Rapid Surface Heating Research Articles

Nonlinear vibrations of temperature-dependent FGM cylindrical panels subjected to instantaneous surface heating

An analysis is performed in this research to deal with the large amplitude vibrations caused by rapid surface heating in an FGM cylindrical panel. It is assumed that the properties of the panel are distributed through the thickness in terms of volume fraction of constituents. Following the first-order shear deformation theory, von Karman type of kinematics, and Donnell kinematic assumptions, definition of kinetic and strain energies of the shell are established. These obtained equations are discretized via the method of Ritz, where the shape functions are estimated by the Chebyshev polynomials. Temperature distribution within the body is also obtained using the one-dimensional heat conduction equation. This equation is discretized using the finite different method and solved iteratively following the Picard and Crank-Nicolson methods. Thermally induced force and moment resultants are evaluated and inserted into the matrix representation of equations of motion. The temporal evolution of displacement is obtained using the iterative Picard method and Newmark time marching method. Results of this study are compared with the available data in the open literature and after that novel results are given to explore the effects of geometrical, mechanical, and thermal parameters. It is highlighted that power law index, shallowness, thickness, edge supports, temperature dependency, geometrical nonlinearity and thermal boundary conditions are all important factors on the response of the structure under thermal shock. It is highlighted that thermally induced vibrations indeed exists especially in thin class of shells. Besides, thermally induced deflections may be controlled through using a proper power law index.

Vibrations of skew cylindrical shells made of FG-GPLRCs under rapid surface heating

An analysis is performed in this research to examine the thermally induced vibrations in skew cylindrical shells. It is assumed that shell is made from a composite laminated material where each layer is reinforced with graphene platelets (GPLs). The amount of GPLs in the layers may be different which results in a piecewise functionally graded media. The one-dimensional transient heat conduction equation is established through the thickness of the shell. Heat conduction equation is solved using the finite difference method for each layer and continuity of temperature and heat flux is applied between the layers. Crank Nicolson algorithm is implemented to obtain the temperature profile at each time step and after that thermally induced force and moment are evaluated. The kinematics of the shell are estimated following the first order shear deformation shell theory. Also it should be noted that an oblique coordinates system in addition to orthogonal system is defined which make it easier to apply the boundary conditions. The definition of strain and kinetic energies are constructed and Following the Ritz method whose shape functions are estimated by Chebyshev polynomials, energies are provided in discrete form of the governing equations. Results of this study are provided to explore the effects of thermal and mechanical boundary conditions, geometry of the shell, weight fraction and distribution patterns of GPLs. It is highlighted that thermally induced vibrations indeed exist especially in thin class of shells.

Durability and performance of wood flour/polyethylene composites containing fire retardants after weathering via ASTM D2565

Wood–plastic composites are composite materials consisting of wood particles, thermoplastic polymer, and small amounts of other performance additives to increase performance in exterior construction applications such as decking and siding. Three best-performing fire retardants, determined from a previous study, which were brominated, magnesium hydroxide, and ammonium polyphosphate, were selected for this weathering study and more detailed analysis with color analysis, thermogravimetric analysis/differential scanning calorimetry, and the cone calorimeter. With the rapid surface heating condition at cone calorimeter irradiance of 50 kW m−2, modest surface leaching of fire retardant was detected as caused by weathering via increased first peak heat-release rate and reduced time to ignition values. Otherwise, the weathering had minimal effect on the remaining heat-release rate profile, and results confirmed ammonium polyphosphate as top performing fire retardant, even better than Ipe wood, with magnesium hydroxide and brominated slightly worse than Ipe. This suggests that 35% high-density polyethylene content reduced fire retardant bulk leaching.

Stability Analysis of the Rapid Heating Multilayer Structure Mold by the Contact Error and Thickness of Layers

Rapid heating of the mold surface is necessary for the high-gloss, high-productivity injection molding process. A rapid heating mold system that uses a carbon nanotube (CNT) as a heating element was investigated because of its structure. For CNT web film to be utilized in the injection molding process, heating must be applied inside the mold. That can cause poor contact at the contact area between the mold and the CNT heating element, leading to local temperature deviation and resistance changes that reduce the heating stability of the CNT surface element. Additionally, the multilayer structure of the CNT web film can cause heat-transfer performance variations due to the different layer thicknesses. To address these issues, an adjustable flush was constructed at the contact area between the electrode inside the mold and the insulator to analyze the heating behavior of the CNT heating element as a function of dimensional deviation. The thermal durability of the CNT web film was also evaluated by analyzing the Raman spectra and measuring resistance changes caused by local overheating. The film can withstand high temperatures, with a flush limit value of 0.3 mm. An optimization analysis was conducted to determine the ideal thicknesses of the multilayer CNT web film, insulator, and electrical insulator. Optimal layer thicknesses were found to be 10 μm, 5 mm, and 0.5 mm, respectively. The main variables of the rapid heating mold required for application to the injection process were identified and reflected in the mold design to suggest directions for commercialization.

Active control of thermally induced vibrations of temperature-dependent FGM circular plate with piezoelectric sensor/actuator layers

This study investigates the novel application of active control methods in mitigating thermally induced vibrations of functionally graded material (FGM) circular plates subjected to thermal shock. The top surface of the FGM circular plate is exposed to rapid surface heating, resulting in thermally induced vibrations. To counteract these deflections, two piezoelectric layers, one functioning as a sensor and the other as an actuator, are strategically integrated into the plate opposite sides. This layered configuration effectively distances the direct rapid surface heating from piezoelectric layers. All thermos-electro-mechanical properties of the used materials are considered temperature-dependent. The research employs the Generalized differential quadrature element (GDQE) method and the Crank-Nicolson time marching procedure to solve the nonlinear Fourier-type heat conduction equations for the layered structure. After obtaining the transient temperature profile, the study calculates thermal moments, forces, and pyroelectric terms. These thermally induced effects are then integrated into the motion and electrostatic equations, which inherently exhibit nonlinearity due to the von Kármán large deformations theory. The plate displacements are approximated using the first-order shear deformation theory (FSDT) along the plate thickness, while a quadrature distribution is considered for approximating the electric potential within the piezoelectric layers. The highly coupled electro-mechanical equations are solved using the GDQ method and the Newmark approach, with the Newton-Raphson iterative scheme utilized to address nonlinearity. A significant contribution of this research lies in the exploration of three distinct active control strategies: proportional control, derivative control, and proportional-derivative control. The study thoroughly analyzes the impact of each control type on the plate response, considering various boundary conditions.

Geometrically nonlinear rapid surface heating in FGM hermetic capsule

Geometrically nonlinear rapid surface heating in FGM hermetic capsule

Tribological Performance of Laser Shock Peened Cold Spray Additive Manufactured 316L Stainless Steel

Abstract In recent years, cold spray additive manufacturing (CSAM) has become an attractive technology for surface modification and protection. However, due to the intrinsic porous nature of CSAM coatings, they suffer from rapid material degradation due to premature brittle fracturing induced by tribological interactions. In this work, laser shock peening (LSP) was utilized as a post-processing technology to mitigate the surface porosity and augment the surface characteristics of CSAM 316L stainless steel (SS). Due to the synergistic influence of severe plastic deformation and rapid surface heating, the surface porosities were effectively healed, thus reducing the surface roughness. Combined with the surface-strengthening effects of LSP, the frictional resistance and transfer layer formation on the CSAM LSP surfaces were reduced. The underlying mechanisms for these findings were discussed by correlating the atomic, microstructural, and physical features of the LSP surfaces. Based on these findings, it can be suggested that LSP is indeed a useful technique to control the surface characteristics of CSAM 316L SS coatings.

Application of GDQ method to large amplitude response of FGM joined spherical-conical shells under rapid surface heating

Geometrically non-linear thermally induced vibrations of functionally graded material (FGM) joined spherical-conical shells are analyzed in the current research. Thermo-mechanical properties of the shells are assumed to be temperature and position dependent. The system of joined spherical-conical shells is subjected to thermal shock on the ceramic-rich surface, whereas the metal-rich one is kept at reference temperature. The one-dimensional transient heat conduction equation is established and solved via the generalized differential quadrature (GDQ) and Crank-Nicolson methods. This equation is non-linear since the thermo-mechanical properties of the shells are temperature dependent. The total functional of the shells is obtained under the assumptions of uncoupled thermoelasticity laws, first order shear deformation shell theory, and the von Kármán type of geometrical non-linearity. Non-linear coupled equations of motion are solved via the iterative Picard method accompanied with the β-Newmark time approximation technique. Numerical results are well-validated with the available data for the case of single FGM spherical shell. Parametric studies are conducted to examine the influences of conical and spherical shell geometries, material composition, temperature dependence, in-plane and out-of-plane mechanical boundary conditions, various configuration of conical/spherical shell system, and thermal boundary conditions. It is highlighted that thermally induced vibrations indeed exists.

Nonlinear dynamic snap-through and vibrations of temperature-dependent FGM deep spherical shells under sudden thermal shock

In This article, nonlinear thermally induced vibrations of temperature-dependent functionally graded material (FGM) deep spherical shells are analyzed. One surface of the shell is kept at the reference temperature while the other one is subjected to rapid surface heating. Based on the theory of uncoupled thermoelasticity, the one-dimensional heat conduction equation across the thickness of the shell is developed and solved using the combined Crank–Nicolson method and the central finite difference method. The temperature profile obtained from the numerical solution of the heat conduction equation is used to calculate the thermal forces and the thermally induced bending moment to insert into the equations of motion of the shell. Under the assumptions of the first-order shear deformation theory (FSDT), uncoupled thermoelasticity laws, the von Kármán type of geometrical nonlinearity, and employing the Hamilton principle the axisymmetric equations of motion are obtained. The conventional multi-term polynomial Ritz method is used to discretize the governing nonlinear equations of motion. To convert the differential equations of motion into algebraic equations in each time step, the β-Newmark time marching scheme is used, and the obtained equations are solved with the help of the Newton–Raphson linearization method. In some cases, the dynamic buckling temperature is detected using the Budiansky criterion. Various numerical results are presented to analyze the effects of different parameters such as the opening angle of the shell, the thickness of the shell, and the power law index of the material composition rule.

Application of 2D coupled algorithms to thermally induced dynamics of temperature-dependent nanocomposite cylindrical panels under transient heat shock

The current investigation examines the thermal wave motion in a functionally graded cylindrical panel with carbon nanotubes exposed to rapid surface heating. The equivalent temperature-dependent material properties of the nanocomposite media are achieved by employing a modified homogenization technique. Due to the time-dependent nature of the applied heat function, the heat conduction equation is calculated transiently. Furthermore, due to the temperature dependency of the properties, the heat conduction equation is nonlinear and is solved by the combined finite-difference and Picard methods. The Crank–Nicolson time solving scheme is utilized to determine the temperature profile of each composite system point across time. The first-order shear deformation and Donnell strain theories regulate the system’s motion equations. The combined 2D generalized differential quadrature and Newmark procedures are implemented to numerically simulate the composite structure’s physical variables. Following verification, the effects of composite media parameters and panel characteristics on the shell reaction subjected to thermal shock are examined.

Vibrations of graphene platelet reinforced composite doubly curved shells subjected to thermal shock

An investigation is performed in this research to study the response of doubly curved shells subjected to rapid surface heating. Doubly curved shell is made from a composite laminated media where each layer is reinforced with graphene platelets (GPLs). Also each layer may have different amount of GPLs which results in a piecewise functionally graded graphene platelet reinforced composite (FG-GPLRC) shell. The elasticity modulus of the shell is estimated by means of the Halpin-Tsai rule where the size of the reinforcements is also included. It should be noted that mass density, thermal expansion coefficient, Poisson’s ratio and specific heat are evaluated using the simple rule of mixture approach. The one-dimension transient heat conduction equation is established and solved for each layer of the composite media. The continuity of the temperature change and heat flux are also considered between the layers. After that, time dependent thermal moment and thermal force are evaluated and inserted into the equations of motion of the structure. First order shear deformation theory of shells and Donnell kinematics are applied to establish the basic equations of the shell. With the aid of the Ritz method and Chebyshev polynomials as the basic functions, the matrix representation of the motion equations of the doubly curved shallow shells subjected to rapid surface heating are established. These equations are traced in time using the Newmark time marching scheme. Results of this study are compared with the available data in the open literature. After that novel results are provided for vibrations induced by rapid surface heating in FG-GPLRC doubly curved shells.

Dynamic snap-through of functionally graded shallow arches under rapid surface heating

In this paper, dynamic buckling response of a shallow arch constructed from functionally graded materials under thermal shock is investigated. It is assumed that one surface of the beam is subjected to sudden temperature elevation while the other surface is kept at reference temperature. To solve the one-dimensional Fourier heat transfer equation, Crank–Nicolson numerical method along with the central finite difference method are employed. In order to obtain the strain–deflection relations, Donnell theory of shallow arches with von Kármán simplifications are used. The governing equations are acquired based on well-known Hamilton’s principle that are converted to a set of non-linear algebraic equations using the Ritz method. Since the governing equations are non-linear equations, the Newton–Raphson method is applied and after that temporal evolution of displacements are obtained employing the Newmark time marching scheme. In the final stage, a theory to estimate the buckling load is required, which is the Bodiansky–Roth criterion in this research. To validate the formulation and solution method of this project, this work is compared with previous studies and good agreement is obtained. In addition, impacts of power law index, arch thickness, geometrical parameters, and temperature dependency on the dynamic buckling temperature are reported in this study.

Application of Ritz method to large amplitude rapid surface heating of FGM shallow arches

Application of Ritz method to large amplitude rapid surface heating of FGM shallow arches

Pulsed laser surface heating: A tool for studying pyrolysis product chemistry in molecular beams

Laser pulses directed at surfaces can produce rapid and intense surface heating. Heating from laser pulses out of the absorbance range of compounds on the surface will cause compound desorption; pyrolytic products increase at higher pulse energies. Depending on the timing of the photoionization or ion extraction, species in different portions of the gas pulse can be mass analyzed. Using “thermometer” ions to characterize the results, we show that it is possible to study either lower or higher temperature regime pyrolysis products. It is possible to query initial pyrolytic products that have undergone either more or less subsequent associative chemistry.

A unified formulation for thermoviscoelasticity of hollow sphere based on the second sound theories

By proposing the unifier factors, a unified formulation for the generalized coupled thermo-visco-elasticity response of hollow spheres based on the Lord–Shulman, Green–Lindsay, and Green–Naghdi models is developed. Kelvin–Voigt model is used in the current research to consider the viscoelastic response of the sphere. This formulation is used to capture the thermoviscoelastic response of finite isotropic hollow sphere under thermal shock. After transforming the one-dimensional radial equations into the non-dimensional form, finite element method (FEM) based on the Galerkin weak formulation is implemented. The governing equations are discretized through the radial domain utilizing FEM. The determined system of ordinary differential equations is traced using the average acceleration method as a type of Newmark time marching scheme. After validation, novel numerical results are demonstrated to analyze the influences of viscoelastic damping on the response of hollow sphere under rapid surface heating based on various types of generalized theories.

Delivery of inert gas through a vertical borehole using inert gas generator: A theoretical study

The delivery of the inert gas through a vertical borehole using inert gas generator or IGG is investigated. Potential limitations and/or transient effects are highlighted. During the analysis, the borehole diameter, borehole length, type of borehole and partial condensation prior to entering the borehole were varied. A choked flow will occur for a contraction exit or borehole of 0.3 m in diameter if no condensation prior to the contraction occurs. If partial condensation takes place, a borehole diameter of 0.3 m will be possible if almost 50% of the water vapour condensates. However, pressure losses along boreholes with a diameter of 0.3 or 0.4 m are significant and could pose a challenge if trying to mitigate the pressure losses. Adding a booster fan prior to the inlet of the 0.4 m lined borehole would still be a challenge. The corresponding case with a 0.5 m borehole presents much more favourable pressure losses. The 0.5 m diameter lined borehole should be regarded as the lower threshold. The rapid heating of the unlined borehole surface will increase the risk of thermal spallation and possibly imposing restrictions. Understanding the mechanisms during gas delivery will increase the likelihood of a successful inertisation.

Review of pool boiling critical heat flux (CHF) and heater rod design for CHF experiments in TREAT

Preventing the occurrence of a departure from nucleate boiling (DNB) event is an important aspect of nuclear safety in pressurized water reactors (PWRs). This phenomenon is partially governed by the cladding-to-coolant heat transfer under transient irradiation conditions, such as during a reactivity-initiated accident (RIA). Currently, there are large uncertainties about cladding-to-coolant heat transfer under these rapid transient conditions. This effort aims to elucidate the mechanisms of CHF under in-pile fast transient irradiation conditions using the Transient Reactor Test (TREAT) facility. These experiments will be carried out under pool boiling conditions, within experimental capsules that will be inserted into the TREAT reactor. A heater rodlet made from stainless steel 304 with tailored natural boron content will be usedin these experiment capsules to induce CHF when submitted to a TREAT power pulse. We will investigate the impacts of the presence of an oxide layer, radiation-induced surface activation (RISA), heat transfer time constant, and rapid surface heating effects on the CHF phenomenon.We review the parameters with significant effects governing the predictions of pool boiling CHF. Only CHF influencing parameters that are highly important, among them coolant subcooling and pressure, as well as oxide layer thickness, RISA, and rapid heating effects were included in this literature assessment.Preliminary neutronics and thermal hydraulic results from the design of the experimental apparatus are also presented in this paper. To aid in the modeling approach, the energy deposition and occurrence of CHF were identified as the most crucial key Figures of Merit (FoMs).In the heater rod design, boron concentrations between 0.1 and 2.09 wt% were considered. Further, a self-shielding study was performed to determine whether an instrumented borated tube could be used in place of a solid borated rod. This study determined that the inner region of the rod can be excluded or instrumented without heat generation penalties. Lastly, a thermal-hydraulics sensitivity study determined the lowest limiting boron concentration needed to induce CHF in water with different degrees of subcooling. Additionally, the value of CHF is known to increase during a rapid transient. Therefore, a CHF multiplier sensitivity study determined what multipliers would inhibit CHF for varying degrees of subcooling of two chosen power coupling factors (PCFs). The current borated tube rodlet geometry configuration achieved a maximum CHF multiplier value of 7.8 using a 1400 MJ power pulse in TREAT. Although this was the power pulse with the greatest energy deposition considered for this study, the TREAT facility is capable of pulses up to ~2500 MJ. This provides a significant margin in energy capacity that was not included within the scope of the calculations carried out to date.The application of the heater rod design was successfully demonstrated in initial experiments in December 2019. The results of these experiments will be explored in future publications.

Study of Heating Devices Based on a First-Order Phase Transition

New developments aimed at saving costs for heating a house are attracting more and more attention. The development of highly efficient heating radiators that meet the requirements of modern engineering systems, namely: cost-effectiveness, efficiency, rapid uniform heating of the entire surface, ease of installation and operation, low manufacturing costs and durability is the main direction in the design of heating devices. In recent years, the use of heating radiators based on first-order phase transition has been gaining ground in heating systems in Ukrainian cities. In the literature and on the Internet resource s , there is another name for such kind of the radiators – vacuum radiators. T hey were named because air was completely pumped out of the internal cavity of the sectional structure. This is done in order to reduce the pressure and, accordingly, reduce the evaporation temperature of the secondary coolant. These are ordinary heating appliances externally, but completely different in principle of operation. In fact, the operation of the vacuum radiator is built on the principle of functioning of a sealed two-phase thermosiphon. The main advantage of such solution is the unique coolant circulation system. They can be used both for heating systems and for autonomous ones. There are conflicting opinions about the advisability of using vacuum radiators, so their confirmation or refutation requires in-depth research. This paper presents the results of experimental studies of a heating radiator based on first-order phase transition. As a secondary coolant, a liquid with a low boiling point is used. The principles of operation of the heating device are investigated, thermal capacities are determined at various temperatures of the coolant. A comparison is made with traditional steel and aluminum radiators, . Particular attention was paid to the study of vacuum radiators from the point of view of heat exchange, and their unusual properties were noted. The main advantages and disadvantages of this heating device are revealed. The ways of further research of these types of heating radiators are indicated.

Replication of high refractive index glass microlens array by imprinting in conjunction with laser assisted rapid surface heating for high resolution confocal microscopy imaging

In a multi optical probe confocal imaging system utilizing a microlens arrays as an objective lens, a high numerical aperture is required to improve resolving power. Glass microlens arrays are suitable for high-resolution imaging since they provide outstanding optical properties with a high refractive index. We demonstrated the rapid fabrication of microlens arrays on a high refractive index optical glass substrate via laser assisted thermal imprinting. The optical performance of the fabricated glass microlens arrays were evaluated and compared to that of a polymer microlens. In contrast to the polymer, the real image afforded by, and the calculated resolution of, the imprinted glass microlens arrays were significantly better, at about 0.73 µm compared to the polymer (∼1.56 µm). Our results reveal the considerable potential of direct thermal imprinting as a rapid, single-step, low cost fabrication method for replication of glass microlens array of high dimensional accuracy affording excellent optical performance.

Geometrically nonlinear rapid surface heating of temperature-dependent FGM arches

Based on the nonlinear dynamic analysis, thermally induced vibrations of the FGM shallow arches subjected to different sudden thermal loads are studied. Temperature and position dependence of the material properties are taken into account. Based on the uncoupled thermoelasticity assumptions, The non-linear one-dimensional transient heat conduction equation is solved numerically by a hybrid iterative GDQ method and Crank-Nicolson time marching scheme. A first order shear deformation arch theory (FSDT) is also combined with the von Kármán type of geometrical non-linearity and the Donnell kinematic assumption to obtain the equations of motion employing the Hamilton principle. Discretization of the highly coupled non-linear equations of motion is done by using the GDQ method in the arch domain. The solution of the system of the ordinary differential equations is established by means of a hybrid iterative Picard-Newmark scheme. Comparison is also made with the existing results for the case of isotropic homogeneous shallow arches, where good agreement is obtained. Also, parametric studies are proposed to show the effects of temperature dependency, geometrical non-linearity, arch thickness, power law index, and the type of thermal-mechanical boundary conditions upon the arch deflection.