Thermal Analysis Procedure Research Articles

Effective thermal conductivity of composites using homogenization

Composite materials are extensively used in engineering applications due to their customizable properties and high performance. Determining the equivalent homogenized properties of composites, such as thermal conductivity, is crucial for their effective use. Various theoretical, analytical, and experimental methods have been developed to assess these properties. This study investigates the effective thermal conductivity of composites using a deterministically based procedure for thermal analysis. This procedure accounts for the combined influences of the inclusions’ volume fractions, shapes, orientations, and locations within the matrix to determine the effective thermal conductivity of composites. The specific composite analyzed consists of a cubical PLA matrix with a single spherical or elliptical void inclusion with perfect interfaces. For that purpose, an analytical approach was developed, and MATLAB® code was created to calculate the effective thermal conductivity tensor. To benchmark the analytical results, comparisons were made against numerical finite element modeling (FEM) results conducted using ANSYS®; in addition, to previously reported analytical models from the literature. Corroboration was also obtained by comparing the results against experimental data from the literature. The accuracy of the proposed homogenization scheme was demonstrated by achieving a low mean absolute percentage error (MAPE) compared to FEM (2.88%) and to the experimental results (2.72% for void inclusion and 6.99% for filled inclusion). Additionally, a high R-squared (R2) value of 0.986 was achieved compared to FEM, and values of 0.97 and 0.998 were achieved compared to the experimental results for void and filled inclusions, respectively.

Considerations for the safe handling and processing of unstable materials

AbstractWe evaluate the instability hazards of initiators, monomers, and other unstable materials during storage and handling in individual containers, pallets of containers, and storage and process vessels. We propose a simplistic model to analyze the temperature–time profile of an unstable chemical, given heat transfer from/to the environment, heat generation due to decomposition and other reaction kinetics, and heat generated from auxiliary equipment (e.g., agitators/mixers, pumps, vessel jackets). Lumped capacitance‐based heat transfer and decomposition kinetics are integrated to predict self‐accelerating decomposition temperature (SADT), self‐accelerating polymerization temperature (SAPT), and the temperature profile given exposure conditions (e.g., ambient temperature and additional sources of heat). Case studies related to the storage and processing of unstable liquid monomers (i.e., methyl methacrylate, MMA), and organic peroxides, (i.e., tert‐butyl peroxybenzoate, TBPB), are presented. We also provide recommendations on determining safe storage and processing temperatures and steps to prevent emergency situations and include an overview of thermal analysis and data treatment procedures which might affect chemical process safety recommendations.

Analyzing cold hardiness (Based on DTA) of one-year-old branches of peaches.

In this study, we conducted a low-temperature exothermic (LTE) investigation on 1-year-old (1a) branches of sixteen peach cultivars through a differential thermal analysis (DTA) procedure. We used a three-point approach to determine the lethal injury temperature (LT-I) of the xylem, the LTE correlation indexes, and the subordinate function value method were applied to compare cold hardiness of sixteen peach varieties. The results showed that the slope of the LT-I for the xylem of sixteen peach cultivars was different, and the LTE indexes were significantly different. Among all the studied varieties, the cold hardiness was strongest in Donghe No.1, followed by Wangjiazhuangmaotao No.2 and Hunchun. Qiuyan and Yanhong are second, and belong to the cold-resistant type; Qiuyi, Okubo, Zhongnongjinhui, and Chunmei, exhibited medium cold hardiness. Zhongtaohongyu, Spring snow, Yufei, and Zhongyou No.8 varieties exhibited low hardiness; while the 21st century, Golden Honey No. 1 and Zhonghuashoutao have the worst cold hardiness and are the weakest cold-hardiness types. In addition, the injury degrees of xylem from LT-I analysis were significantly related to the browning rates (BR) and electrolytic leakage (EI) from traditional low temperature freezing analysis. It is demonstrated that the LTE analysis is a simple, accurate, and practical method for identifying the cold hardiness of 1a branches of peach.

FEM education in undergraduate studies: Industry‐informed research

AbstractRecent mechanical engineering graduates are expected to utilize Finite Element Analysis (FEA) in structural and machine design activities. However, after decades of implementation in engineering schools, the Finite Element Method (FEM) still challenges instructors and course designers. To align learning outcomes with industrial requirements, this article analyzes the opinions of Mexican industrial and academic experts about four important aspects of FEM education. The results suggest that specialists agree on the importance of including a mixture of theoretical and applied topics in the syllabus but prefer practical skills over fundamental concepts. Besides learning from defeaturing to postprocessing a model, engineering students must know how to plan, verify, and validate their finite element studies. Experts expect early design engineers to be proficient with Computer‐Aided Design (CAD) and have relevant mathematical and programming skills. Instead of using specialized software, students' first exposure to FEM may be based on FEA tools embedded in CAD systems. Also, academic and industrial respondents request the incorporation of modal, thermal and nonlinear analysis procedures in the course timetable. Finally, the statistical analysis shows that the two types of respondents share one common vision about the importance of the aspects under study. The findings from this work are useful for the design of FEM‐related coursework and can be used to guide course instructors about the right balance of theory and practice, overall course contents, and the selection of the software utilized for the practical part of the program.

Fabrication of Copper(II)-Coated Magnetic Core-Shell Nanoparticles Fe3O4@SiO2: An Effective and Recoverable Catalyst for Reduction/Degradation of Environmental Pollutants

In this work, we report the synthesis of a magnetically recoverable catalyst through immobilizing copper (II) over the Fe3O4@SiO2 nanoparticles (NPs) surface [Fe3O4@SiO2-L–Cu(II)] (L = pyridine-4-carbaldehyde thiosemicarbazide). Accordingly, synthesized catalysts were determined and characterized by energy dispersive X-ray spectrometry (EDS), X-ray diffraction (XRD), Fourier transforms infrared spectroscopy (FT-IR), vibrating sample magnetometer (VSM), field emission scanning electron microscopy (FESEM), and thermogravimetric-differential thermal analysis (TG-DTA) procedures. The [Fe3O4@SiO2-L–Cu(II)] was used for the reduction of Cr(VI), 4-nitrophenol (4-NP) and organic dyes such as Congo Red (CR) and methylene blue (MB) in aqueous media. Catalytic performance studies showed that the [Fe3O4@SiO2–L–Cu(II)] has excellent activity toward reduction reactions under mild conditions. Remarkable attributes of this method are high efficiency, removal of a homogeneous catalyst, easy recovery from the reaction mixture, and uncomplicated route. The amount of activity in this catalytic system was almost constant after several stages of recovery and reuse. The results show that the catalyst was easily separated and retained 83% of its efficiency after five cycles without considerable loss of activity and stability.

Numerical procedure for electro-thermal anti-icing system simulation coupling internal thermal analysis and external multi-physic code

The present work has the aim of coupling two codes, one able to perform icing simulations and another one capable to simulate the performance of an electro-thermal anti-icing system in an integrated fashion. In fact, the classical tool chain of icing simulation (aerodynamics, water catch and impact, mass and energy surface balance) is coupled to the thermal analysis through the surface substrate and the ice thickness. In general, the substrate consists of a multi-layered composite with different properties for each layer and embedded heaters (resistors) at interfaces between layers. In the present approach, the ice protection simulation is not decoupled from the ice accretion simulation, but a single computational workflow is considered. Validation results obtained on benchmark test cases from NASA database will be detailed as well as comparison with numerical results from other authors.

A Numerical and Experimental Analysis of Inconel 625 Electron-Beam Welding – Thermal Aspects

Inconel 625, a nickel based superalloy, finds application in many fields. It is known to have a good weldability and it is often used in the as-welded conditions, heat treatments could be necessary to relief stresses. Numerous variables are known to affect the residual stresses field: welding process, joined geometry and clamping conditions. Since experimental measurements based on X-ray diffraction are not straightforward, expensive experimental work could be substituted by numerical simulation. Before performing an elastoplastic simulation, thermal analysis results are needed, first.This paper focus on the thermal analysis procedure. The analysis has been validated by means of macrographs and with thermocouples data. The heat source was successfully modelled using a superimposition of a spherical and a conical shape heat source with Gaussian power density distribution in order to reproduce the nail shape of the fusion zone. Heat source parameters were chosen so that the model would match with experimentally determined weld pool shape and temperatures. Preliminary results of the metallurgical analysis are also presented.

New tools for carbohydrate sulfation analysis: heparan sulfate 2-O-sulfotransferase (HS2ST) is a target for small-molecule protein kinase inhibitors.

Sulfation of carbohydrate residues occurs on a variety of glycans destined for secretion, and this modification is essential for efficient matrix-based signal transduction. Heparan sulfate (HS) glycosaminoglycans control physiological functions ranging from blood coagulation to cell proliferation. HS biosynthesis involves membrane-bound Golgi sulfotransferases, including HS 2-O-sulfotransferase (HS2ST), which transfers sulfate from the cofactor PAPS (3′-phosphoadenosine 5′-phosphosulfate) to the 2-O position of α-l-iduronate in the maturing polysaccharide chain. The current lack of simple non-radioactive enzyme assays that can be used to quantify the levels of carbohydrate sulfation hampers kinetic analysis of this process and the discovery of HS2ST inhibitors. In the present paper, we describe a new procedure for thermal shift analysis of purified HS2ST. Using this approach, we quantify HS2ST-catalysed oligosaccharide sulfation using a novel synthetic fluorescent substrate and screen the Published Kinase Inhibitor Set, to evaluate compounds that inhibit catalysis. We report the susceptibility of HS2ST to a variety of cell-permeable compounds in vitro, including polyanionic polar molecules, the protein kinase inhibitor rottlerin and oxindole-based RAF kinase inhibitors. In a related study, published back-to-back with the present study, we demonstrated that tyrosyl protein sulfotranferases are also inhibited by a variety of protein kinase inhibitors. We propose that appropriately validated small-molecule compounds could become new tools for rapid inhibition of glycan (and protein) sulfation in cells, and that protein kinase inhibitors might be repurposed or redesigned for the specific inhibition of HS2ST.

Inverse Thermal Analysis of Ti-6Al-4V Laser Welds Using Solidification and Heat-Affected Zone Boundaries

Temperature histories of Ti-6Al-4V laser welds are presented, which are calculated using numerical-analytical basis functions and boundary constraints based on measured solidification and heat-affected zone cross sections. These weld temperature histories can be adopted as input data to various types of computational procedures, which include numerical models for prediction of solid-state phase transformations and mechanical response. In addition, these temperature histories can be used parametrically for inverse thermal analysis of welds corresponding to other welding processes whose process conditions are within similar regimes. The present study applies an inverse thermal analysis procedure that uses three-dimensional constraint conditions whose two-dimensional projections are mapped within transverse cross sections of experimentally measured solidification and heat-affected zone boundaries.

Temperature Histories of Structural Steel Welds Calculated Using Solidification-Boundary Constraints

Temperature histories of structural steel deep-penetration welds are presented, which are calculated using numerical-analytical basis functions and solidification-boundary constraints. These weld temperature histories can be adopted as input data to various types of computational procedures, which include numerical models for prediction of solid-state phase transformations and mechanical response. In addition, these temperature histories can be used parametrically for inverse thermal analysis of welds corresponding to other welding processes whose process conditions are within similar regimes. The present study applies an inverse thermal analysis procedure that uses three-dimensional constraint conditions whose two-dimensional projections are mapped within transverse cross sections of experimentally measured solidification boundaries. In addition, the present study uses experimentally measured estimates of the heat effect zone edge to examine the consistency of calculated temperature histories for steel welds.

Inverse Thermal Analysis of Steel Welds Using Solidification-Boundary Constraints

Inverse thermal analyses of structural steel deep-penetration welds are presented. These analyses employ a methodology that is in terms of numerical-analytical basis functions and constraint conditions for inverse thermal analysis of steady-state energy deposition in plate structures. These analyses provide parametric representations of weld temperature histories that can be adopted as input data to various types of computational procedures, such as those for prediction of solid-state phase transformations and mechanical response. In addition, these parameterized temperature histories can be used for inverse thermal analysis of welds corresponding to other welding processes whose process conditions are within similar regimes. The present study applies an inverse thermal analysis procedure that uses three-dimensional constraint conditions whose two-dimensional projections are mapped within transverse cross sections of experimentally measured solidification boundaries.

Inverse Thermal Analysis of Welds Using Multiple Constraints and Relaxed Parameter Optimization

Aspects of a methodology for inverse thermal analysis of welds are examined that provide for relaxed model-parameter optimization. These aspects are associated with the inherent insensitivity of temperature fields, obtained by inverse analysis, to local shape variations of constrained boundaries within these fields. The inverse analysis methodology is in terms of numerical-analytical basis functions for construction parametric temperature histories, which can be adopted as input data to computational procedures for further analysis. In addition, these parametric temperature histories can be used for inverse thermal analysis of welds corresponding to other process parameters or welding processes whose process conditions are within similar regimes. The inverse thermal analysis procedure provides for the inclusion of volumetric constraint conditions whose two-dimensional projections are mappings onto transverse cross sections of experimentally measured boundary conditions, such as solidification and transformation boundaries, and isothermal surfaces associated with thermocouple measurements. Issues concerning relaxed parameter optimization are discussed with respect to inverse thermal analysis of Ti-6Al-4V pulsed-mode laser welds using multiple constraint conditions.

Thermal analysis and adiabatic calorimetry for early-age concrete members

This paper describes a procedure for thermal analysis on early-age concrete structures with experimentally obtained concrete adiabatic temperature rise and interface conductance between steel formwork and concrete. During hydration, concrete is considered in the analysis as non-homogeneous and the degree of hydration is dependent on both thermal loading and thermal properties development. A thermal convection model was implemented to simulate the external heat loss. Experimentally, two 1.2-m concrete cubes were constructed with embedded temperature sensors. The measured temperature time histories correlate well with the calculated values using a finite element model developed for this study. The modeling method and the experimental procedures developed are able to accurately predict the temperature evolution within an early-age concrete structure.

Inverse Thermal Analysis of Titanium GTA Welds Using Multiple Constraints

Inverse thermal analysis of titanium gas-tungsten-arc welds using multiple constraint conditions is presented. This analysis employs a methodology that is in terms of numerical-analytical basis functions for inverse thermal analysis of steady-state energy deposition in plate structures. The results of this type of analysis provide parametric representations of weld temperature histories that can be adopted as input data to various types of computational procedures, such as those for prediction of solid-state phase transformations. In addition, these temperature histories can be used to construct parametric function representations for inverse thermal analysis of welds corresponding to other process parameters or welding processes whose process conditions are within similar regimes. The present study applies an inverse thermal analysis procedure that provides for the inclusion of constraint conditions associated with both solidification and phase transformation boundaries.

Fatigue limit evaluation of various martensitic stainless steels with new robust thermographic data analysis

Thermography represents an important tool to study fatigue behaviour of materials.In this work, the fatigue limit of martensitic and precipitation hardening stainless steels has been determined with thermographic methods. Despite their use in corrosive and cryogenic environments, there is a data lack in literature concerning the study of fatigue behaviour.The peculiarity of these materials is the brittle behaviour: therefore, during fatigue tests the characteristic small deformations determine small changes of temperature. Thus, to properly determine the fatigue limit of aforementioned stainless steels, a more accurate setup is necessary in order to correctly detect surface temperature of specimens due to dissipation heat sources.In literature, different procedures have already been proposed to evaluate the fatigue limit from thermal data but very few works lead to an early detection of dissipation process which can obtain a further reduction of overall testing time. The aim of the paper is to propose a new robust thermal data analysis procedure for estimating fatigue limit of stainless steels in automatable way.

Inverse Thermal Analysis of Ti-6Al-4V Deep-Penetration Welds Using Volumetric Constraints

Case study inverse thermal analyses of Ti-6Al-4V deep-penetration welds are presented. These analyses employ a methodology that is in terms of numerical-analytical basis functions for inverse thermal analysis of steady state energy deposition in plate structures. The results of the case studies provide parametric representations of weld temperature histories that can be adopted as input data to various types of computational procedures, such as those for prediction of solid-state phase transformations. In addition, these temperature histories can be used to construct parametric-function representations for inverse thermal analysis of welds corresponding to other process parameters or welding processes whose process conditions are within similar regimes. The present study applies an inverse thermal analysis procedure that provides for the inclusion of volumetric constraint conditions whose two-dimensional projections are mappings onto transverse cross sections of experimentally measured solidification and transformation boundaries.

Inverse Thermal Analysis of Stainless Steel Deep-Penetration Welds Using Volumetric Constraints

Case-study inverse thermal analyses of 304L, 21Cr-6Ni-9Mn, and Grade EH-36 stainless steel deep-penetration welds are presented. These analyses employ a methodology that is in terms of numerical-analytical basis functions for inverse thermal analysis of steady-state energy deposition in plate structures. The results of the case studies presented provide parametric representations of weld temperature histories that can be adopted as input data to various types of computational procedures, such as those for prediction of solid-state phase transformations. In addition, these temperature histories can be used to construct parametric-function representations for inverse thermal analysis of welds corresponding to other process parameters or welding processes whose process conditions are within similar regimes. The present study extends an inverse thermal analysis procedure applied in previous studies. This extension provides for the inclusion of volumetric constraint conditions whose two-dimensional projections are mappings onto transverse cross sections of experimentally measured solidification boundaries. This study also discusses specific aspects of the inverse-analysis methodology relevant to further development of algorithms for its application in practice.

Inverse Thermal Analysis of a Titanium Laser Weld Using Multiple Constraint Conditions

Inverse thermal analysis of a titanium laser weld using multiple constraint conditions is presented. This analysis employs a methodology that is in terms of numerical-analytical basis functions for inverse thermal analysis of steady-state energy deposition in plate structures. The results of this type of analysis provide parametric representations of weld temperature histories that can be adopted as input data to various types of computational procedures, such as those for prediction of solid-state phase transformations. In addition, these temperature histories can be used to construct parametric-function representations for inverse thermal analysis of welds corresponding to other process parameters or welding processes whose process conditions are within similar regimes. The present study extends an inverse thermal analysis procedure applied in previous studies. This extension provides for the inclusion of constraint conditions associated with both solidification and phase transformation boundaries.

The Influence of Spalling on the Fire Resistance of RC Structures

A great many of experiments has shown that reinforced concrete (RC) structures suffered from spalling in fire. However, at present there are still no convincing spalling predicting models available due to the inhomogeneous nature and complicated thermo-hydro-mechanical interactions in concrete at elevated temperatures. In order to evaluate the fire resistance of RC structures which are subjected to concrete spalling, a thermal analysis procedure is developed which considers the effects of spalling on the growth of temperature in RC members. The predicted temperatures are then used to model the structural behaviour. The spalled portion of concrete is modelled as "void", which has no thermal and mechanical properties. A series of parametric studies carried out on RC structural members with different boundary conditions shows that the influence of spalling on fire resistance is very significant apart from the RC slabs subject to higher laterally restraint.

고유변형률 기반 등가하중법을 이용한 판의 용접변형 해석

IIn this study, used is the equivalent loading method based on the inherent strain to predict the welding deformation of panel members. Equivalent loads are computed from the inherent strain distribution around weld line, and then applied for the linear finite element analysis. Thermal deformation of panel members can be, of course, carried out through the rigorous thermal elasto-plastic analysis procedure but it is not practical in applying to predicting the welding deformation of large structures such as blocks found in a ship structure from view of computing time. The present equivalent load approach has been applied to flat plate model to verify the present approach, and to several curved plate models having the curvature in the welding direction to investigate the effect of the longitudinal curvature upon the weld-induced deformation. The results are compared with those by thermal elasto-plastic analysis. As far as the present results are concerned, it can be said that the present approach shows good agreement with the results by welding experiment and the rigorous thermal elasto-plastic analysis. The present approach has been also applied to predict the welding deformation of panel block as for application illustration to practical model.