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Multidisciplinary Methods For Analysis Optimization Control Complex Systems

As a base concept in the first stage we use some simple, fast, rapidly converging algorithm, then some finer grade algorithm like population based swarm optimization method. In this paper, we will show and evaluate some multi-level optimization methods tested on several test functions, comparing the convergence and computational needs.

Structural sizing optimization at Airbus leans on different approaches depending on the needs. Two main solutions have been defined, mainly for questions of performance and deployment.

A rapid solution PRESTO has been developed based on a pure discrete algorithm to perform parametric trade-off studies in early design stages. The structure optimization process has been simplified in such a way that it is as quick as possible.

Multidisciplinary Methods for Analysis, Optimization and Control of Complex Systems

This is the right solution to be used by non-expert users in early overall aircraft studies. It exploits large databases and surrogate models in a Big Data mindset. It uses a standard continuous optimization approach based on gradient information and state of the art mathematical programming algorithms.

A second step allows performing a discrete ply-by-ply optimization for composite covers using an optimization heuristic ant colony paradigm. This is the right technology to address advanced structure optimization and to be included in MDO processes. Both methods are under integration in a single platform SOFIA to provide adequate sizing optimization services for the relevant components e. A status will be made in this paper on the technologies used in the different tools, the applications performed and the current and future research and development axes especially in the effort to merge solutions or to integrate them in multidisciplinary processes.

This paper presents a method to find the global solution of combined truss-frame size optimization problems. The approach is based on a reformulation of the optimization problem as a Mixed-Integer Linear Programming problem MILP which is solved by means of a branch-and-bound method. A portal frame that consists of both beam and truss elements is adopted as a test case.

6. Design Definition and Multidisciplinary Optimization

The optimal sections of the portal frame have to be selected from a square hollow sections catalog. The design of the portal frame has to meet the requirements prescribed by the Eurocodes. These requirements are adopted as constraints by reformulating them as or approximating them by a linear equation. Not only the Eurocode constraints related to member strength and stability but also all Eurocode constraints related to the joints of the structure are taken into account during the optimization. As a consequence, a post-processing step to account for other constraints is avoided, therefore optimality is retained and additional engineering time is reduced.

The optimization results are presented and the influence of the joint constraints on the optimal design is discussed. In addition, the efficiency of the method is compared with the efficiency of a genetic algorithm. Heat exchangers are used in industrial and household processes to recover heat between two process fluids.

This paper shows numerical investigations on heat transfer in a double pipe heat exchanger. The working fluids are water, and the inner and outer tube was made from carbon steel. There are several constructions which able to transfer the requested heat, but there is only one geometry which has the lowest cost. This cost comes from the material cost, the fabrication cost and the operation cost.

These costs depend on the material types and different geometric sizes, for example inner pipe diameter, outer pipe diameter, length of the tube. The performance of the heat exchanger and the pressure drop are in a close interaction with the geometry.

  1. 1. Introduction.
  2. Multidisciplinary Methods For Analysis Optimization Control Complex Systems – Free Online Books!
  3. The metamorphosis of plants;
  4. SIAM Journal on Optimization!
  5. Advances in Structural and Multidisciplinary Optimization.

Optimum sizes can be calculated from the initial conditions when one of the process fluid inlet and outlet temperature and the flow rate is specified. The correlations to the Nusselt number and the friction data come from experimental studies. We present here a topology optimization method based on a homogenization approach to design oriented and parametrized cellular structures. The present work deals with 2-D square cells featuring a rectangular hole, because their structure is close to that of rank-2 sequential laminates, which are optimal for compliance optimization.

For several cells, the value and the parametric sensitivities of their effective elastic tensor can easily be computed, by the resolution of a cell problem. The obtained results can be used to build a surrogate model for the homogenized constitutive law. Moreover, we add the local orientation of the cells to our problem.

Then, an optimal composite shape is computed thanks to an alternate directions algorithm. The crucial ingredient of the methodology is the extraction of a quasi-periodic and additive manufacturable structure from the previously obtained composite shape, based on the introduction of a space transformation. In order to improve the ability of a large-scale light-weight composite structure to carry tensile or compressive loads, stiffeners are added to the structure.

The stiffeners divide the structure into several smaller panels. For a composite structure to be manufacturable, it is necessary that plies are continuous in multiple adjacent panels.

Advances in Structural and Multidisciplinary Optimization |

To be able to prescribe a manufacturable design, an optimization algorithm can be coupled with a reference table for the stacking sequences SST. As long as the ply stacks are selected from the SST, it is guaranteed that the design is manufacturable and all strength related guidelines associated with the design of composite structures are satisfied.

An SST is made only based on strength related guidelines. Therefore, there exist a large number of possibilities for SSTs. Minimized mass is a typical goal in the design of aircraft structures. Different SSTs result in different values for the minimized mass. Thus it is crucial to perform optimization based on the SST which results in the lowest mass.

This paper aims to introduce an approach to generate a unique SST resulting in the lowest mass. The proposed method is applied to the optimization problem of a stiffened composite structure resembling the skin of an aircraft wing box. Composite materials offer the possibility to design tailored laminates for a broad spectrum of applications such as airplane wings or monocoques in the automotive industry.

Especially when carbon fiber reinforced plastic is used, parts with enormous performance can be designed. The downside of designing a laminate is the complexity of the task itself, as well as the price of the carbon fiber. Placing the expensive carbon fiber only at the necessary positions can help to reduce the costs of the parts and to increase the performance, specifically the stiffness, compared to a glass fiber laminate itself.

Designing the laminate gets even harder, an algorithm is needed to support the engineer in this task. This paper will introduce a lean method using the principal stress line to locate the best position for carbon fiber patches using a Michell structure. The Michell structure is optimized for tensile and pressure forces.

Unidirectional tapes have outstanding properties in fiber direction, but weak performance orthogonal to the direction of the fiber. Placing the unidirectional tapes along the Michell structure will load the tapes in an optimal way. First of all the algorithm will determine the principal stress lines connecting load and bearing.

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These will be used as a starting point for a Michell structure. The generated Michell structure will be optimized to increase the performance. After the substructure is found, it will be mapped back into the original laminate. The new improved laminate will be compared with the original one, concerning weight, stiffness and pricing. A significant reduction in weight could be achieved at a constant price and improved stiffness.

Whilst structural design processes in engineering have been extensively developed, the additional consideration of uncertainty quantification UQ provides a more holistic forecast on its long term sustainability. UQ methods such as Polynomial Chaos Theory have received attention in numerous fields within engineering for its ability to approximate statistical moments with good accuracy and with low computational expense. This UQ method has not been explored thoroughly within the aerospace sector.

Baseline characteristics are compared to an approximation derived from RMT and the worst case scenarios. It was found that RMT provided a good estimate of both the frequency and magnitude shifts of the vibrational modes under the enforced uncertainty.