Additive manufacturing and topology optimization: A design strategy for a steering column mounting bracket considering overhang constraints

Abstract

In the present paper, the use of the topology optimization in a metal Additive Manufacturing application is discussed and applied to an automotive Body-in-White component called dash. The dash is in the front area of the Body-in-White, between the left-hand-side shock-tower and the Cross Car Beam, and its task is to support the steering column. The dash under investigation is an asymmetric rib-web aluminium casting part. The influence of Additive Manufacturing constraints together with modal and stiffness targets is investigated in view of mass reduction. The constraints drive the topology result towards a feasible and fully self-supporting Additive Manufacturing solution. A simplified finite element model of the steering column and of the Body-in-White front area is presented, and the limiting assumption of isotropic material for Additive Manufacturing is discussed. The optimization problem is solved with a gradient-based method relying on the Solid Isotropic Material with Penalization and on the RAtional Material with Penalization algorithms, considering the overhang angle constraint with given build directions. Three metals are tested: steel, aluminium and magnesium alloys. Topology optimization results with and without overhang angle constraints are discussed and compared. The aluminium solution, preferred for its lesser weight, has been preliminarily redesigned following the optimization results. The new dash concept has been validated by finite element considering stiffness, modal responses, and buckling resistance targets. The proposed dash design weighs 721 g compared to the 1537 g of the reference dash, with a weight reduction of 53%, for the same structural targets.

Steering column support topology optimization including lattice structure for metal additive manufacturing

“…The assembly includes: a Cross-Car beam (CCB), two lower extrusions, the vertical pillar connecting the CCB to the tunnel, two lateral castings connecting the CCB to the front hinge pillars, the Steering Column Support (SCS), and the steering column sub-assembly, see Figure 4(a) and Figures 1 to 3 in Mantovani et al 26 All the extruded parts are shown in green, the castings are in red, while the sheets are shown in blue. The extruded and the sheets parts are modelled with four-noded isoparametric shell elements with an average size of 4 mm.…”

“…18,19 Several algorithms have been introduced to overcome AM production constraints in TO, using Solid, Isotropic Material with Penalization (SIMP) or level-set method. [20][21][22][23][24][25] Mantovani et al 26 adopted an AM-oriented TO in the design of an automotive steering column bracket to reduce the amount of support structures that are discarded at the end of the process.…”

Proposal of a standard for 2D representation of bio-inspired lightweight lattice structures in drawings

“…On the other hand, some limitations of the Standard suggests the need for further developments. The proposed Standard can handle only voxel-based lattice structures 20 of the strut-and-node arrangement type, while it is still not able to model other kinds of periodic shapes, such as Triply Periodic Minimal Surface (TPMS) structures. A reduced portfolio of unit cell types (Figure 3) and cross-section topologies is noticed in this first embodiment of the Standard and add-on developed for its testing.…”

“…For further details about this kind of structures, the reader is addressed to the source. 20 Conformal lattice structures. The last type of lattice considered in this project is the conformal one.…”

Synergy between topology optimization and additive manufacturing in the automotive field

“…In this contribution, a methodology similar to the one presented by Barbieri et al 27,28 and Mantovani et al 29 was applied to determine the optimal material distribution for an upright to be produced in aluminum alloy by laser-powder bed fusion (L-PBF). 30 L-PBF discloses extreme freedom in geometry, which also enables the production of the complicated shapes resulting from TO.…”