution in the Diesel engine would result in substantial fuel economy and increased environmental benefits. Current aluminum alloys cannot meet the requirements of the Diesel engine and a new research topic has emerged in aluminum materials technology to address these requirements. The main issue with aluminum alloys is the low resistance to thermal fatigue that results from the constrained expansion and contraction of the material in the interval regions leading to compressive creep deformation at 300°C during engine heat-up and to tensile deformation around 150°C during engine cooldown. This article discusses the performance requirements and the design principles for aluminum alloys for Diesel engine applications. Efforts on the modification of A356 and A319 alloys via Cu, Mg, Ni, Cr, V, Zr, Ti, and Mn addition are reviewed. Recent studies on Mn/Mo addition are presented and the related principles are introduced in designing high volume fraction, thermally stable, and uniform nanoscale dispersoids using solutes with opposite partitioning coefficients in aluminum.
APA, Harvard, Vancouver, ISO, and other styles
4

Song, Xinfu, Chaoshan Xin, Jin Yu, Zhiyong Yu, Danhua Shen, and Junliang Ma. "A New Energy Power Grid Expansion Planning Technology Considering Optimal Economy." In Advances in Transdisciplinary Engineering. IOS Press, 2022. http://dx.doi.org/10.3233/atde220260.

Full text
Abstract:
This paper examines the path of new energy development in China against the backdrop of carbon maximum and carbon neutralization, and studies the risk of large scale new energy power transmission. In order to solve the complex uncertainty challenges of renewables power and power grid expansion planning, this paper studies and proposes an optimal economic planning model, which includes the thermal power generation start-up and shutdown expenses during the operation, the hydro power generation expenses of surplus water of reservoir, and the curtail penalty cost of new energy output power, the investment of new planning lines. The model has also considered the constraints of balance for power generation and load consumption, the power change rate, and operation, which are calculated based on the time-series operation simulation of new energy power system. Based on the functions, the process of power grid planning technology has been proposed. The planning model proposed in this paper can consider the new energy power characteristics of generation, realize the optimal planning of different power grid schemes. According to the case study findings, the new transmission line can relieve the pressure of local new energy transmission, while also improving power flow distribution as well as the rate of new energy utilization.
APA, Harvard, Vancouver, ISO, and other styles

Conference papers on the topic "Constrained thermal expansion"

1

Rooney, Francis J., and Stephen E. Bechtel. "Modeling of Thermal Expansion." In ASME 1999 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1999. http://dx.doi.org/10.1115/imece1999-0937.

Full text
Abstract:
Abstract In this paper we treat two types of thermomechanical constraints, temperature-deformation and entropy-deformation. It is shown that for the temperature-deformation constraint equilibrium states are unstable, in that certain perturbations of the equilibrium state grow exponentially. The entropy-deformation constraint, however, does not exhibit this instability. By considering the constrained materials as limits of unconstrained materials, it is shown that the instability is associated with the loss of convexity of the internal energy.
APA, Harvard, Vancouver, ISO, and other styles
2

Cragun, Rebecca, and Larry L. Howell. "A Constrained Thermal Expansion Micro-Actuator." In ASME 1998 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1998. http://dx.doi.org/10.1115/imece1998-1270.

Full text
Abstract:
Abstract This paper describes a series of thermal micro-actuators fabricated from polycrystalline silicon. These actuators use geometric constraints to amplify motion from thermal expansion. Compliant mechanism theory, particularly the pseudo-rigid-body model, was used to aid in the visualization of the device’s behavior. Nonlinear finite element analysis was used to analyze the actuators and refine the designs. The resulting mechanisms were fabricated and tested. Maximum deflections of over 20 μm were obtained with a total cycle time faster than 4 milliseconds. A bi-directional actuator capable of 6 μm displacements in both directions is also described.
APA, Harvard, Vancouver, ISO, and other styles
3

Nucera, Claudio, and Francesco Lanza di Scalea. "Nonlinear guided waves in solids under constrained thermal expansion." In SPIE Smart Structures and Materials + Nondestructive Evaluation and Health Monitoring, edited by Tribikram Kundu. SPIE, 2013. http://dx.doi.org/10.1117/12.2009793.

Full text
APA, Harvard, Vancouver, ISO, and other styles
4

Nucera, Claudio, and Francesco Lanza di Scalea. "Nonlinearity in Ultrasonic Guided Waves Propagation in Solids Under Constrained Thermal Expansion." In ASME 2013 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/imece2013-63755.

Full text
Abstract:
Finite strain theory has been employed in the past to mathematically describe nonlinear wave propagation phenomena such as acoustoelasticity (wave speed dependency on quasi-static stress), wave interaction, wave distortion, and higher-harmonic generation. The present work expands the topic of nonlinear wave propagation to the case of a constrained solid subjected to thermal loads. In this framework, the anharmonicity of interatomic potentials, and the absorption of the potential energy corresponding to the (prevented) thermal expansion, are identified as sources of nonlinear effects. Such “residual” energy is, at least, cubic as a function of strain, hence leading to a nonlinear wave equation and higher-harmonic generation. Closed-form solutions are given for the longitudinal wave speed and the second-harmonic nonlinear parameter as a function of interatomic potential parameters and temperature increase. According to the proposed model, the prevented thermal expansion of the solid leads to thermal stresses that, in turn, produce a decrease in longitudinal wave speed and a corresponding increase in nonlinear parameter with increasing temperature. Experimental measurements of the ultrasonic nonlinear parameter on a steel block under constrained thermal expansion confirm this trend. Emphasis is placed on the potential of a nonlinear ultrasonic measurement to quantify thermal stresses from prevented thermal expansion. This knowledge can be extremely useful to prevent thermal buckling of various structures, such as continuous-welded rails in hot weather.
APA, Harvard, Vancouver, ISO, and other styles
5

Thompson, Ben, Dragana Simon, Murray Grabinsky, David Counter, and William Bawden. "Constrained thermal expansion as a causal mechanism for in situ pressure in cemented paste and hydraulic backfilled stopes." In Eleventh International Symposium on Mining with Backfill. Australian Centre for Geomechanics, Perth, 2014. http://dx.doi.org/10.36487/acg_rep/1404_29_thompson.

Full text
APA, Harvard, Vancouver, ISO, and other styles
6

Marohl, Michael P. H., Glenn R. Frazee, and Thomas M. Musto. "Relative Influence of Soil Stiffness and Elbow Geometry on Buried Piping Thermal Stresses." In ASME 2017 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/pvp2017-65591.

Full text
Abstract:
The design of buried piping systems requires special considerations. Historically, buried piping was evaluated for thermal expansion and contraction using simple hand calculations considering the piping to be fully-constrained by the surrounding soil. With the development of analytical software, more advanced analysis of buried piping is possible considering detailed piping routing and the stiffness of the surrounding soil and of the piping itself (in cases of more flexible piping materials). Typically, the areas of highest thermal stress occur at changes in direction (i.e. elbows, etc.) due to the applied moments, and the relative stress magnitude is influenced by the stiffness of the surrounding soil. Due to the relatively high coefficient of thermal expansion of polyethylene, stresses in buried piping due to thermal expansion and contraction are of particular note for high density polyethylene (HDPE) piping. This paper examines the relative influence of the analytical representations of a variety of HDPE piping elbow geometries (e.g. mitered elbows, molded elbows, etc.) and corresponding soil restraint. The study demonstrates that total longitudinal stress calculated in a finite element analysis may be reduced using minor to moderate efforts of refinement.
APA, Harvard, Vancouver, ISO, and other styles
7

Li, Guang-Rong, Juan Lei, Guan-Jun Yang, Cheng-Xin Li, and Chang-Jiu Li. "Constrained Healing and Morphology Change Mechanism of 2D Cracks in Plasma Sprayed Thermal Barrier Coatings." In ITSC2015, edited by A. Agarwal, G. Bolelli, A. Concustell, Y. C. Lau, A. McDonald, F. L. Toma, E. Turunen, and C. A. Widener. ASM International, 2015. http://dx.doi.org/10.31399/asm.cp.itsc2015p0258.

Full text
Abstract:
Abstract The stiffness and thermal conductivity of thermal barrier coatings (TBCs) are inevitably changed by healing up of intersplat pores and intra-splat cracks during high temperature exposure, which results in less compliance and thermal insulating performance. However most publications on sintering of plasma sprayed TBCs are based on free-standing coatings, which ignore residual stress and the stress produced by the mismatch of thermal expansion coefficient between substrate and ceramic top coatings. In this paper, individual splat of YSZ and YSZ coatings have been sprayed on substrate of YSZ and Ni-based superalloy. Evolution of healing and morphology of 2D cracks and some properties, such as hardness and thermal conductivity, have been revealed during thermal exposure. Results showed that, during heating stage, the shear stress coming from substrate caused some tearing of bonding area tips and narrowing of inter-splat pores. Some recoverable and unrecoverable widening on intra-splat cracks occurred also due to shear stress. During annealing stage, compared with free-standing coating, the surface hardness of the coating deposited onto the Ni-based superalloy showed enhanced increasing due to the faster healing of inter-splat pores by narrowing down, and the hardness in cross-section presented retarding increasing due to the widening of cracks in out-plane direction leading to slower healing. The case of YSZ substrate fell between free-standing case and Ni-based superalloy. This would benefit the further in-depth understanding of the thermal cycling failure mechanism of plasma sprayed TBCs.
APA, Harvard, Vancouver, ISO, and other styles
8

Li, Jun, and G. K. Ananthasuresh. "Microfabrication and Characterization of Electro-Thermal-Compliant Micro Devices." In ASME 2000 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2000. http://dx.doi.org/10.1115/detc2000/mech-14118.

Full text
Abstract:
Abstract Electro-Thermal-Compliant (ETC) micro devices are a new class of compliant mechanisms that elastically deform in response to Joule-heating induced constrained thermal expansion. In ETC devices, the mechanism and the actuator are indistinguishable and therefore it is called embedded actuation. This type of actuation is attractive for Micro-Electro-Mechanical Systems (MEMS) where the actuator is often much larger than the mechanism and the mechanical coupling of the actuator and mechanism leads to additional difficulties. In this paper, we focus on thin, planar, appropriately shaped, deformable structures made of a conducting material to fabricate micro mechanisms with embedded actuation. We have developed a bulk micromachining process, called PennSOIL, using silicon-on-insulator (SOI) wafers to make silicon ETC devices, and also combined PennSOIL with excimer laser micromachining to make ETC devices with not only silicon but also a variety of metals. The experimental measurements are compared with the theoretical predictions. Test-structures are used to characterize the process and the resulting materials properties some of which are strongly temperature-dependent and process-dependent. The experimental results using the materials properties obtained from the test structures show agreement with the theoretical results.
APA, Harvard, Vancouver, ISO, and other styles
9

Zhu, Zi-Qin, Li-Wu Fan, Min-Jie Liu, and Yi Zeng. "Heat Transfer During Constrained Melting of Graphite-Based Nanofluids in a Spherical Capsule." In ASME 2016 5th International Conference on Micro/Nanoscale Heat and Mass Transfer. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/mnhmt2016-6316.

Full text
Abstract:
Transient heat transfer during constrained melting of graphite-based solid-liquid phase change nanofluids in a spherical capsule was investigated experimentally. Nanofluids filled with self-prepared graphite nanosheets (GNSs) were prepared at various loadings up to 1% by weight, using a straight-chain saturated fatty alcohol, i.e., 1-dodecanol (C12H26O), with a nominal melting point of 22 °C as the base fluid. In-house measured thermal properties were adopted for data reduction, including thermal conductivity, dynamic viscosity, latent heat of fusion, specific heat capacity and density. A proper experimental approach depended on volume expansion was figured out to monitor the melting process of nano-enhanced phase change fluid in a spherical capsule indirectly and qualitatively characterize the process. A variety of boundary temperatures were also adopted to vary the intensity of natural convection. It was shown that under low boundary temperatures, a monotonous melting acceleration came into being while increasing the loading due to the monotonously increased thermal conductivity of the nanofluids. While increasing the boundary temperature leads to more intensive natural convection that in turn slowed down melting under the influence of nanoparticles because the contribution by natural convection is significantly suppressed by the dramatically grown dynamic viscosity, e.g., more than 60-fold increase at the loading of 1 wt.%. The melting rate is determined by the competition between the enhanced heat conduction and deteriorated natural convection.
APA, Harvard, Vancouver, ISO, and other styles
10

Hsu, S. M., J. C. Lin, and K. N. Chiang. "A Full-Scale 3D Finite Element Analysis for No-Underfill Flip Chip Package." In ASME 2002 International Mechanical Engineering Congress and Exposition. ASMEDC, 2002. http://dx.doi.org/10.1115/imece2002-39674.

Full text
Abstract:
This research establishes a micro-macro 3D finite element model for no underfill flip chip BGA package. The no underfill package uses a ceramic-like (CTE close to silicon) material mounted on the backside of the flip chip substrate to constrain the thermal expansion of the organic substrate and enhance the reliability of the solder joint. This work attempts to design a constrained structure to enhance the reliability of the no underfill flip chip package. For the special design of constrained structure, a full-scale 3D finite element model is needed to investigate some mechanical behaviors that cannot be revealed by the 2D finite element model. However, to establish a full-scale 3D finite element model, the large computation time is an issue. The equivalent beam concept is adopted in this research to overcome this drawback of the finite element models. The results indicate that the equivalent beam concept is a feasible methodology for reducing the computation time of the 3D finite element model. Further, the new design structure could improve package reliability, increase manufacturing throughput and thermal performance, and maintain reworkability of the flip chip structure.
APA, Harvard, Vancouver, ISO, and other styles
You might also be interested in the extended bibliographies on the topic 'Constrained thermal expansion' for particular source types:
Journal articles
We offer discounts on all premium plans for authors whose works are included in thematic literature selections. Contact us to get a unique promo code!

To the bibliography