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See detailFatigue resistant designs using stress-based topology optimization
Collet, Maxime ULiege; Bauduin, Simon ULiege; Fernandez Sanchez, Eduardo Felipe ULiege et al

Conference (2017, September 15)

Fatigue is an important mode of failure in mechanical engineering and accounting for it as soon as the early stage of design using topology optimization sounds primordial. Structures undergoing high-cycle ... [more ▼]

Fatigue is an important mode of failure in mechanical engineering and accounting for it as soon as the early stage of design using topology optimization sounds primordial. Structures undergoing high-cycle fatigue can be described by the stress-based approach and then a stress-based topology optimization framework, which has received great interest since almost 20 years because of the innovative designs that can be achieved to answer strength requirements, can be used. Literature reports many good results for shape optimization [Mrzyglod & Zielinsky(2006)] whereas in the eld of topology optimization several authors have shown that considering fatigue in an optimization framework leads to more relevant solutions where fluctuating loads are involved [Holmberg E.(2015), Collet et al(2016), Sv ard(2015)]. The good behaviour of the implementation of an advanced fatigue criterion, i.e. the multiaxial Dang Van criterion [Dang Van et al(1989)] is first investigated in the framework of a density-based topology optimization problem. The choice of this fatigue criterion is justifed by its good applicability in automotive or aeronautic industry as well as its relevancy with respect to experimental results. We present the sensitivity analysis with stress constraints and present some classical benchmarks to illustrate the behaviour of the optimized solution. In a second time, the fatigue resistance is introduced in the well-known microstructural design [Sigmund (2000)] also know as architectured material design which are now considered in mechanical engineering because of their manufacturability thanks to additive manufacturing processes. Ensuring the fatigue resistance of the cellular material will by extension ensure the structural integrity of the overall structure itself. The optimization is performed by using the MMA optimizer [Svanberg(1987)] whereas the singularity phenomenon of the stress constraints is circumvented by using the qp-relaxation [Bruggi(2008)]. Both types of optimization framework are evaluated in term of their numerical performances and are compared to classical results generated by a regular stress-based topology optimization. Finally, the results are 3D-printed to assess for their manufacturability. [less ▲]

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See detailFatigue resistant designs using stress-based topology optimization
Collet, Maxime ULiege; Bauduin, Simon ULiege; Fernandez Sanchez, Eduardo Felipe ULiege et al

Conference (2017, June 08)

Stress based topology optimization has received great interest since almost 20 years because of the innovative designs that can be achieved to answer strength requirements. Fatigue is an important mode of ... [more ▼]

Stress based topology optimization has received great interest since almost 20 years because of the innovative designs that can be achieved to answer strength requirements. Fatigue is an important mode of failure in mechanical engineering and accounting for it as soon as the early stage of design using topology optimization sounds primordial. Literature reports many good results for shape optimization [Mrzyglod & Zielinsky(2006)] whereas in the field of topology optimization several authors have shown that considering fatigue in an optimization framework leads to more relevant solutions where fluctuating loads are involved [Holmberg E.(2015), Collet et al(2016), Svärd(2015)]. In order to check the good behavior of the implementation, we first investigate the implementation of an advanced fatigue criterion, i.e. the multiaxial Dang Van criterion [Dang Van et al(1989)], in the framework of a density-based topology optimization problem. The choice of this fatigue criterion is justifed by its good applicability in automotive or aeronautic industry as well as its relevancy with respect to experimental results. We present the sensitivity analysis with stress constraints and present some classical benchmarks to illustrate the behavior of the optimized solution. In a second time, we introduce the fatigue resistance in the well-known microstructural design [Sigmund (1999)]. The new additive manufacturing techniques allow to fabricate components exhibiting architectured materials. In this perspective, ensuring the fatigue resistance of the cellular material will by extension ensure the structural integrity of the overall structure itself. Both types of optimization framework are evaluated in term of their numerical performances and are compared to classical results generated by a regular stress-based topology optimization. Finally, the results are 3D-printed to assess for their manufacturability. [less ▲]

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See detailTopology optimization of mechanical components fabricated by additive manufacturing for a Shell Eco Marathon vehicle
Alarcon Soto, Pablo ULiege; Collet, Maxime ULiege; Bauduin, Simon ULiege et al

Conference (2017, June 07)

Since 2004, a team of students and researchers of University of Liege takes part to the Shell Eco Marathon race with a lightweight electric vehicle. The goal of this pedagogical project is to design ... [more ▼]

Since 2004, a team of students and researchers of University of Liege takes part to the Shell Eco Marathon race with a lightweight electric vehicle. The goal of this pedagogical project is to design, fabricate and operate a vehicle exhibiting the least energy consumption. A key factor to reduce the energy consumption is to minimize the vehicle mass. Besides the body structure made of CRFP, engineers have also to focus on the weight reduction of any mechanical parts of the powertrain, transmission and of rolling gear. The combination of topology optimization with additive manufacturing techniques allows to propose innovative designs exhibiting a high performance to weight ratio. Topology optimized designs are often characterized by a high geometrical complexity that is not possible to manufacture without 3D printing. This work presents the CAE design methodology that was developed to combine topology and shape optimization with 3d printing manufacturing. Novel developments both in shape and topology optimization have also been realized for the specific character of these components. The design methodology is illustrated with several applications of components of our new Eco Marathon prototype. They include a support for electric traction motors and different torque arms of the steering mechanism to be implemented in the new 2017 vehicle. The presentation is going to show the different design steps from the specifications and the formulation of the design problem to the 3D-printing of the parts: the topology optimization, interpretation and CAD reconstruction, shape optimization and detailed finite element verification of the solution. The optimization is performed thanks to the commercial software NX-TOPOL and the final CAD design is reconstructed in the CATIA environment software after a smoothing procedure in the NX-CAD environment. We show that the final design can be 3D-printed and a comparison with a design produced using traditional design approach is provided. [less ▲]

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See detailContributions to handle maximum size constraints in density-based topology optimization
Fernandez Sanchez, Eduardo Felipe ULiege; Collet, Maxime ULiege; Bauduin, Simon ULiege et al

in Fiebig, Sierk; Bletzinger, Kai-Uwe; Maute, Kurt (Eds.) et al Advances in Structural and Multidisciplinary Optimization (2017, June 05)

The maximum size formulation in topology optimization restricts the amount of material within a test region in each point in the design domain, leading to a highly constrained problem. In this work the ... [more ▼]

The maximum size formulation in topology optimization restricts the amount of material within a test region in each point in the design domain, leading to a highly constrained problem. In this work the local constraints are aggregated into a single one by p-mean and p-norm functions, classically used for stress constraints. Moreover, a new test region is investigated which is a ring instead of the classical circle around the element. These developments were implemented for compliance minimization with the MBB beam test case. Results indicate that p-mean performs better in the maximum size field than p-norm, because it underestimates the most violated constraint. This gives some relaxation to the problem that allows stiffer connections. Similar effect has been observed for the ring-shaped region which reduces the amount of holes that are introduced in the structure, specially in the connection of solid members. In addition, it is shown that the maximum size formulation allows the definition of the minimum gap between solid members which gives designers more control over the geometry. The developments have been illustrated and validated with compliance minimization tests of 2D-domains. [less ▲]

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See detailMicrostructural design using stress–based topology optimization
Collet, Maxime ULiege; Bruggi, Matteo; Noël, Lise ULiege et al

Conference (2016, September 12)

New additive manufacturing techniques break the limitations encountered for years when producing components descending from topology optimization. Classical design procedures focus on macro-structural ... [more ▼]

New additive manufacturing techniques break the limitations encountered for years when producing components descending from topology optimization. Classical design procedures focus on macro-structural optimization to sustain given loads but today innovative manufacturing processes allow considering structures exhibiting tailored microstructures, i.e. the well known microstructural design. The practical applications of structures including material design is mainly motivated by the greater performances that can be achieved compared to classical solutions. Microstructural design has been shown a great interest as attested by recent works. However, stress–based topology optimization has not yet been extensively exploited when addressing microstructural design using numerical homogenization though stress constraints is an important feature and have gained in interest in the field of topology optimization. This contribution investigates the problem of material design enforcing stress constraints within periodic microstructures by considering a representative volume element (RVE) subject to prescribed strain fields. The SIMP approach is adopted as material interpolation law while the optimization problems are solved using a sequential convex programming approach. In particular the well known method of moving asymptotes (MMA) is considered. Numerical homogenization is used to assess the effective elastic properties of the microstructures. The Von Mises stress criterion is used to impose the constraints on the stress level. This work discusses the formulation of a well-posed design problem as well as some numerical issues encountered. The developed solution procedure is first validated by comparison against analytical results, e.g. the single inclusion of Vigdergauz microstructure. [less ▲]

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See detailOverhanging Constraints in Addivitive Manufacturing Using Two Different Tools
Bauduin, Simon ULiege; Collet, Maxime ULiege; Duysinx, Pierre ULiege

Conference (2016, September 12)

Topology optimization is widely used as a design tool for advanced application in mechanical, aerospace and automotive industries. This technique offers an optimal distribution of a predetermined amount ... [more ▼]

Topology optimization is widely used as a design tool for advanced application in mechanical, aerospace and automotive industries. This technique offers an optimal distribution of a predetermined amount of material in a given design space. In the last years, a lot of efforts has been invested into the development of high performance methods such as homogenization, SIMP or BESO. However as the state of the art in manufacturing experiences evolution, a coupling between topology optimization and additive manufacturing is needed. Additive manufacturing has numerous advantages that fits the characteristics of topology optimized designs. It can manufacture highly complex design without high cost increase and furthermore continuous density material of the SIMP method could be manufactured by lattice structures. With all the opportunities given by the additive manufacturing the urge to bind the last one to topology optimization is heavily required. Specific constraints related to manufacturing issues have to be taken into account such as the need of supports structures to ensure a good heat evacuation during the manufacturing process, as well as to hold up overhanging section. Some researches have been done to try to include this constraint in the optimization problem such as Leary and al or Andrew T. Gaynor. However this work focuses on 2 different methods (projection scheme and mechanical approach) to tackle the overhanging problem and compare them . [less ▲]

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See detailOverhanging Constraints in Addivitive Manufacturing Using Two Different Tools
Bauduin, Simon ULiege; Collet, Maxime ULiege; Duysinx, Pierre ULiege

Poster (2016, August 23)

Topology optimization is widely used as a design tool for advanced application in mechanical, aerospace and automotive industries. This technique offers an optimal distribution of a predetermined amount ... [more ▼]

Topology optimization is widely used as a design tool for advanced application in mechanical, aerospace and automotive industries. This technique offers an optimal distribution of a predetermined amount of material in a given design space. In the last years, a lot of efforts has been invested into the development of high performance methods such as homogenization, SIMP or BESO. However as the state of the art in manufacturing experiences evolution, a coupling between topology optimization and additive manufacturing is needed. Additive manufacturing has numerous advantages that fits the characteristics of topology optimized designs. It can manufacture highly complex design without high cost increase and furthermore continuous density material of the SIMP method could be manufactured by lattice structures. With all the opportunities given by the additive manufacturing the urge to bind the last one to topology optimization is heavily required. Specific constraints related to manufacturing issues have to be taken into account such as the need of supports structures to ensure a good heat evacuation during the manufacturing process, as well as to hold up overhanging section. Some researches have been done to try to include this constraint in the optimization problem such as Leary and al or Andrew T. Gaynor. However this work focuses on 2 different methods (projection scheme and mechanical approach) to tackle the overhanging problem and compare them . [less ▲]

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See detailDesign of microstructures using stress-based topology optimization
Collet, Maxime ULiege; Bruggi, Matteo; Noël, Lise ULiege et al

Conference (2016, August 22)

This paper aims at designing microstructures using stress-based topology optimization. Most of the developments so far have been made for compliance design in various field of applications as reflected in ... [more ▼]

This paper aims at designing microstructures using stress-based topology optimization. Most of the developments so far have been made for compliance design in various field of applications as reflected in the literature. The emergence of the new additive manufacturing techniques allows to consider porous material, such as lattice structures for instance, which ca be used for the design of structural components subject to various solicitations. Those components must account for the stress level to prevent failure everywhere in the microstructures and by extension the whole structure itself. This work proposes to design such microstructures using topology optimization with limitation on the stress level within the microstructures before printing the result. The homogenization technique is used to determine the equivalent material properties. The issues and perspectives are also discussed. [less ▲]

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See detailTopology optimization for minimum weight with compliance and simpli ed nominal stress constraints for fatigue resistance
Collet, Maxime ULiege; Bruggi, Matteo; Duysinx, Pierre ULiege

in Structural and Multidisciplinary Optimization (2016)

This work investigates a simpli ed approach to cope with the optimization of preliminary design of structures under local fatigue constraints along with a global enforcement on the overall compliance. The ... [more ▼]

This work investigates a simpli ed approach to cope with the optimization of preliminary design of structures under local fatigue constraints along with a global enforcement on the overall compliance. The problem aims at the minimization of the weight of linear elastic structures under given loads and boundary conditions. The expected sti ness of the optimal structure is provided by the global constraint, whereas a set of local stress-based constraints ask for a structure to be fatigue resistant. A modi ed Goodman fatigue strength comparison is implemented through the same formalism to address pressure-dépendent failure in materials as in Drucker-Prager strength criterion. As a simplification, the Sines approach is used to de ne the equivalent mean and alternating stresses to address the fatigue resistance for an infinite life time. Sines computation is based on the equivalent mean and alternate stress depending on the invariants of the stress tensor and itsdeviatoric part, respectively. The so-called singularity phenomenon is overcome by the implementation of a suitable qp-relaxation of the equivalent stress measures. Numerical examples are presented to illustrate the features of the achieved optimal layouts and of the proposed algorithm. [less ▲]

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See detailSimplified fatigue resistance in mechanical engineering using topology optimization
Collet, Maxime ULiege; Bruggi, Matteo; Bauduin, Simon ULiege et al

Conference (2015, July 09)

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See detailDeterministic Manufacturing constraints for Optimal Distribution in the Case of Additive Manufacturing
Bauduin, Simon ULiege; Collet, Maxime ULiege; Duysinx, Pierre ULiege et al

Conference (2015, July 09)

An overview of the difficulties of coupling additive manufacturing to topology optimization with various solution founded and implemented.

Detailed reference viewed: 136 (23 ULiège)
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See detailTopology optimization of mechanical and aerospace components subject to fatigue stress constraints
Duysinx, Pierre ULiege; Collet, Maxime ULiege; Bauduin, Simon ULiege et al

Conference (2015, June 08)

While topology optimization has been based mostly on compliance type formulations, industrial applications call for more elaborated formulations including several restrictions on the local displacements ... [more ▼]

While topology optimization has been based mostly on compliance type formulations, industrial applications call for more elaborated formulations including several restrictions on the local displacements and the stress constraints in some critical zones. Topology optimization with stress constraints was initially considered in Duysinx & Bendsoe (1998). Later the stress constraint formulation was further extended to consider non equal stress constraints limits Bruggi & Duysinx (2012) and to improve the solution efficiency using different strategies such as global stress constraint formulations (Duysinx & Sigmund, 1998, Le et al. 2010). In the present work, the authors are investigating the formulations of stress constraint topology optimization to support the redesign of structural components that have to be fabricated using additive manufacturing. In this perspective, design problem requirements include tackling fatigue constraints during stress constrained topology optimization. The work investigates different formulations of fatigue resistance which could be appropriate in a topology approach. At first the classical approach of mechanical engineering based on SN curves and Goodman or Soderberg lines. The treatment of these fatigue restrictions can take advantage of former work developed for unequal stress constraints by considering mean and alternating components of the stress state. In a second step our research is now focussing on more complex situations (3D stress states) which require resorting to more advanced criteria. Dang Van fatigue theory (Dang Van, Griveau, Message, 1989) has been selected but calls for a more elaborated procedure that is currently validated. Topology optimized structural layouts predicted using classical stress criteria, Goodman and Dang Van theories are compared. [less ▲]

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See detailStress-based topology optimization with fatigue failure constraints
Collet, Maxime ULiege; Bruggi, Matteo; Bauduin, Simon ULiege et al

in Proceedings of the Fifteenth International Conference on Civil, Structural and Environmental Engineering Computing (2015)

This paper shows how the design of a structure can evolve when considering a stressbased topology optimization along with fatigue failure constraints. More precisely, fatigue failure is added in a stress ... [more ▼]

This paper shows how the design of a structure can evolve when considering a stressbased topology optimization along with fatigue failure constraints. More precisely, fatigue failure is added in a stress-based topology optimization Matlab code by following the approach of the design of machine elements, i.e. based on S-N curves or fatigue criteria. The fatigue is introduced through weel-known criteria for high-cycle fatigue such as the Sines and Crossland criteria. The paper presents how these criteria can be formulated for a topology optimization problem. Numerical results for both criteria are successively compared and discussed. The character of fatigue failure in the optimization procedure is illustrated as well as some issues that have to be improved in future work. [less ▲]

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See detailPoster: CONTRIBUTIONS TO TOPOLOGY OPTIMIZATION OF STRUCTURAL COMPONENTSMADE BY ADDITIVEMANUFACTURING
Collet, Maxime ULiege

Diverse speeche and writing (2015)

Detailed reference viewed: 50 (9 ULiège)