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For the stress-constrained topology optimization of a turbine disk under centrifugal loads, the jagged boundaries of the mesh and the gray densities on the solid/void interfaces could make the calculated stress field inconsistent with the actual value. It may result in overestimating the maximum stress and thus affect the effectiveness of stress constraints. This paper proposes a new method for predicting the maximum stress to overcome the difficulty. In the process, a predicted density is newly defined to obtain stable boundaries with thin layers of gray elements, a transition factor is innovatively proposed to evaluate the effects of intermediate-density elements, two different stiffness penalty schemes are flexibly used to calculate the elastic modulus of elements, and a linear stress penalty is further adopted to relax the stress field of the structure. The proposed approach for predicting the maximum stress value is verified by the analysis of a structure with smooth boundaries and the topology optimization of a turbine disk. An updating scheme of the stress constraint in the topology optimization is also developed using the predicted maximum stress. Some key ingredients affecting the optimization results are discussed in detail. The results prove the effectiveness and efficacy of the proposed maximum stress prediction and developed stress constraint methods.

Objective This study evaluated the clinical and pathological effects of the immunosuppressive agent mycophenolate mofetil (MMF) in rats with experimental autoimmune encephalomyelitis (EAE; a model of multiple sclerosis [MS]).Methods EAE rats were randomly divided into 4 groups: model alone (n= 7); low- or high-dose MMF (20 and 30 mg/kg per day, respectively, n= 6 each) orally for 14 days; methylprednisolone (20 mg/kg per day, n= 6) injected once daily for 3 days. Six normal Wistar rats served as controls. Clinical signs and histopathological findings were evaluated 14 days after treatment started.Results Oral administration of high-dose MMF significantly ameliorated the course of EAE in rats: cumulative clinical scores were lower and weight loss was less than in rats receiving methylprednisolone. The ameliorated disease course was associated with alleviation of histopathological signs of EAE. Treatment increased the blood proportion of CD8+, CD4+CD25+and CD4+CD45RA+T cells, with a concomitant reduced proportion of CD4+T cells and ratio of CD4+to CD8+T cells, compared with EAE model alone rats.Conclusions MMF may have pharmacological potential in MS treatment and these findings may help in understanding the pathophysiological mechanism of MS.

The paper presents a method to optimize build orientation and topological layout simultaneously in density-based topology optimization for additive manufacturing. Support structures are required in additive manufacturing of parts of complex shape. To eliminate or reduce support structures during the additive processes, we constrain the lower bound of the overhang angle of the optimized design. In this method, the build orientation and the density field used to represent the part are simultaneously optimized to satisfy the overhang angle constraints for part self-support. While these angle constraints are locally defined on every material point over the design domain, they are transformed into two global constraints through the Heaviside projection-based aggregations. The first directional gradient based global constraint controls the overhang angle of the solid/void interface inside the design domain to eliminate the internal supports. The second density-based global constraint controls the angle of the design domain boundary to reduce the external supports. Numerical examples on both 2D and 3D linear elastic problems are presented to demonstrate the validity and efficiency of the proposed formulations in the build orientation optimization and in the overhang angle control.