Dynamic behavior of concurrently printed functionally graded closed cell foams. (1st November 2021)

• Record Type: Journal Article
• Authors: Dileep, Bonthu; Prakash, Rohith; Bharath, H.S.; Jeyaraj, P.; Doddamani, Mrityunjay
• Is Part Of: Composite structures. Volume 275(2021)
• Publication Date: 2021-11-01
• Subjects: HDPE -- GMB -- FGFs -- Damping -- Buckling; Composite construction -- Periodicals; Composites -- Périodiques; 624.18
• DOI: 10.1016/j.compstruct.2021.114449
• Languages: English
• ISSNs: 0263-8223

Abstract

Highlights: Functionally graded syntactic foams (FGFs) are 3D printed for the first time. Weight-saving potential of 3D printed graded foams of glass micro balloons in HDPE matrix is between 9.27 and 14.56%. Foams exhibited better specific compressive properties compared to neat HDPE. FGF exhibited better specific compressive strength than all 3D printed samples and is 1.2 times of pure HDPE. FGFs exhibited better energy absorption than other plain foams and is 35 to 50 % more than pure HDPE. Abstract: In this work, functionally graded foams (FGFs) of closed cell types are three-dimensionally printed (3DP) concurrently. These closed cell syntactic foams are manufactured by reinforcing 20, 40, and 60 vol% hollow glass microballoons (GMBs) in the high density polyethylene (HDPE) matrix and are investigated for their mechanical buckling and free vibration response. The critical buckling load ( P cr ) of the FGFs are evaluated using the Double Tangent Method (DTM), Modified Budiansky Criteria (MBC), and Vibration Correlation Technique (VCT). It is observed that P cr evaluated by all three methods are in good agreement. Among all FGFs, FGF-2 exhibited higher buckling strength with 22–26% higher than FGF-1 and FGF-3. Under no-load and uniaxial compressive loads, the first three natural frequency of FGFs and their corresponding damping factors are evaluated. At first mode, the natural frequency of FGFs decreases in the pre-buckling zone and started increasing in the post-buckling zone. Damping factor exhibited reverse trend compared to the trend shown by the natural frequencies. Among all FGFs, FGF-2 (20-40-60 GMB gradation) exhibited better natural frequency. Experimental results are compared with a finite element based simulation results.