HAO YIN

 

PhD Candidate of Civil Engineering

Northwestern University

Google Scholar                               ORCID: 0000-0003-4921-9786

Overview

I am a third-year Ph.D. candidate of Civil Engineering within the Mechanics, Materials, and Structures (MMS) Group at Northwestern University. I received a Bachelors of Engineering in Civil Engineering from China Agricultural University (CAU), China, and a Masters of Science in Civil Engineering from the University of Illinois at Urbana-Champaign (UIUC). Before joining Northwestern Univerisity, I worked on the mechanical analysis of rail infrastructure at the University of Illinois at Urbana-Champaign, Rail Transportation and Engineering Center (RailTEC). My current research interests include computational mechanics and computational geometry. Finite Element Method (FEM), Isogeometric Analysis (IGA), beam theories, and quasi-brittle material behaviors of wood, specifically. Also, I'm intensively using Abaqus and developing with Abaqus user subroutines for user-defined elements. 

Current Research

 

Computational modeling of wood, cross-laminated timber (CLT) and other quasi-brittle materials

A lattice model to simulate the microstructure of timber is currently under development, the main component of such lattice model is a 3D beam formulation characterized by (a) a general geometrical curvature and torsion of the axis as well as (b) an irregular cruciform cross-section. The various branches for the cross-section represent the walls of the wood cellular structure and the beam axis is the line at which various the cell walls meet. The beam formulation has been implemented in a finite element code by using the isogeometric analysis (IGA) technology. The verification of the implementation of 3D curved beam – the basic element of the lattice model has been finished, and verification results showed the proposed beam formulation has the adequate accuracy with beams with various geometric complexities. The implementation of connections between branches from different beams is undergoing, most of the fracture behaviors will be enforced at these connections, certain fracture constitutive laws used for quasi-brittle materials such as wood will be included.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Voronoi tessellation-based mesh generator for the mesoscale structure of wood

The lattice mesh generator for the microstructure of timber has been developed. The plane section mesh is featured by its Voronoi diagram based- plane partition algorithm, each polygon in the plane mesh can be seen as a cell and the boundaries can be seen as the cell walls of the wood. The radius of the timber section, the annual ring width, the earlywood and latewood distribution, and the representative cell size are taken into consideration in lattice mesh generation, while the longitudinal extrusion algorithm is characterized by the microfibril angle, the longitudinal fiber length, and the segment length distribution. The cutting box technique is also implemented to cut the 3D wood lattice mesh into any desired shape of the specimen.

Flow Lattice Model (FLM) for coupled diffusion-mechanical multiphysics problems

Previous implemented in LDPM Multiphysics (LDPM-M), the Flow Lattice Model (FLM) has been proved its capability of capturing the mass transport and heat transfer within the LDPM framework. Now coupled with LDPM, the multiphysics problems such as the thermal-hydro-mechanical problem can be investigated with the help of a two-way coupled FLM-LDPM analysis. As a dual system with the LDPM mesh system, the basic unit of FLM is called “edge element”, each edge element has two nodes and these nodes are the tetrahedron points in LDPM. The information for the mechanical analysis (LDPM) such as volumetric strain and crack opening and that for the diffusion analysis (FLM) such as temperature and water content can be exchanged on these nodes, and after information exchange, the two analyses can be solved concurrently until the convergence is reached.

Wood mesh generator
Wood mesh generator

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