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The purpose of this paper is to investigate a simulation solution for estimating the residual stresses developed in metal fused filament fabrication (MF³) printed parts. Additionally, to verify these estimates, a coupled experimental–computational approach using the crack-compliance method was investigated in this study.

In this study, a previously validated thermomechanical process simulation was used to estimate the residual stresses developed in the MF³ printing process. Metal-filled polymer filament with a solids loading of 59 Vol.% Ti-6Al-4V was studied. For experimental validation of simulation predictions, the MF³ printed green parts were slitted incrementally and the corresponding strains were measured locally using strain gauges. The developed strain was modeled in finite-element-based structural simulations to estimate a compliance matrix that was combined with strain gauge measurements to calculate the residual stresses. Finally, the simulation results were compared with the experimental findings.

The simulation predictions were corroborated by the experimental results. Both results showed the same distribution pattern, that is, tensile stresses at the outer zone and compressive stresses in the interior. In the experiments, the residual stresses varied between 1.02 MPa (tension) and −2.28 MPa (compression), whereas the simulations were predicted between 1.37 MPa (tension) and −1.39 MPa (compression). Overall, there was a good quantitative agreement between the process simulation predictions and the experimental measurements, although there were some discrepancies. It was concluded that the thermomechanical process simulation was able to predict the residual stresses developed in MF³ printed parts. This validation enables the printing process simulation to be used for optimizing the part design and printing parameters to minimize the residual stresses.

The applicability of thermomechanical process simulation to predict residual stresses in MF³ printing is demonstrated. Additionally, a coupled experimental–computational approach using the crack-compliance method was used to experimentally determine residual stresses in the three-dimensional printed part to validate the simulation predictions. Moreover, this paper presents a methodology that can be used to predict and measure residual stresses in other additive manufacturing processes, in general, though MF³ was used as demonstrator in this work.

The purpose of this paper is to perform the computational fluid dynamics (CFD) simulation with experimental validation to investigate the particle segregation effect in abrupt and smooth shapes circulating fluidized bed (CFB) risers.

The experimental investigations were carried out in lab-scale CFB systems and the CFD simulations were performed by using commercial software BARRACUDA. Special attention was paid to investigate the gas-particle flow behavior at the top of the riser with three different superficial velocities, namely, 4, 6 and 7.7 m/s. Here, a CFD-based noble simulation approach called multi-phase particle in cell (MP-PIC) was used to investigate the effect of traditional drag models (Wen-Yu, Ergun, Wen-Yu-Ergun and Richardson-Davidson-Harrison) on particle flow characteristics in CFB riser.

Findings from the experimentations revealed that the increase in gas velocity leads to decrease the mixing index inside the riser. Moreover, the solid holdup found more in abrupt riser than smooth riser at the constant gas velocity. Despite the more experimental investigations, the findings with CFD simulations revealed that the MP-PIC approach, which was combined with different drag models could be more effective for the practical (industrial) design of CFB riser. Well agreement was found between the simulation and experimental outputs. The simulation work was compared with experimental data, which shows the good agreement (<4%).

The experimental and simulation study performed in this research study constitutes an easy-to-use with different drag coefficient. The proposed MP-PIC model is more effective for large particles fluidized bed, which can be helpful for further research on industrial gas-particle fluidized bed reactors. This study is expected to give throughout the analysis of CFB hydrodynamics with further exploration of overall fluidization.

This paper gives a review of the finite element techniques (FE) applied in the area of material processing. The latest trends in metal forming, non‐metal forming and powder metallurgy are briefly discussed. The range of applications of finite elements on the subjects is extremely wide and cannot be presented in a single paper; therefore the aim of the paper is to give FE users only an encyclopaedic view of the different possibilities that exist today in the various fields mentioned above. An appendix included at the end of the paper presents a bibliography on finite element applications in material processing for the last five years, and more than 1100 references are listed.

In line with the recent development of flip-chip reliability and underfill process, this paper aims to comprehensively investigate the effect of different hourglass shape solder joint on underfill encapsulation process by mean of experimental and numerical method.

Lattice Boltzmann method (LBM) numerical was used for the three-dimensional simulation of underfill process. The effects of ball grid arrays (BGA) encapsulation process in terms of filling time of the fluid were investigated. Experiments were then carried out to validate the simulation results.

Hourglass shape solder joint has shown the shortest filling time for underfill process compared to truncated sphere. The underfill flow obtained from both simulation and experimental results are found to be in good agreement for the BGA model studied. The findings have also shown that the filling time of Hourglass 2 with parabolic shape gives faster filling time compared to the Hourglass 1 with hemisphere angle due to bigger cross-sectional area of void between the solder joints.

This paper provides reliable insights to the effect of hourglass shape BGA on the encapsulation process that will benefit future development of BGA packages.

LBM numerical method was implemented in this research to study the flow behaviour of an encapsulation process in term of filling time of hourglass shape BGA. To date, no research has been found to simulate the hourglass shape BGA using LBM.

The development of robust control algorithms for the position, velocity and trajectory control of unmanned underwater vehicles (UUVs) depends on the accuracy of their mathematical models. Accuracy of the model is determined by precise estimation of the UUV hydrodynamic parameters. The purpose of this study is to determine the hydrodynamic forces and moments acting on an underwater vehicle with complex body geometry and moving at low speeds and to achieve the accurate coefficients associated with them.

A three-dimensional (3D) computer-aided design (CAD) model of UUV is designed with one-to-one dimensions. 3D fluid flow simulations are conducted using computational fluid dynamics (CFD) software programme in the solution of Navier Stokes equations for laminar and turbulent flow analysis. The coefficients depending on the hydrodynamic forces and moments are determined by the external flow analysis using the CFD programme. The Flow Simulation k-ε turbulence model is used for the transition from laminar flow to turbulent flow. Hydrodynamic properties such as lift and drag coefficients and roll and yaw moment coefficients are calculated. The parameters are compared with the coefficient values found by experimental methods.

Although the modular type UUV has a complex body geometry, the comparative results of the experiments and simulations confirm that the defined model parameters are accurate and close to the actual experimental values. In the proposed k-ε method, the percentage error in the estimation of drag and lifting coefficients is decreased to 4.2% and 8.39%, respectively.

The model coefficients determined in this study can be used in high-level control simulations which leads to the development of robust real-time controllers for complex-shaped modular UUVs.

The Lucky Fin UUV with 4 degrees of freedom is a specific design and its CAD model is first extracted. Verification of simulation results by experiments is generally less referenced in studies. However, it provides more precise parameter identification of the model. Proposed study offers a simple and low-cost experimental measurement method for verification of the hydrodynamic parameters. The extracted model and coefficients are worthwhile references for the analysis of modular type UUVs.

The purpose of this paper is to study the heat transfer effect of copper sensor and skin simulant on skin.

For the sensor, the physical and mathematical models of the thermal sensors were used to obtain the definite conditions in the heat transfer process of the sensor, and the heat transfer models of the two sensors were developed and solved respectively by using ANSYS WORKBENCH 19.0 software. The simulation results were compared with the experimental test results. For the skin, the numerical model of the skin model was developed and calculated. Finally, the heat transfer simulation performance of the two sensors was analyzed.

It is concluded that the copper sensor is more stable than the skin simulant, but the material and structure of the skin simulant is more suitable for skin simulation. The skin simulant better simulates the skin heat transfer. For all the factors in the model, the thermal properties of the material and the heat flux level are the key factors. The convective heat transfer coefficient, radiation heat transfer rate and the initial temperature have little influence on the results, which can be ignored.

The results show that there are still some differences between the experimental and numerical simulation values of the skin simulant. In the future, the thermal parameters of skin simulant and the influence of the thermocouple adhesion should be further examined during the calibration process.

The results suggest that the skin simulant needs to be further calibrated, especially for the thermal properties. The copper sensor on the flame manikin can be replaced by the skin simulant with higher accuracy, which will be helpful to improve the accuracy of performance evaluation of thermal protective clothing.

The application of computational fluid dynamics (CFD) technology can help to analyze the heat transfer simulation mechanism of thermal sensor, explore the influence of thermal performance of thermal sensor on skin simulation, provide basis for the development of thermal sensor and improve the application system of thermal sensor. Based on the current research status, this paper studies the internal heat transfer of the sensor through the numerical modeling of the copper sensor and skin simulant, so as to analyze the effect of the sensor simulating skin and the reasons for the difference.

In this paper, the sensor itself is numerically modeled and the heat transfer inside the sensor is studied.

The purpose of this study is to numerically simulate the Lamb wave propagation through a clamp-on ultrasonic gas flowmeter (UGF) in contact mode, using a new semi three-dimensional approach. Moreover, experimental and analytical modeling results for transit time difference method have been used to confirm the simulation results at different gas flow velocities from 0.3 to 2.4 m/s.

The new semi three-dimensional approach involves the simulation of the flow field of the gas in a three-dimensional model and subsequently the simulation of wave generation, propagation and reception in a two-dimensional (2D) model. Moreover, the analytical model assumes that the wave transitions occur in a 2D mode.

The new approach is a semi three-dimensional approach used in this work, has better accuracy than a complete 2D simulation while maintaining the computing time and costs approximately constant. It is faster and less expensive than a complete 3D simulation and more accurate than a complete 2D simulation. It was concluded that the new approach could be extended to simulate all types of ultrasonic gas and non-gas flowmeters, even under harsh conditions.

In this work, a new approach for the numerical simulation of all types of ultrasonic flowmeters is introduced. It was used for simulation of a Lamb wave ultrasonic flow meter in contact mode.

The purpose of this paper is to develop a finite element method (FEM) supported simulation of drilling process applied to superficially hardened steels and assess the heat treatments effect on the optimum drilling conditions (feed rate, speed, etc.).

A three-dimensional model was developed simulating the drilling procedure while experimental data, concerning the chip geometry and force components, were used to validate the model. The developed simulation will allow systematically insight on the tools wear progression induced by the developed temperature and stress fields. Two different cases of simulation were examined. A typical simulation was investigated, which erected with all the standard features found in the FEM simulation software. In the second case, all the experimental data were introduced.

The simulation results revealed that the advanced developed FEM model describes sufficiently the real chip geometry. Moreover, the FEM calculations provide an effective tool for predicting occurring temperatures, strain and stresses and thus for approaching the real loads of the cutting tool during drilling.

This paper fulfills an identified need to study the drilling simulation.

The purpose of this paper is to study the flexural behavior of additively manufacture Ultem 1010 parts. Fused deposition modeling (FDM) process has become one of most widely used additive manufacturing methods. The process provides the capability of fabricating complicated shapes through the extrusion of plastics onto a print surface in a layer-by-layer structure to build three-dimensional parts. The flexural behavior of FDM parts are critical for the evaluation and optimization of both material and process.

This study focuses on the performance of FDM solid and sparse-build Ultem 1010 specimens. Flexure tests (three-point bend) are performed on solid-build coupons with varying build orientation and raster angle. These parameters are investigated through a full-factorial design of experiments (DOE) to determine optimal build parameters. Air gap, raster width and contour width are held constant. A three-dimensional nonlinear finite element model is built to simulate the flexural behavior of the FDM parts.

Experimental results include flexure properties such as yield strength and modulus, as well as analysis of the effect of change in build parameters on material properties. The sparse-build FDM parts chosen from the experimental tests are simulated based on this developed model. Thermo-mechanical simulation results show that the finite element simulation and experimental tests are in good agreement. The simulation can be further extended to other complicated FDM parts.

From the DOE study, sparse-build coupons with specific build parameters are fabricated and tested for the validation of a finite element simulation.

This paper aims to present experimental and finite volume method (FVM)-based simulation studies on the scaling effect on the capillary contact angle and entrant pressure for a three-dimensional encapsulation process of ball-grid array (BGA).

With the development of various sizes of BGA packages, the scaling effect of BGA model on capillary underfill (CUF) process is investigated together with the influences of different industrial standard solder bump arrangements and dispensing methods used as case study.

The experimental results agree well to the simulation findings with minimal deviation in filling time and similar flow front profiles for all setups. The results revealed that the capillary contact angle of flow front decreases in scale-up model with larger gap height observed and lengthens the encapsulation process. Statistical correlation studies are conducted and accurate regression equations are obtained to relate the gap height to the completion filling time and contact angle. CUF threshold capillary pressures were computed based on Leverett-J function and found to be increasing with the scale size of the package.

These statistical data provide accurate insights into the impact of BGA’s scale sizes to the CUF process that will be benefiting the future design of BGA package. This study provided electronic designers with profound understanding on the scaling effect in CUF process of BGA, which may be extended to the future development of miniature-sized BGA and multi-stack device.

This study relates the flow behaviour of encapsulant to its capillary contact angle and Leverett-J pressure threshold, in the CUF process of different BGA and dispensing conditions. To date, no research has been found to predict the threshold pressure on the gap between the chip and substrate.