Northwestern University

Wed 11:00 AM

SPREE Seminar: Marco Salviato

When: Wednesday, May 29, 2019
11:00 AM - 12:00 PM  

Where: Technological Institute, A230, 2145 Sheridan Road, Evanston, IL 60208 map it

Audience: Faculty/Staff - Student - Public - Post Docs/Docs - Graduate Students

Contact: Tierney Acott   847.491.3257

Group: McCormick - Civil and Environmental Engineering

Category: Lectures & Meetings


Composites for the Next-Generation Aerospace Structures: Multiscale Design and Simulation

Emerging manufacturing technologies have provided engineers with an unprecedently broad design space. Laser lithography has enabled the development of lattice materials with sub-micron resolution. Multi-material additive manufacturing has allowed the design of multi-phase systems with novel physical and mechanical properties. Automated fiber deposition along curvilinear paths has introduced new ways to achieve damage tolerance of composite structures.

A common theme of the multi-phase systems resulting from the foregoing technologies is the absence of a clear boundary between the structure and the material. In fact, the size of the heterogeneous phases is often comparable to the length-scales characterizing the structural design variables. In this context, both the constituents and their arrangement substantiate the performance of the system.

This talk begins describing the ongoing projects at the laboratory for the Multiscale Analysis of Materials and Structures (MAMS) aimed at leveraging the state-of-the-art manufacturing technologies to develop the next generation of composite aerospace structures. The concept of “origami and aerogami composites” is introduced along with their applications to deployable structures and active aerodynamic control surfaces. The use of automated fiber placement to manufacture holomorphic fiber composites with unprecedented damage tolerance and multifunctional behavior is discussed as well. Then, the efforts of the MAMS lab on advancing the recyclability and manufacturability of composites via the use of Discontinues Fiber Composites (DFCs) are described.

The advancement of the foregoing designs depends on the formulation of proper multiscale simulation tools and experimental protocols. This is the subject of the second part of the talk which introduces a multiscale stochastic framework for the simulation of damage and fracture in fiber composites. From in-situ experiments and size effect tests, it is shown that the mechanical behavior of the matrix in polymer composites at the microscale is substantially different from the one exhibited at the macroscale. In fact, the microscale strength can be from six to ten times larger than the one measured in typical lab specimens, reaching values comparable to light alloys. At the same time, the microscale fracture energy is about forty to fifty times lower than the macroscale, making the matrix inherently more brittle. To capture this transition from pseudo-ductile to brittle behavior, a two-scale cohesive model is introduced along with a stochastic description of the size effect on the strength. Its capability of capturing the statistical-energetic size effect in polymer composites is discussed by a thorough analysis of in-situ tests and size effect tests on thermoset polymers and fiber composites. Finally, the importance of the proposed stochastic framework for the design of composite aerospace structures is discussed.

Dr. Salviato is assistant professor at the Departments of Aeronautics and Astronautics and Materials Science and Engineering at the University of Washington where he has served as the PI of the laboratory for the Multiscale Analysis of Materials and Structures (MAMS lab) since 2015. Dr. Salviato obtained a Ph.D. in Theoretical and Applied Mechanics from the University of Padova (Padova, Italy) in 2013 with a doctoral dissertation focusing on the experimental characterization and computational modeling of polymer nanocomposites. He later joined the Department of Civil and Environmental Engineering at Northwestern University as a postdoctoral scholar (2013-14) and research assistant professor (2014-15).

Dr. Salviato’s research and teaching interests lie in the area of Computational Mechanics and Fracture Mechanics of Quasibrittle Solids. He focuses on understanding the mechanical behavior of materials and structures at multiple length-scales through the formulation of advanced computational and analytical approaches and new experimental techniques. He believes that the next-generation, damage-tolerant infrastructure will be enabled by the elimination of the old dichotomy between the concepts of “structure” and “material”. In 2017, Dr. Salviato’s work on quasibrittle fracture mechanics and scaling was recognized by the prestigious ASME Haythornthwaite Young Investigator Award for “excellence in theoretical and applied mechanics”.

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