Session: 12-20-01: Composite Materials and Mechanics

Paper Number: 147263

147263 - Fabrication and Characterization of Nanophased Polyurethane Foam and 3d Printed Polylactic Acid Core Materials for Sandwich Composites 

Sandwich composite structures are extensively used in automotive, aircraft, rapid transport, and naval industries due to their reduced weight, high rigidity, and low maintenance costs. In such structures, fabrication includes two strong facesheets that are usually made of either glass or carbon fiber reinforced polymer matrix composites that are separately by a relatively thicker core material sandwiched between the facesheets. Traditional core materials are usually made of low-density materials such as aluminum or aramid in the form of a honeycomb or cellular foam. This type of sandwich construction provided very high bending stiffness/weight properties ideal for making advanced structural components in many industries.

In recent times, 3D printing or additive manufacturing has gained lot of attention in which many complex 3D structures are constructed at a rapid rate without wasting any material that is normally the case of traditional fabrication wherein a structure is made by subtractive process involving significant machining and finishing operations. Taking advantage of the progress in 3D printing, the current study is investigating the making of hollow and foam filled 3D printed polylactic acid core constructions for use in sandwich composites. In addition, polyurethane foam is modified with four different types of Nanoclay at 0.5 and 1 wt.% loading. For the 3D printed core, fused filament fabrication (FFF)/ fused deposition molding (FDM) method, which is an open source, is utilized. Nominal thickness of core used in sandwich construction is about 0.5 inches. Three different configurations of lattice structured core constructions are developed. Lattice cores were designed using Autodesk Inventor CAD software. With the help of this software, users can produce highly accurate 3D drawings with a variety of features. Three different lattice structures considered in the current study include: a) zero vertical strut lattice core, b) single vertical strut lattice core, and c) five vertical strut lattice core. A 2-part polyurethane foam was used to fill the open spaces in the lattice structure of 3D printed core material in a closed mold to keep the foam within the lattice.

Quasi-static compression and 3-point bend flexure test were conducted on these core materials. Results of the tests showed that all the foam core samples with nanoclay had higher flexural properties compared to the foam without nanoclay. All 3D printed core samples showed three folds increase in the flexural properties. For the compression tests, a 50% deformation limit was set on the tests. Only few of the nanophased samples had higher compressive properties compared to those without nanoclay. For the 3D printed lattice cores, zero vertical strut core samples failed around 4kN load with the struts buckling under the load. On the other had single and five vertical strut lattice core samples did not fail even after loading the samples till the load cell limit of the 5kN machine was reached due to the vertical struct bearing significant load. Currently foam filled lattice core struts samples are being prepared for both flexural and compressive tests. Details of the design, fabrication of 3D printed lattice structures, fabrication of composites and flexural characterization will be presented.

Presenting Author: Mahesh Hosur Texas A&M University-Kingsville

Presenting Author Biography: Mahesh Hosur received his education from India with a Bachelor of Engineering (B.E.) degree in Civil Engineering from Karnataka University (1985), Master of Technology (M. Tech.) degree in Aeronautical Engineering from Indian Institute of technology, Bombay (1990), and Doctor of Philosophy (Ph.D.) in Aerospace Engineering from Indian Institute of Science, Bangalore (1996). He worked as Scientist for one year in Aeronautical Development Agency before coming to the USA. After serving Tuskegee University for 21 years, he joined Texas A&M University-Kingsville (TAMUK) in his current position in August 2018. His teaching and research interests are in advanced composite materials, nondestructive evaluation, experimental and structural mechanics. Over last 25 years, He has led research efforts of nearly $36.5 M as Principal Investigator and over $40 M as Co-Principal Investigator. He has graduated 12 Ph.D. and 37 M.S. students and advised over 50 undergraduate students besides mentoring junior faculty members. He has authored or coauthored 4 books, 7 book chapters, 125 refereed articles in journals and over 220 refereed articles in conference proceedings besides numerous technical reports. He has received honors which include recognition as a Fellow of American Society for Mechanical engineers, Faculty Achievement Award at Tuskegee University and Russell Brown Award from Tuskegee University Sigma Xi Chapter.

Authors:

Durga Prasad Gorijala Texas A&M University-Kingsville
Mahesh Hosur Texas A&M University-Kingsville
Deepak Bommarapu Texas A&M University-Kingsville
Job Gonzales Texas A&M University-Kingsville
Rajashekar Mogiligidda Texas A&M University-Kingsville