Thermomechanical Approach Research Articles

Modelling and analysis of the impact of chatter and cutting forces on machined surfaces in milling

The Chatter vibrations are a critical issue in milling, affecting workpiece quality and potentially damaging machines. This study analyzes the causes of chatter and proposes preventive methods. After reviewing the existing research, the transfer function is analyzed using an orthogonal cutting model, highlighting its evolution concerning system stability. A dynamic stability map is developed to help select optimal spindle speeds and cutting depths. Experiments using an innovative chatter detection device, based on noise analysis, demonstrate real-time identification of chatter, enhancing operational stability. The second part focuses on modeling cutting forces, essential for optimizing machining conditions and mitigating vibrations. A thermo-mechanical approach is applied using the Abaqus simulator and the Arbitrary Lagrangian-Eulerian (ALE) method to study the impact of cutting conditions on mechanical stress and temperature at the tool-workpiece interface. The results show that cutting parameters significantly influence both stress distribution and thermal behavior. By combining real-time chatter detection with precise cutting force modeling, this study offers an effective way to optimize machining parameters, improving process stability and operational efficiency. This integrated approach enhances the accuracy of predictive models and contributes to better machining outcomes.

Modifying Cassava Starch via Extrusion with Phosphate, Erythorbate and Nitrite: Phosphorylation, Hydrolysis and Plasticization.

Extrusion processing of plasticized cassava starch, a prominent industrial crop, with chemical additives offers a thermo-mechanical approach to modify starch structures through physical and chemical interactions. This research investigates the interaction and morphology of thermoplastic cassava starch (TPS) blended with tetrasodium pyrophosphate (Na4P2O7), sodium tripolyphosphate (Na5P3O10), sodium hexametaphosphate (Na6(PO3)6), sodium erythorbate (C6H7O6Na), and sodium nitrite (NaNO2) via twin-screw extrusion. The effects of these additives on the chemical structure, thermal profile, water absorption, and solubility of the TPS were examined. The high temperature and shearing forces within the extruder disrupted hydrogen bonding at α-(1-4) and α-(1-6) glycosidic linkages within anhydroglucose units. Na4P2O7, Na5P3O10 and Na6(PO3)6 induced starch phosphorylation, while 1H NMR and ATR-FTIR analyses revealed that C6H7O6Na and NaNO2 caused starch hydrolysis. These additives hindered starch recrystallization, resulting in higher amorphous fractions that subsequently influenced the thermal properties and stability of the extruded TPS. Furthermore, the type and content of the added modifier influenced the water absorption and solubility of the TPS due to varying levels of interaction. These modified starch materials exhibited enhanced antimicrobial properties against Escherichia coli and Staphylococcus aureus in polyester blends fabricated via extrusion, with nitrite demonstrating the most potent antimicrobial efficacy. These findings suggest that starch modification via either phosphorylation or acid hydrolysis impacts the thermal properties, morphology, and hydrophilicity of extruded cassava TPS.

Towards an automated framework for numerical prediction of residual stresses and deformations in metal additive manufacturing

Metal additive manufacturing (AM) revolutionizes design with complex structures and customizable material properties. However, high-energy heat source utilized in metal AM creates non-uniform temperature gradients, which usually leads to significant residual stresses and deformations. The present study proposes a line source based semi-analytical thermo-mechanical approach. The accuracy of the proposed line source based model is thoroughly examined by comparing with corresponding experiments in the literature and other numerical models. Besides, an automated framework for fast construction of a thermo-mechanical FE model for the metal AM process is introduced. A numerical tool AM-builder is developed to bridge the gap between AM process parameters and the FE model. The proposed automated framework is followed by utilization of the AM-builder and the line source based model. A purely numerical example is conducted to demonstrate the effectiveness of the proposed automated framework in rapidly constructing AM thermo-mechanical models for various geometries.

High-quality recycled concrete aggregates developed through an integrated thermomechanical approach

This study demonstrates an integrated thermomechanical treatment process to produce high quality recycled concrete aggregate (RCA) for structural concrete. RCA is mechanically treated after 90 min of heating at 250 °C in this process. The material properties of RCA produced through 15 combinations of charges and drum revolutions are compared using a statistical method. The highest ranking of an RCA identifies it as a high-quality class. Concrete composed of 100% RCA (recycled aggregate concrete, RAC) has 1.7% higher compressive strength than natural aggregate concrete (NAC). RAC has tensile and flexural strengths of 0.95 and 1.03 in fraction of NAC. RAC meets durability criteria such as UPV greater than 4.4 km/s, rapid chloride ion penetration test (RCPT) less than 1000 C, electrical resistivity greater than 208 Ohm-m, and sorptivity closer to NAC. Water absorption and abrasion resistance are similar to or superior to those of NAC. Coherent and uniform surface morphology of RCA enhances the ITZ microstructure in RAC.

Surface tension of aqueous electrolyte solutions. A thermomechanical approach.

We determine the surface tension of aqueous electrolyte solutions in contact with non-polar dielectric media using a thermomechanical approach, which involves deriving the stress tensor from the thermodynamic potential of an inhomogeneous fluid. To obtain the surface tension, we calculate both the normal and tangential pressures using the components of the stress tensor, recently derived by us [Y. A. Budkov and P. E. Brandyshev, J. Chem. Phys. 159, 174103 (2023)] within the framework of Wang's variational field theory. Using this approach, we derive an analytical expression for the surface tension in the linear approximation. At low ionic concentrations, this expression represents the classical Onsager-Samaras limiting law. By utilizing only one fitting parameter, which is related to the affinity of anions to the dielectric boundary, we successfully approximated experimental data on the surface tension of several aqueous electrolyte solutions. This approximation applies to both the solution-air and solution-dodecane interfaces, covering a wide range of electrolyte concentrations.

Modeling the effect of processing parameters on temperature history in Directed Energy Deposition: an analytical and finite element approach

PurposeThe purpose of this paper is to assess the feasibility of analytical models, specifically the radial basis function method, Akbari–Ganji method and Gaussian method, in conjunction with the finite element method. The aim is to examine the impact of processing parameters on temperature history.Design/methodology/approachThrough analytical investigation and finite element simulation, this research examines the influence of processing parameters on temperature history. Simufact software with a thermomechanical approach was used for finite element simulation, while radial basis function, Akbari–Ganji and Gaussian methods were used for analytical modeling to solve the heat transfer differential equation.FindingsThe accuracy of both finite element and analytical methods was validated with about 90%. The findings revealed direct relationships between thermal conductivity (from 100 to 200), laser power (from 400 to 800 W), heat source depth (from 0.35 to 0.75) and power absorption coefficient (from 0.4 to 0.8). Increasing the values of these parameters led to higher temperature history. On the other hand, density (from 7,600 to 8,200), emission coefficient (from 0.5 to 0.7) and convective heat transfer (from 35 to 90) exhibited an inverse relationship with temperature history.Originality/valueThe application of analytical modeling, particularly the utilization of the Akbari–Ganji, radial basis functions and Gaussian methods, showcases an innovative approach to studying directed energy deposition. This analytical investigation offers an alternative to relying solely on experimental procedures, potentially saving time and resources in the optimization of DED processes.

A Review on the Adiabatic Shear Banding Mechanism in Metals and Alloys Considering Microstructural Characteristics, Morphology and Fracture

The current review work studies the adiabatic shear banding (ASB) mechanism in metals and alloys, focusing on its microstructural characteristics, dominant evolution mechanisms and final fracture. An ASB reflects a thermomechanical deformation instability developed under high strain and strain rates, finally leading to dynamic fracture. An ASB initially occurs under severe shear localization, followed by a significant rise in temperature due to high strain rate adiabatic conditions. That temperature increase activates thermal softening and mechanical degradation mechanisms, reacting to strain instability and facilitating micro-voiding, which, through its coalescence, results in cracking failure. This work aims to summarize and review the critical characteristics of an ASB’s microstructure and morphology, evolution mechanisms, the propensity of materials against an ASB and fracture mechanisms in order to highlight their stage-by-stage evolution and attribute them a more consecutive behavior rather than an uncontrollable one. In that way, this study focuses on underlining some ASB aspects that remain fuzzy, allowing for further research, such as research on the interaction between thermal and damage softening regarding their contribution to ASB evolution, the conversion of strain energy to internal heat, which proved to be material-dependent instead of constant, and the strain rate sensitivity effect, which also concerns whether the temperature rise reflects a precursor or a result of ASB. Except for conventional metals and alloys like steels (low carbon, stainless, maraging, armox, ultra-high-strength steels, etc.), titanium alloys, aluminum alloys, magnesium alloys, nickel superalloys, uranium alloys, zirconium alloys and pure copper, the ASB propensity of nanocrystalline and ultrafine-grained materials, metallic-laminated composites, bulk metallic glasses and high-entropy alloys is also evaluated. Finally, the need to develop a micro-/macroscopic coupling during the thermomechanical approach to the ASB phenomenon is pointed out, highlighting the interaction between microstructural softening mechanisms and macroscopic mechanical behavior during ASB evolution and fracture.

Mechanically induced temperature oscillations in the coupled thermo-elasticity analysis of articulated dynamical systems

This article discusses a new approach for predicting and quantifying mechanically induced temperature oscillations in the coupled thermo-elasticity analysis of articulated mechanical systems (AMS). In this approach, the constrained equations of motion are solved simultaneously with discrete temperature equations obtained by converting heat partial-differential equation to a set of first-order ordinary differential equations. Dependence of the temperature gradients and their spatial derivatives on the position gradients, spinning motion, and curvatures is discussed. The approach captures dependence of the temperature-oscillation frequencies on the mechanical-displacement frequencies. The temperature field can be selected to ensure continuity of the temperature gradients at the nodal points. To generalize the AMS coupled thermo-elasticity formulation and capture the effect of the boundary and motion constraints (BMC) on the thermal expansion, the proposed method is based on integrating thermodynamics and Lagrange-D’Alembert principles. The absolute nodal coordinate formulation (ANCF) is used to describe continuum displacement and obtain accurate description of the reference-configuration geometry and change of this geometry due to deformations. A thermal-analysis large-displacement formulation is used to allow converting heat energy to kinetic energy, ensuring stress-free thermal expansion in case of unconstrained uniform thermal expansion. Cholesky heat coordinates are used to define an identity coefficient matrix for the efficient solution of the discretized heat equations. The approach presented is applicable to the two different forms of the heat equation used in the literature; one form is explicit function of the stresses while the other form does not depend explicitly on the stresses. Because of the need for using ANCF finite elements to achieve a higher degree of continuity in the coupled thermomechanical approach introduced in this article, the concept of the ANCF mesh topology is discussed.

Mathematical Modeling of the Argon Arc Welding Process. Part 1. Thermomechanical Approach and Model Justification

Mathematical Modeling of the Argon Arc Welding Process. Part 1. Thermomechanical Approach and Model Justification

Controlled Nano Cu precipitation through age treatment: a method to enhance the biodegradation, mechanical, antimicrobial properties and biocompatibility of Fe-20Mn-3Cu alloys.

Iron-manganese (Fe-Mn) based degradable biomaterials have been proven as a suitable substitute to permanent internal fracture-fixation devices. However, lower degradation and bacterial infection are still major concerns. To overcome these limitations, in this work, we have incorporated copper (Cu) in Fe-Mn system. The objective is to produce Cu nano-precipitates and refined microstructure through suitable combination of cold-rolling and age-treatment, so that degradation is improved eventually. High resolution transmission electron microscope (TEM) and scanning transmission electron microscope (STEM) confirmed the Cu rich composition of the nano-precipitates. Number of precipitates increased as aging time increased. Three-dimensional visualization of Fe, Mn and Cu atomic distributions using atom probe tomography (APT), indicated that Cu precipitates were in 15-50 nm range. Large number of nano-precipitates along with lower dislocation density led to highest strength (1078 MPa) and ductility (37 %) for the 6-hr age-treated sample. On the other hand, nano-precipitates and refined microstructure resulted highest degradation for the 12 hr of age treated sample (0.091 mmpy). When E.Coli bacteria was cultured with the sample extract, significantly higher antibacterial efficacy was observed for the sample having higher nano-precipitates. Higher degradation rate did not cause cyto-toxicity, rather promoted statistically higher cell proliferation (1.5 times within 24 hr) in in vitro cell-material interaction studies. In vivo biocompatibility of the alloy containing large nano-precipitates was confirmed from higher new bone regeneration (60%) in rabbit femur model. Overall study suggested that the optimization of the thermo-mechanical processes can effectively tailor the Fe-Mn-Cu alloys for successful internal fracture fixation. STATEMENT OF SIGNIFICANCE: : In the present work, we have reported a noble thermo-mechanical approach to simultaneously achieve Cu nano-precipitates and grain refinement in Fe-20Mn-3Cu alloy. Significant reduction in bacterial growth was observed in the sample containing high Cu precipitation. This is extremely significant in the present context. Cu nano-precipitates and grain refinement improved the degradation rate. Highest yield strength was observed after 12 hours of age treatment (493 MPa). We have theoretically calculated various factors of yield strength. High degradation rate did not cause cytotoxicity, rather promoted cell viability. We have reported that the released Cu ion concentration in vivo was not only below toxic limit, but also helped in new bone regeneration.

Hetero-deformation induced strengthening, precipitation hardening, and metastability engineering in a novel maraging Fe68Ni10Mn10Co10Ti1.5Si0.5 medium entropy alloy

In the present study, the concept of maraging characteristics has been manipulated using a multistep thermo-mechanical approach involving isothermal aging and reversion treatments. Accordingly, a novel metastable maraging Fe68Ni10Mn10Co10Ti1.5Si0.5 (at%) medium entropy alloy has been designed and microstructurally engineered to achieve a heterogeneous medium entropy alloy decorated by (NiMn)3−xTix and ƞ-Ni3Ti nano-precipitates. Remarkably, the alloy exhibited an ultra-high yield strength of ∼1.3 GPa with a total elongation of ∼25.3% in the partially reversed sample, attributed to several aspects of microstructural heterogeneities, including the dual-phase microstructure, compositional gradient heterogeneity, and nano-precipitates. We proposed a prospective direction for the development of high-performance materials for structural applications through the microstructural engineering of Fe-based medium entropy alloy.

Surface Modification on Magnesium Alloys’ Hardness and Microstructure Using Friction Stir Processing – A Review

Low density of magnesium-based alloy is one potential as the lightest structural material for light weight-high strength applications for automotive and aerospace. Severe plastic deformation (SPD) together with thermomechanical processing are proved to be a successful method for attaining desired microstructural modifications through achieving fine and highly misoriented microstructures and creating various structures to the bulk properties of magnesium alloy. The material's deformation can result in an altered microstructure that is gainful to the material's requirements. However, the poor deformability of magnesium and its alloys limits the application of the thermomechanical approach. Controlling over temperature and deformation rate is hard to achieve. Among the thermomechanical processes, friction stir processing (FSP) offers an easy way to achieve process stability and mechanical properties enhancement by heat treatment which results in the closure of porosity and refined grain size. During this process, heat is generated by the rotation of the FSP processing tool. Few process parameters such as rotational and traverse speeds should be controlled to make FSP stay within the defined processing condition. It is critical to set the right tool rotational speed as well as traverse speed to ensure adequate heat generation. As there are no established standards for operating the FSP, the only solution is to experiment with different settings to find the best parameter which will produce better quality on processed magnesium alloy workpiece. This paper explores earlier studies on surface modification via FSP technique to improve the mechanical properties strengthening of magnesium alloy mainly on grain size and hardness. The surface modification was done mostly on popular series of magnesium alloy (AZ series) using different tool material, tool geometry and different parameters combination. A comprehensive view of surface modification on magnesium alloys which includes the FSP tool and workpiece material used, variations of FSP parameters settings as well as the effect on hardness and microstructure analysis will be discussed.

Multi-scale Multi-physics Phase-field coupled Thermo-mechanical approach for modeling of powder bed fusion process

The present study investigates the thermomechanical simulation of powder bed fusion (PBF) process, focusing on the characterization of the melt pool. With the aim of comprehensively understanding the complex multi-physics phenomena inherent to the PBF process, our objective is to establish a robust and refined computational framework that is capable of systematic evaluation of the dynamic evolution of the melt pool geometry and temporal characteristics across the various stages of its formation. For this purpose, the Allen-Cahn phase field formulation is integrated with the elastoplastic material model based on J2 plasticity theory and the model implementation is conducted based on a finite element method (FEM) framework using the Multi-physics Object-Oriented Simulation Environment (MOOSE). As an objective, the model tends to depict the intricate, nonlinear, and non-equilibrium nature of the melt pool, encompassing multi-physics process of the PBF, while assuming powder particles as a homogenized continuum medium and neglecting complex interactions between the particles and their surroundings. This includes the separation of geometry into two domains (i) the powder layer and (ii) the substrate, the melting and solidification of the material, the phase-changing process, and the resulting induced distortion and residual stresses. Additionally, the model incorporates a phase indicator to account for the degree of solidification or consolidation of powder, whose evolution describes diffusion, solidification and shrinkage phenomena. This approach enables the tracking of the movement of the melting front of the metallic material induced by a heat source, effectively dividing the domain into regions of soft and hard solid states with a diffusive interface in between. Furthermore, to enhance the model's fidelity, an adaptive mesh refinement (AMR) strategy is employed to precisely capture important aspects of the phase changing process, such as characteristics of the solidification front and powder melting. To assess the model's performance, it is tested by simulating the processing of a three-dimensional Inconel 625 thin plate, as well as a benchmark example, where the influence of parameters such as temperature and phase change on the mechanical response of the system during the solidification process is elucidated.

The effects of pressure and pressure routes on the microstructural evolution and mechanical properties of sintered copper via SPS

Spark Plasma Sintering (SPS) is a pressure-assisted sintering process in which high density and mechanical properties are usually reached. This study applied the SPS to consolidate copper powder using different sintering pressures and pressure routes during holding time or heating. In the first route, the pressure was maintained (around 15 MPa) during the heating up to the sintering temperature (650 ºC), and the pressure was increased during the holding time. In the second route, the pressure was raised during the heating and kept constant during holding time at 650 ºC. Three different pressure levels were applied on each route: 110, 65, and 50 MPa. Microstructural evolution was investigated using densification (Archimedes method), scanning electron microscopy (SEM), hardness, and X-ray diffraction (XRD). The increase in pressure improves the microstructural features. In addition, in the first route, in which higher pressure rates were found, grain growth inhibition was observed, and densification was also improved significantly. The smallest crystallite size and highest microstrain were also observed at higher pressures. The increase in pressure also led to a rise in microhardness (17%), a decrease in pore volume fraction (10.5%), and an increase in pore circularity, causing substantial variations between the microstructures of samples. A finite element method (FEM) analysis was conducted using a thermo-mechanical approach to evaluate the stress distribution in the two different sintering routes. The results agree with the experimental results, and more pronounced effects were found in the first route because of higher compressive stresses, corroborating the results of microstrain and hardness.

Soft, strong, tough, and durable protein-based fiber hydrogels

Load-bearing soft tissues normally show J-shaped stress-strain behaviors with high compliance at low strains yet high strength at high strains. They have high water content but are still tough and durable. By contrast, naturally derived hydrogels are weak and brittle. Although hydrogels prepared from synthetic polymers can be strong and tough, they do not have the desired bioactivity for emerging biomedical applications. Here, we present a thermomechanical approach to replicate the combinational properties of soft tissues in protein-based photocrosslinkable hydrogels. As a demonstration, we create a gelatin methacryloyl fiber hydrogel with soft tissue-like mechanical properties, such as low Young's modulus (0.1 to 0.3 MPa), high strength (1.1 ± 0.2 MPa), high toughness (9,100 ± 2,200 J/m3), and high fatigue resistance (2,300 ± 500 J/m2). This hydrogel also resembles the biochemical and architectural properties of native extracellular matrix, which enables a fast formation of 3D interconnected cell meshwork inside hydrogels. The fiber architecture also regulates cellular mechanoresponse and supports cell remodeling inside hydrogels. The integration of tissue-like mechanical properties and bioactivity is highly desirable for the next-generation biomaterials and could advance emerging fields such as tissue engineering and regenerative medicine.

Downscaling for disc-brake wear testing using a thermomechanical approach

Brake wear has been identified to be an important source of non-exhaust emissions in transportation. The high dissipated energy in the contact not only results in large frictional heat dissipation in the brake components but also in the generation of debris, particles and gases produced by the wear of both pads and disc. Numerical simulation or tribological tests at the material scale are still not sufficient to predict wear. Experiments at the original scale of the brake system are necessary, with a significant implementation time, high costs and with a limited scope. The aim of the present work is a downscaling strategy to design experiments at reduced scale (i.e. pin-on-disc tribometer scale) taking care of the thermomechanical characteristics of the full-scale braking situation in the case of a railway application. This approach requires a complete understanding of the thermomechanical processes occurring during braking, with respect to the contact loading, the thermal localizations (migrating hot bands), the kinematics of contact opening and closing, and the couplings with the tribological circuit and the wear processes. Their apprehension is based on tests carried out on a full-scale bench equipped with the studied railway brake. A numerical model has been developed to interpret the experiment with respect to the kinetics of contact location and opening-closing, and to identify the relative determinants, key to wear. The transposition of the brake configuration to the tribometer configuration is based on these determinants in the design of a wear-preserving tribosystem. For example, the design of the disc has been adjusted on the reduced scale pin-on-disc system to fit with the kinetical parameters of contact location previously described related to the wear determinants.

Разработка модели для оценки напряженно-деформированного состояния твердосплавного инструмента при восстановительной обработке железнодорожных колес

The tense state of carbide instrument at turning treatment of railway wheels work is tested using mathematical modeling and Michel method, taking into account the thermomechanical approach and temperatures and forces effect on wear and plastic deformation of hard alloys

Исследование напряженного состояния твердосплавного инструмента при токарной обработке железнодорожных колес

Purpose: Investigation of the tense state of carbide cutting instrument at turning treatment of railway wheels. Methods: Influence of temperatures and forces on wear and plastic deformation of hard alloy is estimated using mathematical modeling and Mitchell methods as well as on thermomechanical approach basis. Results: The stress-strain state of cutting plates was evaluated and the analysis of wear shape was carried out which revealed that increase in wear chamfer occurs along back surface mainly in the vicinity of cutter tip. It is shown that shape stability temperature and tangential tensity are the factors affecting treatment conditions and wear rate of cutting plate. Practical significance: Dependences have been determined that allow assigning rational modes of treatment of railway wheel pairs during repairment.

Material Behaviour of Three Blade Propeller Using Metal Additive Manufacturing Techniques

The defects stored during the fusion of the laser with the metal powder bed determine the optimal performance of fatigue and lifelong disintegration of the formed metal components. The advantage of using recent technologies of prototyping is very much powerful in understanding the physical process. The current works provide the details of the same for a 3-blade propeller with its thermomechanical approach to identified parameters. The results provide the materials used and their behaviour with the parameters which conclude in prescribing the material for the various applications. The investigation aimed to optimize the position of the object (3-blade Propeller) and material for printing through simulation before it was printed. The material choices of aluminium AlSi10 Mg, stainless steel 17–4 and stainless steel 316L were considered. The ten different object positions were considered and ranked by the minimum support area required. The top and bottom-ranked positions were further investigated with three different materials, namely Aluminium AlSi10 Mg, atainless steel 17–4, and stainless steel 316L, in which the Rank 1 position, the material of Aluminium AlSi10 Mg exhibits the minimum of maximum displacement (2.348e-01 mm), plastic strain (0.05), and the Von Mises Stress (2.086e+02 MPa).

Thermo-mechanical approach to study the residual stress evolution in part-scale component during laser additive manufacturing of alloy 718

Laser Additive Manufacturing (LAM) is a promising technology for manufacturing gas turbine components with enhanced design capability and a significant reduction in part weight. Additive manufacturing of alloy 718 using Laser Powder Bed fusion (L-PBF) process poses certain challenges pertaining to complex residual stress, micro-segregation of Nb, and undesired Laves phase formation in the as-printed state. The built-up residual stress and undesired brittle phase may lead to cracks and build failures. This article studied residual stress evolution during L-PBF of alloy 718 using Finite Element (FE) thermo-mechanical simulation implemented in Simufact Additive® software. The model adopted the bundling of physical powder in voxel mesh to minimize the computational time and mimic the actual process scenario during part-scale simulation. Experimental flow curves generated from Gleeble 3800® tests at elevated temperatures were utilized to calibrate material property for better accuracy in the FE simulation. The calibrated model was used to study the residual stress evolution during support structure removal. Verification and validation of simulated results were performed using X-ray diffraction (XRD) measurements. The simulated value agrees well with the experimental value with a maximum deviation of 7%. Finally, the experimentally validated model was used to correlate the effect of layer thickness variation on residual stress evolution.