Structural Analysis on the Riveted Hull of the Paddle Steamer Medway Queen

This paper presents modelling and Finite Element Analysis (FEA) simulation studies on the reconstruction of the historic Medway Queen riveted steel ship. The objective of this study is to assess the longitudinal stress in the hull plates of the Medway Queen (MQ) under various sea and load conditions. Detailed stress analysis in the localised riveted joint regions on the hull is also undertaken. A detailed three-dimensional (3D) digitised model is generated and the used to obtain the cross sectional steel profiles of the ship and their section properties. Finite element analysis with structural elements is used to assess shear stress and bending moments of the ship structure. The model predictions for longitudinal stresses in hull plates are combined with stress assessments for the individual rivet joints in different, judged to be most critical, locations along the ship’s length. The structural beam model is used to simulate the ship’s stress behaviour under hogging and sagging conditions with two different wave heights. Four sets of live loads are also added to the to the simulation cases. From the longitudinal bending moment and shear force of all sixteen simulations cases, twenty extreme locations are identified and average stress on rivets of joints closed to these locations are predicted. Stress values predicted are below the maximum permissible value of 100Nmm-2 specified by British standards BS153 and BS449. In addition, hull plate test samples with various thicknesses of plates connected with various diameter rivet joints are experimentally tested to assess independently the rivet joint strength and validate the failure criteria adopted in the modelling methodology. The test results have agreed favourably with the limits detailed in the standard

A numerical procedure for the optimization of IGBT module packaging

A numerical solution procedure for optimizing the thermal-mechanical reliability of an IGBT module has been described in this paper. The procedure is robust and it can handle both discrete and continuous decision variables in the design of IGBT packaging. An example has been given to demonstrate its application. The objective functions in this example are the accumulated plastic work density in solder joints of a simplified IGBT module that is subject to cyclic temperature cycling and the maximum junction temperature when the model is subject to a constant thermal loading. The thickness of the chip mount-down solder, thickness of the substrate solder joint, and the location of the chip are used as continuous decision variables. The material selection for the baseplate is treated as a discrete variable. The objective function values are calculated using Finite Element Analysis method

Applying model order reduction to the reliability prediction of power electronic module wire bond structure

Predicting the reliability of power electronics module wirebond structures requires accurate computer models to investigate the design space constraints in a computationally efficient manner. This paper details a model-order reduction (MOR) method to solve the governing equations for electro-thermal behaviour of wire-bond structures and a linear-damage rule and fatigue model to predict their wear-out behaviour. Various MOR methods are compared in terms of their accuracy and computational efficiency. Finite element calculations are used to validate the MOR predictions in terms of accuracy and solution times. The paper presents for the first time the significant benefits that MOR techniques can provide to reliability engineers for predicting the electro-thermal and fatigue behaviour of wirebonds in power modules. For the six MOR methods assessed, the Rational Krylov Algorithm (RKA) outperforms all other MOR methods in terms of accuracy and solution times, where it provides a solution 84 times faster than a full finite element solve

Smart manufacturing with Artificial Intelligence and digital twin: a brief review

Digital twin and artificial intelligence technologies have proliferated as crucial enablers for Industry 4.0. With a digital twin, companies can digitally test and validate a product before it exists in the real world. By digitally recreating the planned production process for real-world use, engineers can identify any potential process changes before they happen. This brief survey summarizes their general developments and the current state of AI integration in smart manufacturing and advanced robotics. This survey also covers industrial automation and emerging techniques, such as 3D printing

A multiphysics modeling and experimental analysis of pressure contacts in power electronics applications

This paper details a modeling and experimental assessment of the packaging process for a silicon carbide Schottky diode using pressure contacts. The work detailed in this paper is original, as it applies a combined electrothermomechanical modeling analysis to this packaging method supported by experimental validation. A key design objective for this packaging process is to identify suitable contact pad materials, heatsinks, and process variables such as clamping force to meet electrical, thermal, and reliability specifications. Molybdenum and aluminum graphite (ALG) have been identified as two suitable materials for the contact pads. Clamping forces ranging from 300 to 500 N and electric current ranging from 10 to 30 A have been investigated in terms of the resulting electrical and thermal contact resistances, temperatures, and stresses induced across the package. The performance of two heatsink designs with heat dissipation rates of 12893 and 4991 W/m2k has also been investigated. Both the modeling and initial experimental results detailed in this paper show that ALG provides better performance in terms of generating a lower average chip temperature. Both temperature and stress in the diode are predicted as a function of clamping force and load current. This will aid the packaging engineer to identify suitable process parameters to meet junction temperature requirements at different applied load currents

Thermal-mechanical analysis of a power module with parametric model order reduction

This paper presents parametric model order reduction (pMOR) by the Lagrange approach of matrix interpolation for the thermal-mechanical and reliability study of a power electronics module (PEM) with nonlinear behaviours. Most pre-vious research in model order reduction (MOR) studies reports thermal-mechanical simulations using a sequentially coupled method. In this research, a direct-coupled thermal-mechanical analysis, which simultaneously solves the thermal and structural governing equations, has been used to obtain thermal and defor-mation results. Furthermore, for pMOR, the linear approach of matrix interpolation is limited to linear changes between sampled-parametric points. Hence, a new way of interpolating system matrices using the Lagrange interpolation method has been adopted to implement the matrix interpolation efficiently. The parametric reduced-order model (pROM) solution by the Lagrange approach of matrix interpolation agrees well with the full-order model (FOM) and takes similar computational time as the linear (bi-linear) approach of matrix interpolation. pROM simulations offer up to 85.5 % reduction in computational time

Parametrising temperature dependent properties in thermal-mechanical analysis of power electronics modules using parametric Model Order Reduction

In this paper, a direct-coupled thermal-mechanical analysis of a Power Electronics Modules (PEM) using ANSYS-FEM (Finite Element Method) is integrated with a Parametric Model Order Reduction (pMOR) technique. Unlike most present studies on model order reduction, which perform the coupled thermal-mechanical analysis by sequential-coupled thermal-mechanical models, the direct-coupled thermal-mechanical approach deployed in this study solves the thermal and structural models simultaneously. Commonly, pMOR mainly focuses on parametrising model parameters (e.g., material properties, loads.) that are constants. In this investigation, a new approach to parametrise temperature-dependent properties using pMOR, such as the coefficient of thermal expansion (CTE) of the materials in PEM structures, has been demonstrated in the context of the reliability assessment of electronic modules. A two-dimensional finite element model of a PEM is developed and used to study the temperature-dependent CTE effects of the Aluminium (Al) alloy on the thermal-mechanical response of the system under thermal load. A Krylov subspace-based technique, PRIMA, has been used for the model order reduction and a linear approach of matrix interpolation for the parametrisation in the pMOR. The full-order state-space model has 30,612 degrees of freedom (DOFs), and the reduced model achieved by pMOR has just 8 DOFs. The simulation runs show that with this approach, a substantial reduction in computational time can be achieved, for this problem, by 81% between the full and the reduced order models. In modelling predictions, the pMOR-based solution has retained the accuracy of results. In this instance, the average difference in stress result, compared to the ANSYS-FEM model (FOM) solution, is only 0.43%

Design of additively manufactured heatsinks for power electronics thermal management using adjoint level-set topology optimization

This paper investigates the potential of using the Adjoint Level-set topological optimization approach for design of additively manufactured power electronics heat sinks. Additive manufacturing techniques are readily able to fabricate highly complex metal geometries. This capability could be translated into development of higher performance thermal management solutions if the design methodology to exploit this potential. This study attempts to investigate the ability of topology optimization to meet this requirement. This paper provides a brief review of the current state-of-the-art in the topological optimization field. An overview of the Adjoint Level-set method is presented along with details of the implemented framework. This framework is used to design power electronics heatsinks, considering a combination of materials and fluid flow rates. The analysis is multi-objective, simultaneously considering heat extraction and flow pressure difference. The heat flux into the heatsink is considered to be from two discrete heat fluxes representing active packages within the power module. The cooling channels developed by the topology optimization framework react to the position of the heat sources. Results demonstrating the capability for topological optimization to develop effective thermal management solution are presented. The primary conclusions for the study are that this is an area that is worth of further investigation. Significant challenges need to be addressed, particularly relating to the rapid increase in computational cost as flow rates increase, before this technology can be transitioned to commercial adoptio

Coupled thermal-mechanical analysis of power electronic modules with finite element method and parametric model order reduction

This work presents a new approach for performing a parametric study and examining nonlinear material behaviours of a coupled thermal-mechanical model of a Power Electronics Module (PEM) by integrating the Finite Element Method (ANSYS-FEM) with Parametric Model Order Reduction (pMOR). The considered coupling method solves the thermal and structural models concurrently compared to the widely practised sequential coupling method. Instead of constant parameter values, which are generally regarded for pMOR studies, the temperature dependent material properties of the wire material have been parametrised in the work using the pMOR method. A generalised 2D model has been regarded here for thermal-mechanical analysis with the pMOR approach, parametrising temperature dependent coefficient of thermal expansion (CTE) and Young’s modulus (E) of the wire material to explore their impact on wire bonds. The matrix interpolation method has been applied here for the pMOR study, and PRIMA, a Krylov subspace-based model order reduction (MOR) technique, has been exercised for local model order reductions. A new efficient process based on the Lagrange interpolation technique has been developed to implement matrix interpolation in the parametric reduced order model (pROM). The reduced order models (ROM) have a degree of freedom (DOF) of just 8, compared to the full-order models’ (FOM) of 50, 602. The pROM provides an excellent solution and reduces computational time by 84% for the presented case

Evaluation of SiC Schottky diodes using pressure contacts

The thermomechanical reliability of SiC power devices and modules is increasingly becoming of interest especially for high power applications where power cycling performance is critical. Press-pack assemblies are a trusted and reliable packaging solution that has traditionally been used for high power thyristor- based applications in FACTS/HVDC, although press-pack IGBTs have become commercially available more recently. These press-pack IGBTs require anti-parallel PiN diodes for enabling reverse conduction capability. In these high power applications, paralleling chips for high current conduction capability is a requirement, hence, electrothermal stability during current sharing is critical. SiC Schottky diodes not only exhibit the advantages of wide bandgap technology compared to silicon PiN diodes, but they have significantly lower zero temperature coefficient (ZTC) meaning they are more electrothermally stable. The lower ZTC is due to the unipolar nature of SiC Schottky diodes as opposed to the bipolar nature of PiN diodes. This paper investigates the implementation and reliability of SiC Schottky diodes in press-pack assemblies. The impact of pressure loss on the electrothermal stability of parallel devices is investigated