Veröffentlichungen

@inproceedings{Denkena2013,

title = {Efficient production of CFRP lightweight structures on the basis of manufacturing considerations at an early design stage},

author = {Berend Denkena and Peter Horst and Carsten Schmidt and Matthias Behr and Joscha Krieglsteiner},

year  = {2013},

date = {2013-09-18},

booktitle = {Machining Innovation Conference },

address = {Hannover},

abstract = {Success in development of lightweight structures is determined by the three disciplines of design, materials, and manufacturing. Focusing on design leads to expensive lightweight structures while overrating production makes it hard to reach structural performance goals. The global optimum of structural performance and cost can only be reached if all three disciplines are equally taken into account. It can be observed that this optimum gets increasingly important for major strategic decisions in lightweight construction industry, e.g. the material concept in future aircraft structures: carbon fiber-reinforced plastics (CFRP) vs. aluminum.



While development of metallic structures is industrially performed and broadly researched, fiber-reinforced plastics do present new challenges. Design work with homogeneous and isotropic metallic structures is mainly done on a level of part shape and sizing. For composites, the inner heterogeneous and orthotropic structure has to be engineered as well. Therefore, structure development usually has to deal with a higher number of design parameters, raising the need for simulation tools and optimization algorithms. In addition to more sophisticated design procedures, production planning for composite structures gets more challenging as well. For metallic structures, manufacturing usually starts with semi-finished parts having material properties mostly set as in the final product. The material properties of composites are mainly determined by the manufacturing processes. Properties such as fiber volume fraction or fiber orientation and imperfections like fiber undulations or inclusions are highly dependent on manufacturing. Therefore process stability has a large impact on structural characteristics. Design mostly accounts for the resulting uncertainties with high knock-down factors for assumed material properties, i.e. decreased lightweight potential.},

keywords = {Aerospace, Composite Structures, Fuselage, Preliminary design},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{Biel2013,

title = {Optimization of the Structure and the Infusion Process of a CFRP Fuselage Stiffener, according to the Fiber Reorientation by the Draping Process},

author = {Andreas Biel and Gerhard Ziegmann and Dieter Meiners and Onur Deniz and Peter Horst},

year  = {2013},

date = {2013-09-11},

booktitle = {SETEC},

abstract = {Design optimization plays a vital role in Aerospace Industry due to its challenging requirements that are not only based on mechanical aspects but also in manufacturing processes. Besides, manufacturing processes cause imperfections and variations on the structure which could be estimated by advanced simulations that result in expensive computation processes. On the other hand, it has been an issue to obtain global optima of the objective function of structures such as CFRP stiffened fuselage panels whose mechanical system responses are generally evaluated by Finite Element calculations.



This paper proposes a global optimization process on an innovative CFRP fuselage panel which simultaneously covers stability criterion and draping simulation of fiber textiles that is considered as a manufacturing effect. Genetic algorithms were chosen as an optimization technique to reach global optima. A parametric FEM model generator was developed under periodic boundary conditions in order to obtain buckling modes and corresponding failure criterions during the parameter variation. The shear angles of the fibers arising due to the draping process were considered as production constraint and represented with the surrogate model by RBF-ANN in the optimization loop. Different infusion strategies are simulated in a final step to find the optimal resin infusion process for the obtained fuselage stiffener.



This method presents an optimization frame that covers the production failures of draping process and its influence on structural design. Furthermore this optimization process can be modified with other undetermined production constraints that are predicted by simulation.},

keywords = {Composite Structures, Draping Simulation, Fuselage, Infusion Process},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{Deniz2013,

title = {Simulation Based Design Optimization of a Cfrp Fuselage Panel According to Draping Process of Carbon Fibre Textiles Using Evolutionary Algorithms and Response Surface Methods},

author = {Onur Deniz and Andreas Biel and Peter Horst and Gerhard Ziegmann and Carsten Schmidt},

year  = {2013},

date = {2013-05-03},

booktitle = {Sampe},

journal = {Sampe},

abstract = {Design optimization plays a vital role in Aerospace Industry due to its challenging requirements that are not only based on mechanical aspects but also in manufacturing processes. Besides, manufacturing processes cause imperfections and variations on the structure which could be estimated by advanced simulations that result in expensive computations. On the other hand, it has been an issue to obtain global optima of the objective function of structures such as CFRP stiffened fuselage panels whose mechanical system responses are generally evaluated by Finite Element calculations.

This paper proposes a global optimization process on an innovative CFRP fuselage panel which simultaneously covers stability criterion and draping simulation of fiber textiles that is considered as a manufacturing effect. Genetic algorithms were chosen as an optimization technique to reach global optima. During the optimization process, a modified Response Surface Method that is based on artificial neural networks (RBF-ANN) [1] is carried out in order to reduce the computational effort and to couple the simulation inputs and outputs in the optimization frame. 

A parametric FEM model generator was developed under periodic boundary conditions in order to obtain buckling modes and corresponding failure criterions during the parameter variation. The shear angles of the fibers arising due to draping process were considered as production constraint and represented with the surrogate model by RBF-ANN in the optimization loop.

This method presents an optimization frame that covers the production failures of draping process and its influence on structural design. Furthermore this optimization process can be modified with other undetermined production constraints that are predicted by simulation.

REFERENCES

[1]	K.Lindhorst, M. C. Haupt,  P. Horst,  “ Usage of time domain surrogate model approaches for transient, nonlinear aerodynamics within aero-structural coupling schemes”  presented in"30th AIAA Applied Aerodynamics Conference", 25-28th June 2012, New Orleans, USA 

},

keywords = {Composite Structures, Design Optimization, Draping Simulation, Fuselage},

pubstate = {published},

tppubtype = {inproceedings}

}