In this paper, we study the energy absorption of metamaterials composed of unit cells whose special geometry makes the cross-sectional area and the volume of the bodies generated from them constant (for the same enclosing box dimensions). After a parametric description of such special geometries, we analyzed by finite element analysis the deformation of the metamaterials we have designed during compression. We 3D printed the designed metamaterials from plastic to subject them to real compression. The results of the finite element analysis were compared with the real compaction results. Then, for each test specimen, we plotted its compaction curve. By fitting a polynomial to the compaction curves and integrating it (area under the curve), the energy absorption of the samples can be obtained. As a result of these investigations, we drew a conclusion about the relationship between energy absorption and cell number.

Computer simulations are increasingly being used in the automotive industry to evaluate the state of stress in cylinder blocks during casting and heat treat processes. With recent advancements, it is now possible to model casting and quenching processes as well as residual stress and high cycle fatigue. However, calculating the final stress in cylinder blocks requires the integration of several software tools with different meshing topologies, numerical methods, data structures, and post-processing capabilities. The intent of this research is to develop an integrated virtual engineering environment that combines casting simulation, computational fluid dynamics, and finite element methods in order to simulate the manufacturing process from the beginning of casting, through water quenching heat treatment, to engine dynamometer testing. The computational environment is built on three CAE tools, Magmasoft, AVL Fire, and Abaqus, and required considerable amounts of research and development to validate each numerical method and the tools that facilitate data exchange between them.

The cooling history of carburized heat-treated gears plays a significant role in developing microstructure, hardness, and residual stress in the tooth that influences the fatigue performance of the gear. Evaluating gear carburizing heat treatment should include a microstructure and hardened depth evaluation. This can be done on an actual part or with a test piece. The best practice for a test piece is to use a section size that closely approximates the cooling rate at the gear flank of the actual gear. This study furthers work already presented showing the correct test piece size that should be used for different gear modules (tooth thicknesses). Metallurgical comparisons between test pieces, actual gears, and FEA simulations are shown.

This paper revisits a case study presented at Heat Treat 2009, investigating the failure of induction coils used for heat treating automotive wheel hubs. At the time, computer simulation was beginning to allow for virtual prototyping of heat treat applications as an alternative to experimental testing. As explained in the original paper on p. 86 of the 2009 HTS conference proceedings, although simulation helped in the development of a more robust coil, it was not used to pinpoint the cause of failure. In this current work, the authors tackle the same problem aided by more than a decade of improvements in compute power and finite element analysis techniques. To highlight the leaps made in virtual prototyping, the induction hardening coil previously analyzed using an axisymmetric 2D model is now examined using more precise 3D electromagnetic and thermal models while accounting for the rotation of the part.

This paper investigates the effect of various types of errors on the accuracy of finite-element models used to simulate electromagnetic induction heat treating processes. By comparing simulation outputs, it shows how FEA calculations are affected by incorrect material specifications, incorrectly entered data, imprecise data, misassigned elements, unsuitable mesh sizing, inadequate current or power, and failure to properly account for skin effect depth. The paper includes relevant data and equations in addition to computer generated plots.

This study demonstrates the use of simulation in the design of induction hardening coils. It compares three coil geometries, two of which leverage the flexibility of 3D printing. The paper explains how to set up and run the simulations in order to predict temperature fields, hardness profiles, and microstructure distributions in the workpiece. Based on the simulations, the conventionally manufactured coil and one of the two 3D-printed coils do not achieve the desired martensitic microstructure everywhere along the surface of the workpiece. In the case of the 3D-printed coil, the simulations show that the workpiece overheats in an area where its diameter abruptly changes. To fix the problem, the coil was adapted with an additional winding that carries current in the opposite direction. Simulations show that the redesign reduces hot spot temperature by more than 200 °C, producing the desired microstructure in that area of the workpiece and a more uniform hardness profile.

This paper presents a computational approach for assessing the potential for distortion when using high pressure gas to quench steel parts. It explains how to account for component geometry, heat transfer coefficient, gas temperature and velocity, heating and cooling rates, and phase transformations. The authors employ finite element modeling methods to determine local phase fraction and displacement in a Ferrium C64 disk for different quench pressures. Simulations at timed intervals show how distortion and phase fraction progress in different areas of the disk and along the edges of an off-center bore. The causes of distortion are examined and explained using the model, with insights into why the cooling rate has a nonlinear relation with distortion.

Press quenching is often used to harden parts that are sensitive to distortion, but it is a difficult process to control due to the effects of tooling and the relatively large number of process parameters. In this paper, the authors show how they use finite element analysis to optimize the process and tooling design for a spiral bevel gear made of carburized 9310 steel. Several designs adaptations are assessed, one of which is shown to minimize radial shrinkage and taper distortion in the inner diameter of the bore.

Although many have had success using CFD and FEA techniques to predict residual stress and distortion in water quenched aluminum alloys, there are still hurdles in using a computational approach to manage liquid quenching processes due to the lack of a quench severity database. Quench severity is defined by the Grossman number, which does not serve as a heat transfer model for CFD simulation because it omits much of the underlying physics. In this research, a new interpretation of quench severity makes it possible to separate the heat transfer model into two groups, one computable by CFD and one requiring calibration. The objective of this paper is to parameterize the boiling model by quenching conditions and validate the model using data obtained by quenchometer testing.

While the induction heating of non-ferrous alloys is fundamentally no different than that of other metals, the unique physical properties of different non-ferrous alloys have a number of critical induction heating implications. This paper addresses a number of physical characteristics and practical subtleties associated with the induction heating of non-ferrous alloys, focusing particularly on the influence of electromagnetic and thermal material properties. A mathematical optimization routine for continuous induction heating processes is also presented. Utilizing coupled electromagnetic-thermal FEA computer simulation results and taking into account real-world process requirements, this routine is used to maximize induction heating quality and equipment performance.

The inductors design process is the key point in the development of an induction heating machine to fulfil the customer specifications. Some special hardening profiles can be uniquely achieved using the induction heating technology. Different inductors shapes, flux concentrators, power supply frequencies and cooling media can be used to get the optimal thermal profile for the heat treatment. The possibility to study the design robustness of the process using virtual prototyping is the key to speed up the test-trials loop and to give a tool for a better understanding of the process. In the paper, a case study applied to a real industrial problem is presented. A batch of FEM (finite element method) simulations has been done to find the key parameters in the element positioning tolerances, the effect of the misalignment, and the influences of the part geometrical tolerances. Some additional simulation runs have been made to optimize the inductor shape, to stiffen the system and to achieve a more stable process. The method used is based on FEM taking into account the coupling between the electromagnetic and thermal fields, and the nonlinear behavior of the material properties.

Application of 3D finite element method (FEM) simulation for induction hardening of gears is still a time-consuming and expensive task. The significant cost of a simulation remains in the manual preparation of the 3D description of geometry. In the current work, we propose to complement the numeric simulations with automatic geometry generation based on a parametric representation of a gear and an induction coil. The parameters used to describe a gear are module, pitch diameter, and pressure angle. The circular coil is described by the height, external and internal diameters. FEM computations are implemented to solve magneto-quasi-static Maxwell’s equations. A demonstration of the possibilities of the proposed approach via a parametric study is presented by varying the module of a gear while keeping a constant number of teeth. A heuristic tuning of heating power frequency- time is presented here and compared to the classical semi-analytical equations and 2D simulations.

Electromagnetic induction has provided reliable, predictable, and cost-effective heat treatment results for decades. Recently-developed inverter technology, providing instantaneous and calculated frequency control during heating, is dramatically advancing the heat treatment quality and equipment capability that induction heat treatment systems can deliver. This paper presents the many advantages of the technology in numerous real-world induction heat treatment applications, particularly in the scan hardening of shafts and shaft-like components. Coupled electromagnetic-thermal finite element analysis simulation results are utilized throughout to graphically and numerically illustrate the revolutionary nature of this new technology.

In single-shot hardening applications, heat treated components often feature a variety of geometric complexities including variable wall thicknesses, sharp diameter transitions, lightening holes, slots, etc. Due to the inherent 3D electromagnetic nature of single-shot coils and the complex geometry components which they must accommodate, the design and optimization of single-shot hardening coils is typically a demanding and intricate task. This paper presents combined electromagnetic-thermal and thermal-mechanical FEA simulation results for the single-shot induction hardening of a power transmission shaft. The simulation results, including electromagnetic, thermal, metallurgical, and mechanical data demonstrate the value of computer simulation in the design and development of single-shot induction hardening systems.

The distortion behavior of carburized and fully heat treated Ni-Cr-Mo martensitic steel (S156) has been experimentally evaluated. Dimensional measurements of Navy C-ring distortion coupons during interrupted heat treatment process for parts manufactured from two forming routes, hot forging and machined from as received bar, was performed. Metallurgical analysis was carried out to attempt to relate the observed microstructural characteristics with measured process induced distortion. The carburization process was found to be the most severe in terms of inducing distortion. It was found that additional heat treatments during the process results in a larger final distortion. Machining parts from forgings results in higher distortions than that of those machined directly from as received bar due to the added thermal processing history. A finite element simulation of the carburization process for a C-ring coupon is presented.

A finite element (FE) method was used to determine the important heat treating process parameters that impact the residual stress and distortion in steel. The FE model combines a commercially available heat treatment software DANTE to the finite element analysis software ABAQUS. A thermomechanical FE model was developed to model the evolution of microstructure, the volumetric changes associated with the kinetics of martensitic phase transformation and the formation and distribution of residual stress during quenching of steel. Alternative quenching parameters such as different steel grades, quenching orientation, immersion speed, quenching agent, quenching temperature, austenitizing temperature and part geometry were ranked based on their impact. The main purpose of this paper is to provide processing guidelines to control residual stress and distortion.

Accurate simulation of phase transformation during quenching of steels requires comprehensive knowledge of thermal and physical properties of the material. In cases when reliable material data are not available they can be obtained by a two-stage inverse method proposed in the paper. It includes a Jominy test of a specimen with thermocouples. At the first stage, we obtain TTT diagrams by means of analyzing cooling curves for several regions of the specimen obtained from experimental results. The second stage includes correction of material thermo-physical properties, i.e. the thermal conductivity and specific heat for each phase as well as estimation of the latent heat for each phase transformation. Parameters fitting is carried out iteratively by comparing FEM simulation and experimental results. Varying of parameters is performed with evolutionary methods of multi-parameter optimization. The developed method is implemented in QForm commercial software.

Heat treatment response of a complex shaped cylindrical component with varying sections of thickness and length has been studied in a 15CDV6 bainitic steel. The effect of cooling rate at every location has been predicted using an FEM based simulation. The distortion associated with the experimental component was matched with the theoretical FEM based heat treatment model. The component distortion has been attributed to the strain associated with volume changes associated with thermal gradient and phase transformation at various locations. The heat flux on the surface was modelled to arrive at heat transfer by inverse technique. The study validates the definition of boundary conditions for such complex components.

During the liquid quenching process, there are three main phases between the solid and the liquid interface: film boiling where vapor blanket covers the entire solid structure, transition or nucleate boiling, and single phase convection. The type of the quenching media, the agitation, and the flow pattern of a quench tank have significant effect on the cooling behavior during these three phases, which will affect the cooling rate, phase transformation, stress evolution and shape change of the quenched components. In this paper, transient CFD analysis using AVL FIRE is coupled with heat treatment analysis using DANTE to simulate an oil quench hardening process of a test gear made of Pyrowear 53. The gear is carburized prior to quench hardening. During the coupling analyses, the heat flux between the gear and the oil calculated in the CFD model is applied to the solid heat treatment model, and the gear surface temperature predicted by the heat treatment model is passed back to the transient CFD model. The aforementioned CFD tool is capable of considering the entire quenching domains without considering phase transformations in the quenched components. In the present case the gear is treated with a finite element tool in combination with DANTE to account for the latent heat release, which slows down the cooling. The relations between carbon content, temperature field, phase transformation, internal stress, and shape change during quenching are explained from the heat treatment modeling results. The coupling of CFD and heat treatment analyses provides a more robust application of computer modeling in the heat treatment industry.

Air quenching is a common manufacturing process to produce high strength metal component by rapidly cooling heated parts in a short period of time. With the advancement of finite element analysis (FEA) methods, it has been possible to predict thermal residual stress by computer simulation. However, the accuracy of FEA calculation is bounded by the accuracy of the temperature data, acquired either by thermocouple measurement, experimentally calibrated heat transfer coefficient (HTC) method, or computational fluid dynamics (CFD) calculation. While CFD methods have gained popularity, the practicality of CFD method is reduced by tedious mesh generation and costly computation that is only feasible to be performed on a supercomputer. When quenching media is a gas-phased fluid and quenching flow is steady, the flow and temperature fields exhibit certain characteristics that could lead to the development of enhanced HTC method that is more computation efficient and yet produces more accurate temperature data.