Date on Master's Thesis/Doctoral Dissertation

5-2020

Document Type

Doctoral Dissertation

Degree Name

Ph. D.

Department

Mechanical Engineering

Degree Program

Mechanical Engineering, PhD

Committee Chair

Berfield, Thomas

Committee Co-Chair (if applicable)

Bradshaw, Roger

Committee Member

Bradshaw, Roger

Committee Member

Hsu, Keng

Committee Member

Yang, Li

Author's Keywords

MEAM; polyvinylidene; fluoride; PVDF; material extrusion; additive manufacturing

Abstract

Beyond the beneficial characteristics of smart polymers associated with all polymers such as flexibility and cost fabrication, smart materials exhibit multifunctional behaviors. The prospect of integrating structural and sensing/actuation capabilities into a single structure gives design engineers an ability to innovate highly novel, multi-functional creations. Polyvinylidene Fluoride (PVDF) is one of the widely used multi-functional materials which offers a variety of desirable material properties. It possesses exceptional chemical and UV resistance, biocompatibility, low processing temperature and affordable price making it a competitive choice for many commercial applications. In addition, among polymers, PVDF is simply the most dominant piezoelectric polymer. On the other hand, material extrusion additive manufacturing technique helps to fabricate parts with different levels of complexity which can be joined with PVDF advantageous properties to be useful for different purposes. However, due to high thermal expansion and low surface energy of PVDF material, fabrication of this semi-crystalline thermoplastic polymer via material extrusion process is challenging and commonly results in substantial stress accumulation during filament extrusion and unwanted distortion in printed parts. In order to facilitate the printing challenges, advanced manufacturing techniques and optimal printing parameters were employed to create viable 3D printed PVDF structures with a balanced mix of mechanical and electromechanical characteristics. In addition, effect of deposition parameters on potential piezoelectric properties of PVDF 3D additively manufactured components were investigated. Moreover, in order to enhance net piezoelectric properties of fabricated parts, impact of post processing methods like annealing process and corona poling on piezoelectric behavior of printed samples were evaluated. Also, microscale zirconium tungstate particulates with a negative coefficient of thermal expansion were added to PVDF matrix in the attempt to decrease the total coefficient of thermal expansion of the composite and improve the printability of PVDF materials. Experimental and simulation methods were employed in order to control and minimize component warping and residual stress in the printed objects. Successful completion of this research will help enable products and prototypes that exhibit multi-functional behavior to be rapidly manufactured, a capability that will provide benefits in a variety of applications.

Download

Share

COinS