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Computational approach for reliable and robust system-in-package design
A computational modelling approach integrated with optimisation and statistical methods that can aid the development of reliable and robust electronic packages and systems is presented. The design for reliability methodology is demonstrated for the design of a SiP structure. In this study the focus is on the procedure for representing the uncertainties in the package design parameters, their impact on reliability and robustness of the package design and how these can be included in the design optimisation modelling framework. The analysis of thermo-mechanical behaviour of the package is conducted using non-linear transient finite element simulations. Key system responses of interest, the fatigue life-time of the lead-free solder interconnects and warpage of the package, are predicted and used subsequently for design purposes. The design tasks are to identify the optimal SiP designs by varying several package input parameters so that the reliability and the robustness of the package are improved and in the same time specified performance criteria are also satisfie
Reliability based design optimisation for system-in-package
This paper discusses a reliability based optimisation modelling approach demonstrated for the design of a SiP structure integrated by stacking dies one upon the other. In this investigation the focus is on the strategy for handling the uncertainties in the package design inputs and their implementation into the design optimisation modelling framework. The analysis of fhermo-mechanical behaviour of the package is utilised to predict the fatigue life-time of the lead-free board level solder interconnects and warpage of the package under thermal cycling. The SiP characterisation is obtained through the exploitation of Reduced Order Models (ROM) constructed using high fidelity analysis and Design of Experiments (DoE) methods. The design task is to identify the optimal SiP design specification by varying several package input parameters so that a specified target reliability of the solder joints is achieved and in the same time design requirements and package performance criteria are me
Life-cycle of fatigue sensitive structures under uncertainty
Fatigue is the one of the main contributors to problems related to structural safety of civil and marine structures. Life-cycle management (LCM) techniques considering various uncertainties can be used to predict the safe service life of fatigue sensitive structures, plan for their future inspections and support the decision making process regarding maintenance and repair actions. This paper provides a brief overview of the LCM of fatigue sensitive civil and marine structures under uncertainty. Probabilistic performance prediction, inspection scheduling and maintenance optimization for such structures are discussed
A multi-objective framework for the optimisation of life-cycle costs of wind turbines
Peer reviewedPublisher PD
High-Dimensional Stochastic Design Optimization by Adaptive-Sparse Polynomial Dimensional Decomposition
This paper presents a novel adaptive-sparse polynomial dimensional
decomposition (PDD) method for stochastic design optimization of complex
systems. The method entails an adaptive-sparse PDD approximation of a
high-dimensional stochastic response for statistical moment and reliability
analyses; a novel integration of the adaptive-sparse PDD approximation and
score functions for estimating the first-order design sensitivities of the
statistical moments and failure probability; and standard gradient-based
optimization algorithms. New analytical formulae are presented for the design
sensitivities that are simultaneously determined along with the moments or the
failure probability. Numerical results stemming from mathematical functions
indicate that the new method provides more computationally efficient design
solutions than the existing methods. Finally, stochastic shape optimization of
a jet engine bracket with 79 variables was performed, demonstrating the power
of the new method to tackle practical engineering problems.Comment: 18 pages, 2 figures, to appear in Sparse Grids and
Applications--Stuttgart 2014, Lecture Notes in Computational Science and
Engineering 109, edited by J. Garcke and D. Pfl\"{u}ger, Springer
International Publishing, 201
Optimal Reliability for Components under Thermomechanical Cyclic Loading
We consider the existence of optimal shapes in the context of the
thermomechanical system of partial differential equations (PDE) using the
recent approach based on elliptic regularity theory. We give an extended and
improved definition of the set of admissible shapes based on a class of
sufficiently differentiable deformation maps applied to a baseline shape. The
obtained set of admissible shapes again allows one to prove a uniform Schauder
estimate for the elasticity PDE. In order to deal with thermal stress, a
related uniform Schauder estimate is also given for the heat equation. Special
emphasis is put on Robin boundary conditions, which are motivated from
convective heat transfer. It is shown that these thermal Schauder estimates can
serve as an input to the Schauder estimates for the elasticity equation. This
is needed to prove the compactness of the (suitably extended) solutions of the
entire PDE system in some state space that carries a c2-H\"older topology for
the temperature field and a C3-H\"older topology for the displacement. From
this one obtains he property of graph compactness, which is the essential tool
in an proof of the existence of optimal shapes. Due to the topologies employed,
the method works for objective functionals that depend on the displacement and
its derivatives up to third order and on the temperature field and its
derivatives up to second order. This general result in shape optimization is
then applied to the problem of optimal reliability, i.e. the problem of finding
shapes that have minimal failure probability under cyclic thermomechanical
loading.Comment: 32 pages 1 figur
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