Thermomechanical State Research Articles

Mathematical Modeling of High-Energy Shaker Mill Process with Lumped Parameter Approach for One-Dimensional Oscillatory Ball Motion with Collisional Heat Generation

This study presents an advanced mathematical model for the high-energy shaker mill process, incorporating thermal interactions among the milling ball, shaker mill vial, and the air contained within. Unlike previous models focusing solely on the ball’s temperature, this research emphasizes the heat produced by impacts and the thermal exchange among all three components. Incorporating these thermal interactions allows the model to provide a more comprehensive depiction of the energy dynamics within the system, leading to more precise predictions of temperature changes. Utilizing a lumped parameter method, the study simplifies complex airflow dynamics and non-uniform temperature distributions in the milling system, enabling efficient numerical analysis. Hamilton’s equations are extended to include supplementary state variables that account for the internal energies of both the vial and the air, in addition to the thermomechanical state variables of the ball. High-energy milling techniques are essential in mechanochemical synthesis and various industrial applications, where the optimization of heat transfer and energy efficiency is crucial. Numerical simulations computed using the Bogacki–Shampine integration algorithm significantly align with experimental data, confirming the model’s accuracy. This comprehensive framework enhances understanding of heat transfer in one-dimensional ball motion, optimizing milling parameters for better performance. The mathematical model facilitates the computation of heat production due to collisions, based on operational parameters like shaking frequency and amplitude, thereby allowing for the anticipation of chemical reaction activation potential in mechanochemistry.

Diverse intrusion modes during the construction of a high-silica magma reservoir: Evidence from La Obra–Cerro Blanco intrusive suite (central Chile)

Abstract Several conceptual models have been proposed for the amalgamation of granitoid plutons, which range from incremental growth to single-stage emplacement of these systems. This diversity of views has led to intense debate about the thermomechanical state of silicic intrusions and the magma differentiation paths within the crust. In this contribution, we present a comprehensive petrologic, geochronologic, and magnetic fabric data set from the La Obra–Cerro Blanco intrusive suite, which allows us to explore the petrogenesis and magma emplacement processes in the upper crust. This intrusive suite is composed of (1) a vertically zoned granitoid intrusion in spatial association with mafic layers and stocks and (2) a cupola-like high-silica granite. We interpret this intrusive suite as assembled by diverse but coexisting intrusion mechanisms over a time span of ~1.4 m.y. from 21.4 to 19.9 Ma. As indicated by the subhorizontal magnetic lineation, the first stage was dominated by horizontal emplacement of sheet-like intrusions of intermediate compositions, which became increasingly silicic after plagioclase and amphibole fractionation throughout the crustal column. The latest stage was instead dominated by cooling, crystallization, and differentiation of a thickened granitoid body and the formation of a high-silica magma chamber. The steep magnetic lineation and the abundance of aplite and rhyolitic dikes observed in the cupola-like, high-silica granites suggest that this portion acted as an evacuation channel of high-silica magma toward shallower levels, offering a rare opportunity to understand not only silicic magma accumulation and storage in the upper crust, but also the processes connecting the plutonic and volcanic environments.

Geophysical evidence for the North Pie de Palo Lineament in the Precordillera

The Precordillera fold-thrust belt, situated within the Pampean flat-subduction segment (27°–33°S), is characterised by enigmatic transversal structures which extend and influence deformation patterns, the full extent of which is yet to be fully elucidated. The Northern Pie de Palo Lineament represents a key example, and has been proposed to play a pivotal role in the development and structural control of the Precordillera. In any case, this lineament has not been subjected to a comprehensive study, which has led to ongoing debate regarding its structural control, persistence, and morphology. This study was therefore focused on this structure, employing multiple geophysical methodologies, including aeromagnetic and gravimetric techniques. This approach enabled the first visualization of the full extension and fault zone of the North Pie de Palo Lineament, which crosses the entire Precordillera fold-thrust belt in a transverse direction. Consequently, it can be posited that this structure would have exerted a conditioning influence on the thermo-mechanical state of the Andean lithosphere, enabled the uplift of mafic bodies and thus influenced the Neogene deformation of the Precordillera fold and thrust belt. The confirmation and characterization of this major structure open new perspectives on the interaction of deep-seated transversal structures with fold belts during the evolution of the southern central Andes.

Ab-initio insights into the physical properties of XIr3 (X = La, Th) superconductors: A comparative analysis

Here we report the structural, elastic, bonding, thermo-mechanical, optoelectronic and superconducting state properties of recently discovered XIr3 (X = La, Th) superconductors utilizing the density functional theory (DFT) using two different exchange-correlations functionals. The elastic, bonding, thermal and optical properties of these compounds are investigated for the first time. The calculated lattice and superconducting state parameters are in reasonable agreement to those found in the literature. In the ground state, both the compounds are mechanically stable and possess highly ductile character, high machinability, low Debye temperature, low bond hardness and significantly high melting point. The thermal conductivities of the compounds are found to be very low which suggests that they can be used for thermal insulation purpose. The population analysis and charge density distribution map confirm the presence of both ionic and covalent bonds in the compounds with ionic bond playing dominant roles. The calculated band structure and DOS profiles indicate metallic character of XIr3 compounds. It is also found from the DOS profile that the Ir 5d-states dominate near the Fermi level. Unlike the significant anisotropy observed in elastic and thermal properties, all the optical constants of XIr3 compounds exhibit almost isotropic behavior. The optical parameters’ profiles correspond very well with the electronic band structure and DOS features. We have estimated the superconducting transition temperature (Tc) of XIr3 compounds in this work. The calculated values of Tc for LaIr3 and ThIr3 compounds are 4.91 K and 5.01 K, respectively. We have compared and contrasted all the physical properties of XIr3 (X = La, Th) compounds in this study.

A thermo-mechanical model for hot cracking susceptibility in electron beam powder bed fusion of Ni-base superalloys

Hot cracking is a major challenge in the additive manufacturing of Ni-base superalloys. Most cracking indicators only consider the alloy composition and its effects on solidification behavior, strength, and ductility. We propose a new model that extends these classical cracking indicators by additionally incorporating the transient thermo-mechanical state during melting and solidification. The model is derived from insights into the cracking of thin layers and is mainly based on the elastic strain energy available to drive crack opening in a critical temperature interval. The underlying thermo-mechanical process simulations are implemented in a custom computational framework designed to efficiently model powder bed fusion. The model predictions are validated against experimentally measured crack densities in CMSX-4 processed by electron beam powder bed fusion. The proposed model allows for rationalizing the dependence of cracking susceptibility on the thermal history, which is controlled by scan speed and beam power. Finally, the model is applied to develop a crack mitigation strategy by reducing the built-up strain energy density. This is achieved by heating the melting area to a high temperature before melting, thereby reducing the temperature gradient.

Space Silicone Adhesive Monitoring Via Minimally Intrusive Optical Fibre Sensing During Vacuum UV/VUV Radiation Exposure

In this work a technique to monitor the health state of space adhesives during environmental testing is presented. Specifically, minimally intrusive Tilted Fibre Bragg Grating (TFBG) sensor was embedded in silicone adhesive Nusil CV16-2500 used to bond two thin cover glasses. The resulting solar cell assembly was then exposed to the UV/VUV radiation in a high vacuum chamber (less than 10-5 mbar). The sensor is demonstrated that it was able to measure simultaneously the strain, temperature and refractive index of the adhesive. The three parameters measured with the TFBG, can be used to detect the thermomechanical and refractometric state of the silicone adhesive.

On the use of an induced temperature gradient and full‐field measurements to investigate and model the thermomechanical behaviour of an austenitic stainless steel 316

AbstractA temperature gradient was induced in 316 stable austenitic stainless‐steel tension specimens, and the strain and temperature evolution during tensile deformation was monitored using optical and infrared cameras. The combination of global load with full‐field strain and temperature provided local information on the thermomechanical state of the investigated material. The deformation did not fully concentrate on the hotter portion of the specimen, but instead, the hottest portion strain hardened enough so that the colder portions of the specimen also experienced plastic deformation. Evidently, heat release occurred with plastic deformation and altered the initial temperature gradient as deformation progressed. The Taylor–Quinney coefficient was computed in integral and differential forms, and both are presented as a function of temperature and strain. The Johnson–Cook plasticity model was calibrated through an inverse method procedure in which only five tests were used, and the obtained temperature and strain rate dependencies of the model were comparable to those found in the literature for the same material. A local analysis was done to quantify the impact of adiabatic heating on the mechanical behaviour of the material.

Zadacha o neideal'nom teplovom kontakte

We consider the problem of determining the thermomechanical state of a fuel element in a nuclear reactor. A finite element algorithm for solving the thermal problem together with the problem of mechanical contact is described, and a model one-dimensional problem is studied to clarify the main features and a numerical algorithm for solving it. The leading term of the asymptotic expansion of the solution of this problem and a difference scheme for its solution, including iterative methods, are constructed. A cycle of test calculations is carried out to confirm the theoretical estimates. The comparison of calculations for real problems with theoretical predictions shows that the algorithm for solving a multidimensional nonlinear problem qualitatively corresponds to the behavior of one-dimensional calculations.

Safety analysis of VVER fuel rod modelling in reactivity initiated accident

The paper briefly reviews the behaviour of WWER type fuel rods studied under conditions of a high rate of power rating of fuel; the investigations were carried out to validate the licensing criteria with the aim of assessing design basis reactivity initiated accidents (RIA).The procedure used to calculate thermomechanical and corrosion behaviour of fuel rods in accidents is described.The results acquired from the analysis of the thermomechanical condition of WWER-1000 fuel rods in a design basis reactivity initiated accident caused by an ejection of a regulation element of the control and protection system (RE CPS) are discussed.The aim of the analysis is to validate the fulfillment of specific safety requirements imposed on fuel rod condition in design basis accidents.Consideration is given to accidents attended with a rise of fuel rod (fuel and/or cladding) temperature in comparison to the state under normal operating conditions. This may proceed from deterioration of heat transfer from fuels, e.g., in accidents due to loss of the coolant by the primary circuit or an increase in power rating of fuel in RIA.Design procedures have been worked out to simulate fuel rod behaviour in accidents, which were implemented in the RAPTA-5 fuel performance code. Using the latter, design analysis of fuel rod behaviour under design RIA conditions is implemented; its results serve to draw conclusions whether acceptance criteria are fulfilled.The results of the RAPTA-5 code design analysis of the thermomechanical state of WWER-1000 fuel rods in that accident have demonstrated the fulfillment of all the acceptance criteria.

Multiparameter Single Sensor for Space Silicone Adhesive Monitoring Under High-Vacuum Ultraviolet Exposure

Tilted fiber Bragg grating (TFBG) sensors were demonstrated to simultaneously measure the material thermomechanical and refractometric state in which they are embedded. In this work, for the first time, TFBGs are investigated for three-parameter monitoring of space-qualified NuSil® CV16-2500 silicone operating during high-vacuum ultraviolet (UV) exposure. The first part of the work is focused on the ultraviolet effect on the TFBG spectrum when the sensor is 1) directly exposed to the radiation, 2) covered by a thin cover glass, and with a Kapton layer on top. Successively, the silicone is used as an adhesive in a sandwich structure in which the TFBGs are embedded and exposed under high vacuum to various UV/vacuum UV intensity radiations and durations. The sensors’ spectra were acquired and demodulated to detect the silicone strain–temperature–refractive index variations and correlate the silicone refractometric changes with the equivalent exposure solar hours. The second part of the paper is on silicone degradation state evaluation using the same sensor but during a direct exposure of the adhesive to the radiation. This allowed the UV effects on the silicone to be enhanced but needed a method to compensate for the damaging effect of UV radiation on the TFBG spectrum.

Basic principles in the theory of force and thermal force resistance of concrete

In the development of the ideas and approaches to the analysis of the force resistance of concrete of V.M. Bondarenko, the initial prerequisites for the model of the thermomechanical state of concrete under short-term sharp high-temperature exposure, characteristic of fire conditions, are formulated. The separation of force deformations into components is carried out on the basis of the connection with the accumulation of damage in the structure of the material, based on the principle of independence of the limiting structural stresses from temperature and the mode of force action, which makes it possible to establish basic thermomechanical relationships and determine the deformation parameters of concrete operating under conditions of unsteady heating in a loaded state. Based on the extension of the hypothesis of entropy damping of nonequilibrium processes to the area of action of an active destructive factor, the principle of normalization was formulated and a kinetic equation was proposed, from the solution of which exponential dependences having a single structure were obtained, which make it possible to describe the basic temperature parameters of concrete, the relationship of stresses with deformations, and other nonlinear characteristics. The application of the proposed principles creates a reliable theoretical basis for describing the mechanisms of thermal resistance of concrete and greatly simplifies the modeling of the effect of high temperature on the properties of concrete in the practical implementation of methods for the numerical calculation of reinforced concrete structures.

Impact of the thermo-mechanical behavior of elastomeric membrane on the flight dynamics of sounding balloons

The following work deals with the coupling of a thermo-mechanical model (TMM) of elastomeric membranes of sounding balloons with a flight dynamics model (FDM) of the whole system composed of a sounding balloon and its gondola. This type of balloon, filled with Helium gas, is typically used for its low cost to conduct tests of space technologies in near-space conditions between 20 km and 40 km above sea level where low pressure of the order of millibar can be found. The coupling between the TMM and the FDM is held by the rate of expansion of the balloon. The rate of expansion depends on the mechanical state of the membrane given by the surrounding atmospheric conditions. The model is used to assess the burst altitude, the time of flight during the ascent and the impact velocity of the gondola at the final stage of the descent. A generic model of the atmospheric conditions provides the necessary aerodynamic parameters to describe the balloon ascent to its final altitude. Special attention is given to the balloon membrane as it is subjected to constant changes of pressure during the ascent. The TMM is built to include the details of the temperature-dependent stress–strain relation experienced by the elastomeric membrane as a function of altitude. Knowing its thermo-mechanical state during the flight allows predicting with greater accuracy the burst altitude and the flight duration than provided by a sole FDM. However, in a thorough effort to understand the limitation of the proposed TMM, its results are compared against those computed from classic hyperelastic models showing key differences. Nevertheless, these differences do not translate into any significant impact on the flight dynamics as shown in the comparison between simulation results and experimental data (time of flight, altitude versus time and impact velocity) obtained for three actual flights that occurred over the State of Guanajuato, Mexico, in 2015 (flight F1), 2016 (flight F2) and 2018 (flight F3). It is argued that the present thermo-mechanical flight dynamic model (TMFDM) can be applied to the fair estimation of the flight duration and the burst altitude with sufficient knowledge of the atmospheric conditions. The model can provide key information for the suborbital flight. Amongst these key information, the maximum altitude reached by the balloon is essential to estimate the impact velocity and subsequently to design reliable impact attenuators to ensure the physical integrity of the payload when the gondola touches the ground. The same information can also be used to determine the operating conditions of payloads in high altitudes. Additionally, the time of flight may be used to plan ahead of time the duration of the tests to be performed in a near-space environment.

Surface or Internal Fatigue Crack Initiation during VHCF of Tempered Martensitic and Bainitic Steels: Microstructure and Frequency/Strain Rate Dependency

By means of comparing the VHCF response of heat-treated alloy steel, several factors governing the transition from surface (type I) to internal (type II) VHCF failure, and, in the case of internal inclusion and non-inclusion type II VHCF failure, are discussed: differences in strength, differences in grain size and strength gradients. Therefore, the steel grades (i) 50CrMo4 (0.5 wt%C–1.0 wt%Cr–0.2 wt%Mo) in two different tempering conditions (37HRC and 57HRC) but of the same prior austenite grain size, and (ii) 16MnCrV7 7 (0.16 wt%C–1.25 wt%Mn–1.7 wt%Cr) in the bainitic and martensitic thermomechanical treatment state, were studied. It is concluded that steels of moderate strength (37HRC) exhibit a real endurance limit (109 cycles), while the fatigue strength of high strength (43–57HRC) or coarse-grained steels (37HRC) decreases with increasing number of load cycles.

Inverse identification of material constitutive parameters based on co-simulation

Establishing a material constitutive model reflecting the mechanical behavior of metal materials in the cutting process is the basis of cutting finite element simulation, and has an important guiding role in accurately describing the cutting thermo-mechanical coupling state variables and further optimizing process parameters. This paper proposes a reverse identification method of material constitutive parameters based on co-simulation. The influence of mass scaling factor, mesh size, and Johnson-Cook (J-C) constitutive parameters on cutting force was analyzed, and orthogonal cutting experiments were carried out for two difficult-to-machine materials, die steel H13 and titanium alloy Ti-6Al-4V. ABAQUS is redeveloped based on Python, and then the J-C constitutive parameters are directly optimized for the first time with the minimum error between the finite element simulation value and the experimental value of the cutting force as the objective function, the least square identification of J-C constitutive parameters based on co-simulation is realized by combining genetic algorithm. The results show that the reasonable setting of mass scaling factor and mesh size can significantly reduce the time of simulation calculation and improve the optimization efficiency of constitutive parameters. The yield stress, hardening coefficient, strain rate coefficient, hardening coefficient and softening coefficient of materials have different effects on cutting force, which is the key to effective inverse identification of constitutive parameters. Compared with different J-C parameters reported in the literature, it is found that the constitutive parameters obtained by inverse identification based on co-simulation are more accurate, and the prediction of residual stress and serrated chip characteristics also has good accuracy. This study provides a reference for the optimization of constitutive parameters, and the research results provide a new scheme for the efficient construction of material mechanical behavior required for cutting finite element simulation.

Building energy model validation and estimation using heating and cooling degree days (HDD–CDD) based on accurate base temperature

AbstractA great deal of energy used in buildings is directed toward heating, ventilation, and air‐conditioning (HVAC). The key procedure in reducing heating and cooling loads is the creation of a baseline model that represents a theoretical version of the building. This allows multiple scenarios to balance the lowest retrofit cost with the lowest annual energy cost. This study emphasizes establishing an energy consumption model and energy benchmarks for a commercial building located in Shiraz, Iran. The energy‐related data are gathered for 3 years based on real values from billing receipts. Herein, two distinct approaches are integrated; forward and inverse methods. In the forward method, building energy consumption is predicted based on building performance and specifications, geometry, location, and air conditioning system. In the reverse method, building energy consumption is evaluated using the building load coefficient and building base consumption according to effective factors such as weather data and appliance performance. Also, considering constant fixed temperatures as 18°C, and 21°C for calculating heating and cooling degree days is not correct. Thus, finding a proper and valid base temperature is the main aim of this study by examining this integrated method. The integrated application of these methods allowed determining the thermomechanical state of the building as a whole. To this end, base temperature boundaries are extracted from the energy consumption trend which grounds the need for cooling and heating. Eventually, the baseline for energy consumption of the building based on the proposed method is provided for calculating the development of methodological foundations for the design, construction, operation, and renovation of energy‐efficient buildings. The results show that according to an acceptable thermal building comfort zone of 14–18.6°C, the building achieves a 30 percent reduction in annual cooling and heating energy consumption compared to the base year.

Thermomechanical investigation of the continuous casting of ingots using the element-based Finite-Volume Method

A computational thermomechanical simulator using the Element-based Finite-Volume Method (EbFVM) has been elaborated to investigate the solidification of continuous casting ingots. The thermal behavior was evaluated using the two-dimensional transient heat conduction equation with phase change in conjunction with numerical-experimental film coefficients. In addition, the thermal-mechanical approach includes three inelastic representations, which are based at the Ramberg-Osgood plastic and Odqvist's viscoplastic models. The simulator is validated using several benchmarks tests, along with the analytical solution of the Stefan's problem. In the context of continuous casting, in order to enhance the cooling stage in the spray zone, as well as the crack formation, a new set of sprays were proposed for the investigated case. The thermomechanical study provided by EbFVM is able to provide good results for the temperature profile and thermomechanical state that could be used to address problems caused by the cooling process of continuous casting of ingots.

Dynamic response of polycrystalline high energetic systems: Constitutive modeling and application to impact

This paper presents a new polycrystalline model and Lagrangian computational framework for describing the large-scale thermo-mechanical response of energetic materials under dynamic loadings. In our multi-scale computational polycrystalline framework, at the grain level, the elastic response is modeled using an anisotropic Hooke's law, while the plastic behavior is described with a recently developed quadratic anisotropic single-crystal model that accounts for the intrinsic symmetries associated with the lattice of the constituent crystals. The orientation, plastic strains, and stresses in the individual grains are continuously updated, so the predicted macroscopic scale response takes into account the evolution of the thermo-mechanical state at the meso-scale. First, we illustrate the polycrystalline model capabilities by simulating the response of a pentaerythritol tetranitrate (PETN) polycrystalline high energetic system when subjected to dynamic compression. It is shown that there are strong differences in temperature and stresses between the constituent grains, depending on their relative orientation with respect to the wave direction. Moreover, it is shown that the rise in temperature in certain grains may be well in excess of the macroscopic value. We also present 3D finite element simulations of the impact of a penetrator made of a high-strength steel containing the same polycrystalline PETN system. Insights into the complex interactions between the energetic system and the metallic casing material are provided. Furthermore, it is shown that if the crystallinity is neglected, the predicted temperature rise and the extent of the zone of maximum heating in the energetic system during the impact event differ noticeably from those obtained with our polycrystalline model, which accounts for the crystallinity of the PETN material and the anisotropy in the plastic flow of its constituent crystals.

The Potential Energy Hotspot: Effects of Impact Velocity, Defect Geometry, and Crystallographic Orientation

In energetic materials, the localization of energy into when a shock wave interacts with the material's microstructure is known to dictate the initiation of chemical reactions and detonation. Recent results have shown that, following the shock-induced collapse of pores with circular cross-sections, more energy is localized as internal potential energy (PE) than can be inferred from the kinetic energy (KE) distribution. This leads to a complex thermo-mechanical state that is typically overlooked. The mechanisms associated with pore collapse and hotspot formation and the resulting energy localization are known to be highly dependent on material properties, especially its ability to deform plastically and alleviate strain energy, as well as the size and shape of the pore. Therefore, we use molecular dynamics simulations to characterize shock-induced pore collapse and the subsequent formation of hotspots in TATB, a highly anisotropic molecular crystal, for various defect shapes, shock strengths and crystallographic orientations. We find that the the localization of energy as PE is consistently higher and its extent larger than as localized as KE. A detailed analysis of the MD trajectories reveal the underlying molecular process that govern the effect of orientation and pore shape on the resulting hotspots. We find that the regions of highest PE for a given KE relate to not the impact front of the collapse, but the areas of maximum plastic deformation, while KE is maximized at the point of impact. A comparison with previous results in HMX reveal less energy localization in TATB which could be a contributing factor to its insensitivity.

Asymptotic analysis of the transient response of a thermoelastic assembly involving a thin layer

We study the transient response of a thermoelastic structure made of two tridimensional bodies connected by a thin adhesive layer. Once more we highlight the powerful flexibility of Trotter's theory of approximation of semi-groups of operators acting on variable spaces: considering the geometrical and physical characteristics of the thin layer as parameters, we are able to show in a unitary way that this situation leads to a huge variety of limit models the properties of which are detailed. In particular, according to the relative behaviors of the different parameters involved, new features are evidenced such as the apparition of an added specific heat coefficient for the interface or of additional thermomechanical state variables defined not only on the limit geometric interface but on its cartesian product by any interval of real numbers.

Battery-Free Shape Memory Alloy Antennas for Detection and Recording of Peak Temperature Activity

Economical sensing and recording of temperatures are important for monitoring the supply chain. Existing approaches measure the entire temperature profile over time using electronic devices running on a battery. This paper presents a simple, intelligent, battery-free solution for capturing key temperature events using the natural thermo-mechanical state of a Shape Memory Alloy (SMA). This approach utilizes the temperature-induced irreversible mechanical deformation of the SMA as a natural way to capture the temperature history without the need for electronic data logging. In this article, two-way SMA is used to record both high-temperature and low-temperature peak events. Precise thermo-mechanically trained SMA are employed as arms of the dipole antenna for Radio Frequency (RF) readout. The fabricated antenna sensor works at 1 GHz and achieves a sensitivity of 0.24 dB/°C and −0.16 dB/°C for recording temperature maxima and minima, respectively.