On optimal structural remodeling

We present the problem of remodeling a given structure such as to improve structural performance optimally within a specified available resource. The development pertains to all types of problems where the mode of structural response is governed by an extremum principle. A variational formulation is used, and the idea is illustrated for maximum-stiffness remodeling of single-purpose structures.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/45213/1/10957_2004_Article_BF00933441.pd

Structural topology and shape optimization for a frequency response problem

A topology and shape optimization technique using the homogenization method was developed for stiffness of a linearly elastic structure by Bendsøe and Kikuchi (1988), Suzuki and Kikuchi (1990, 1991), and others. This method has also been extended to deal with an optimal reinforcement problem for a free vibration structure by Diaz and Kikuchi (1992). In this paper, we consider a frequency response optimization problem for both the optimal layout and the reinforcement of an elastic structure. First, the structural optimization problem is transformed to an Optimal Material Distribution problem (OMD) introducing microscale voids, and then the homogenization method is employed to determine and equivalent “averaged” structural analysis model. A new optimization algorithm, which is derived from a Sequential Approximate Optimization approach (SAO) with the dual method, is presented to solve the present optimization problem. This optimization algorithm is different from the CONLIN (Fleury 1986) and MMA (Svanderg 1987), and it is based on a simpler idea that employs a shifted Lagrangian function to make a convex approximation. The new algorithm is called “Modified Optimality Criteria method (MOC)” because it can be reduced to the traditional OC method by using a zero value for the shift parameter. Two sensitivity analysis methods, the Direct Frequency Response method (DFR) and the Modal Frequency Response method (MFR), are employed to calculate the sensitivities of the object functions. Finally, three examples are given to show the feasibility of the present approach.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47814/1/466_2004_Article_BF00370133.pd

Emissions: world has four times the work or one-third of the time

The past decade of political failure on climate change has cost us all dear. It has shrunk the time left for action by two-thirds. In 2010, the world thought it had 30 years to halve global emissions of greenhouse gases. Today, we know that this must happen in ten years to minimize the effects of climate change. Incremental shifts that might once have been sufficient are no longer enough

A Regularized Discrete Laminate Parametrization Technique with Applications to Wing-Box Design Optimization

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/97055/1/AIAA2012-1519.pd