STRESS MECHANICS OF REINFORCED POLYESTER COMPOSITES

Yıl 2021, Cilt: 3 Sayı: 1, 39 - 54, 31.01.2021

Osaretın Meshach Dıckson Davıd Olodu

https://doi.org/10.47933/ijeir.772055

Cited By: 1

Öz

This research investigates the stress mechanics of reinforced polyester composites when exposure to a sudden impact force, using experimental and analytical methods based on impact and Linear Elastic Fracture Mechanics (LEFM) test procedures. In this study, the stress distribution around crack tip and zone for 14 test samples with geometry 210 mm x 150 mm were investigated. KII stress intensity factors, critical stress, σC, shear stress, τnt the impact energy, E and impact strength, U were determined for each specimen. The mode I fracture toughness, KIC was found to be to be 4.97 MPa.m1/2 at a critical stress of 13.53 MPa while the mode II fracture toughness, KIIC was 1.31 MPa.m1/2 at a shear stress, τnt of 3.71 MPa. The effective thickness was found to be in the range of 80-100mm at fibre volume fraction, Vf of within 0.35-0.50. This was largely found to be as result of fibre bridging and crack arrest mechanisms. This mechanism prevented crack growth direction in specimens containing woven roving not to propagate along the original direction, but change the direction to an inclined path till failure with the exception of those containing soft and hard mat in which the crack grew in the original crack direction as the stress intensity increased. During the impact test, fibre stacking sequence played a vital role, thereby making specimens containing woven roving to resist impact damage and failure, and this resulted in fibre pull-out during fracture. The stress could be seen to concentrated at the crack tip and around the loading pins on a smaller level, compared to the level at the crack tip.

Anahtar Kelimeler

Analytical Methods,, Critical Stress,, Reinforced Polyester Composites,, Shear Stress

Kaynakça

• [1]Radif, Z. S. and Ali, A. Fracture Toughness of Kenaf Mat Reinforced Polyester Composite. Pertanika Journal of Science and Technology. 99(1), 177-187, 2001.
• [2]Làszló, P. K. and George, S. S. Mechanics of Composites Structures. Cambrige University Press: New York. 20-45, 2003.
• [3]Edelugo, S. O. The Timed Response of Different Types of GRP Laminates on Exposure to Various Strenght of Alkaline and Acidic Environments. Journal of Advanced Material. 41(2), 79–87, 2009.
• [4]Dhakal, H. N., Zhang, Z. Y., Richardson, M. O. W. and Errajhi, O. A. Z. The Low Velocity Impact Response of Non-woven Hemp Fibre Reinforced Unsaturated Polyester Composites. Advanced Polymer and Composites (APC) Research Group, Department of Mechanical and Design Engineering, University of Portsmouth. Retrieved from www.elsevier.com, 2006.
• [5[Szekrényes, A. Overview on the Experimental Investigation of the Fracture Toughness in Composite Materials. Hungarian Electronic Journal of Sciences. 12, 30-38, 2007.
• [6]Williams, J. G. Linear Fracture Mechanics. Advances in Polymer Science, Springer Varlag, Berlin, Heidelberg, New York. 27, 69 – 82, 1978.
• [7]Mandel, J. A., Pack, S. C. and Tarazi, S. Micromechanical Studies of Crack Growth in Fibre Reinforced Materials. Engineering Fracture Mechanics. 16, 741-754, 1982.
• [8]Okorie, B. A. Lecture Notes on Fracture and Fracture Mechanics. Mechanical Engineering Department, University of Nigeria, Nsukka, 2010.
• [9]Parhizgar, S., Zachary, L. W. and Sun, C. T. (1982). Application of the Principle of Linear Fracture Mechanics to the Composite Materials. International Journal of Fracture Mechanics. 20, 3-15, 1982.
• [10]Janssen, M., Zuidema, J. and Wanhill, R. J. H. Fracture Mechanics. (2nd Edition). New York: Spon Press. 2004.
• [11]Garo, A. C. and Trotman C. K. Effect of Water on Fracture Toughness of Reinforced Composites. Engineering Fracture Mechanics Journal, 24, 34-42, 1980.