No abstract

Additive manufacturing (AM), a substantial breakthrough over traditional manufacturing processes, has evolved significantly over the last few decades to meet industry demand. [1,2] It enables designers to utilize nature-inspired complex structures such as triply periodic minimal surface (TPMS) lattice structures. [3][4][5] The TPMS structures are desired and topologically ordered in many design applications due to their attractive properties, such as being lightweight and enhanced mechanical properties. [6,7] Another advantage of these structures is that their mechanical performance and functionality can be further improved by altering the thickness of given structures. [8][9][10] The quest for the ideal structure prompts new optimization proposals in the literature. Topology optimization (TO), which defines the best material distribution within the design domain, is one of the most extensively utilized optimization methods in the literature. [11][12][13] Among the various mathematical methods for TO, the solid isotropic material with penalization (SIMP), proposed by Rozvany et al., [14] gained significant attention due to its simplicity in implementation for the TO. The application of this approach to generate multiclass microstructures made of truss elements is available in the literature. For example, surrogate models for different truss-based structures are used in TO to minimize the compliance of the structure for a given volume ratio. The methodology was demonstrated on 2D and 3D case studies. [15] In another study, [16]

Due to their high specific strength, toughness, and corrosion and wear resistance characteristics, CoCrMo alloys are widely used in different industries and applications: wind turbines and jet-engine components, orthopedic implants, dental crowns, etc. The aim of this paper is to investigate the effect of lattice parameters on the compressive behavior of laser powder bed fusion (LPBF) parts from CoCrMo material. Build orientation, volume fraction, and lattice type are chosen as input parameters or control factors, and compressive yield strength (σy), elastic modulus (E), and specific energy absorption are chosen as the output or performance parameters for optimization. The Taguchi experimental design method is used in the arrangement of lattice parameters during experimental studies. The level of importance of the lattice parameters on σy, E, and specific energy absorption is determined by using analysis of variance (ANOVA). At the same material volume fractions, Diamond specimens showed higher σy and specific energy absorption than Gyroid and Primitive specimens, except σy at 0.4 volume fraction, where a Gyroid specimen showed the best result. The experimental and statistical results revealed that volume fraction and build orientation were found to be the major and minor effective factors, respectively, for all performance parameters (σy, E, and specific energy absorption). The effect of volume fraction on σy, E, and specific energy absorption was found to be 85.11%, 91.83%, and 57.71%, respectively. Lattice type was found to be the second-ranking factor, affecting σy, E, and specific energy absorption with contributions of 11.04%, 6.98%, and 39.40%, respectively. Multi objective optimization based on grey relation analysis showed that a Diamond specimen with 0.4 volume fraction and 45° build orientation was the best parameter set for the investigated performance outputs.

Yüksek ısı transfer kabiliyeti, enerji absorbe edebilme ve ses izolasyonu özelliklerinden dolayı kafes yapılar havacılık, otomotiv ve biyomedikal sanayii başta olmak üzere bir çok alanda kullanılmaktadır. Kafes yapıların bu kabiliyetleri üzerinde farklı proses ve geometrik parametreler etkili olmaktadır. Farklı endüstriyel uygulamalarda, ilgili kafes yapısının uygun proses ve geometrik parametreler ile birlikte kullanılmasının, uygulama sonucu elde edilen verimi arttıracağı bilinen bir gerçektir. Bu çalışma, Taguchi deney tasarımı kullanarak, kafes yapılarda, kafes yapı çeşidinin, inşa yönünün ve hacim oranının, üretimden sonra parçada meydana gelecek çarpılma, yüzey pürüzlülüğü ve duvar kalınlık değişimi üzerindeki etkisini deneysel olarak incelemeye odaklanmıştır. Üretim için lazer toz yatağı füzyon yöntemi ve CoCrMo malzeme kullanılmıştır. Her bir parametrenin çarpılma, yüzey pürüzlülüğü ve duvar kalınlık değişimi üzerindeki etkisi ve optimum parametre seti, değişkenlerin analizi (ANOVA) metodu ile bulunmuştur. Yüzey pürüzlülüğü için en optimum parametre seti elmas kafes yapısı, 0,2 hacim oranı ve 90o inşa yönü olarak belirlenmiştir. Duvar kalınlığındaki değişim için ise en optimum parametre seti gyroid kafes yapısı, 0,4 hacim oranı ve 45o inşa yönü olarak belirlenmiştir.

Graded TPMS topologies display excellent mechanical and thermal properties. Design schemes targeting optimal performance exist, but final reconstructed designs still suffer from performance degradation. To overcome this challenge, we propose an automated design framework based on the integration of a homogenization-based topology optimization scheme and a new mapping strategy. Optimized designs obtained using a modified SIMP technique are reconstructed as graded gyroid structures. Unlike mapping strategies using relative density values prior to TPMS infill, for the first time we make use of readily available adjoint sensitivities for mapping optimal densities to graded gyroid structures. Results show that the proposed framework delivers performance preserving graded designs when compared to original optimized designs obtained using OPTISTRUCT and superior performance in comparison to standard density-based mapping methods. The resulting graded design is manufactured using additive manufacturing and three-point bending tests are performed confirming simulation results and demonstrating the applicability of presented design scheme.