Skip to Main Navigation. Each navigation link will open a list of sub navigation links.

Skip to Main Content

Apply Now to the University of Wyoming apply now
Visit Campus
Download UW Viewbook
Give to UW
view of engineering building on University of Wyoming Campus

News

2019

December 11, our paper entitled "Dislocation density informed eigenstrain based reduced order homogenization modeling: verification and application on a titanium alloy structure subjected to cyclic loading" is accepted by Modelling and Simulation in Materials Science and Engineering! Congradulations!


November 11, Xiang Zhang presented at ASME IMECE 2019 in Salt Lake City, UT. The title of Xiang’s presentation was: “Modeling of Process-Induced Residual Deformations in Frontal Polymerization based Manufacturing of Thermosetting Polymer Components”.

Abstract

Fontal polymerization (FP) is a rapid and energy-efficient manufacturing process for polymer and polymer composites. In FP-based manufacturing, a polymerization front is firstly initiated by a local heat stimulus to activate the catalyst present in the monomer solution, upon which the heat from the exothermic polymerization of the monomer maintains and self-propagates the reaction front, rapidly transforming the monomer into fully cured polymer. To further increase the manufacturing efficiency, a multi-point initiation approach is adopted to initiate multiple fronts and cure different regions of the manufactured part simultaneously. However, localized residual deformations is experimentally observed where fronts merge, leading to deteriorated properties at these locations. To capture the formation of residual deformations in the FP-based manufacturing process, a coupled thermo-chemo-mechanical model is developed. In this model, a fully coupled thermo-chemical model is first used to replicate the thermal and degree of cure history associated with the FP process. Key characteristics of the front, including front velocity and temperature are compared with experimental measurements. The obtained temperature and degree of cure are then fed into a static structural finite element solver that utilizes temperature- and degree-of-cure-dependent properties to solve for the displacement field. The predicted process-induced strain field is compared with Digital Image Correlation (DIC) measurements. We also explore the possibility of regulating the temperature and cure history at the front merging location to alleviate the residual deformations. 

September 19, our paper entitled "Manufacturing of unidirectional glass-fiber-reinforced composites via frontal polymerization: A numerical study" is accepted by Composite Science and Technology! Congradulations!


August 27,  Xiang Zhang officially started as a an assistant professor in the Mechanical Engineering Department at the University of Wyoming! Welcome!


July 29, Xiang Zhang presented at USNCCM 2019 in Austin, TX. The title of Xiang’s presentation was: “Modeling and Design of a New Printing Process for 3D Freeform Polymer Components based on Frontal Polymerization”.

Abstract

A rapid and energy-efficient manufacturing process for polymer and polymer composites called frontal polymerization (FP) was recently developed. In FP-based manufacturing, only an initial local heat stimulus is required to activate the polymerization, upon which the heat from the exothermic polymerization of the monomer creates a self-propagating polymerization front that transforms the monomers into fully cured polymers. A 3D printing technique that uses FP to simultaneously cure the printed material as it is deposited has also been recently introduced for free-standing polymer components. During this printing process, the polymerizing front follows the printing nozzle and rapidly transforms the viscoelastic filament into a stiff thermoset, thereby eliminating the need for support structures and post curing process and providing high printing accuracy compared to traditional direct ink writing. In this presentation, we start by introducing a coupled thermo-chemo-mechanical model specially developed to model the evolution of temperature, degree of cure, and strain fields during the FP process. The model is first validated against experimental measurements and then used to probe the front characteristics under different experimental settings. We then focus on the development of a design diagram for FP-based 3D printing to maximize the printing efficiency (i.e., maximum printing velocity) while maintaining the desired printing accuracy (i.e., limited deformation of the printed filament). The design space contains parameters that characterize the settings of the printer (e.g., ink temperature, extruding pressure, length and diameter of the nozzle), the nature of the ink (e.g., initial degree of cure and cure kinetics associated with the chosen ink composition), and the printing environment (e.g., ambient temperature and air flow rate).The constraints are associated with equilibrated printing for which the front velocity equals the printing speed, the printing accuracy achieved by limiting the deflection of the deposited filament, the capability of the printer, and non-blocking of the nozzle by a threshold depositing temperature.

July 24, our paper entitled "Experimental and numerical study of mechanical properties of multi-phase medium-Mn TWIP-TRIP steel: Influences of strain rate and phase constituents" is accepted by Acta Materialia! Congradulations!


May 15, our paper entitled "IGFEM-based shape sensitivity analysis of the transverse failure of a composite laminate" is accepted by Computationsl Mechanics. Congradulations!


April 29, Xiang Zhang accepted the offer as an assistant professor in the Mechanical Engineering Department at the University of Wyoming! Congradulations!

 

 


Contact

Xiang Zhang, Ph.D.,

Assistant Professor of Mechanical Engineering Department

Room 335B, EERB
1000 E. University
Dept. 3295
Laramie, WY 82071
EmaiL: xiang.zhang@uwyo.edu
Phone: 307-766-42381000
Fax: 307.766.2695

1000 E. University Ave. Laramie, WY 82071
UW Operators (307) 766-1121 | Contact Us | Download Adobe Reader

Accreditation | Virtual Tour | Emergency Preparedness | Employment at UW | Privacy Policy | Harassment & Discrimination | Accessibility Accessibility information icon