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2 results on '"Melo, J. D. D."'

1. Bi-angle Tape Efficiencies for Automated Tape Laying (ATL).

Author

Tsai, S. W. and Melo, J. D. D.

Subjects
ROTATING machinery, PLASTIC crystals, LAMINATED materials, ANGLES, MAGNETIC tapes
Abstract

The present work discusses many opportunities offered by bi-angle tapes for automated tape laying of composite parts. With bi-angle tape, [π/4] laminates, for example, can be produced with a [0/45] tape laid along the x-axis, followed by the same tape laid along the y-axis. The 2-axis layup is nearly three times the deposition rate over the 4-axis layup. In addition, there are many novel opportunities to engineer selections of hybrid materials, specialized off-axis angles, thick-thin ply combinations of the two ply angles, and others to achieve unique performance characteristics (like pseudo-plasticity, and tapered edges), and cost savings not possibly achieved by conventional unidirectional tape layup. The most efficient layup rate is achieved with 1-axis layup of laminates such as [0/±45], [0/±30], and those with other shallow off-axis angles. Such laminates are most practical for wings, shafts, rotors, and other 1-dimensional structures. Ultimately, bi-angle tapes can be laid by automated tape laying machines with several fold increase in the rate of deposition and flexibility that are not possible with the conventional unidirectional tape. [ABSTRACT FROM AUTHOR]

Published
2017

2. A case for Tsai's Modulus, an invariant-based approach to stiffness

Author

Sachin Shrivastava, Jocelyn M. Seng, Sung Kyu Ha, Woo Il Lee, Pedro P. Camanho, Antonio Miravete, José Daniel Diniz Melo, Aniello Riccio, Thierry Massard, Waruna Seneviratne, Henry T. Yang, Alan T. Nettles, George S. Springer, Ajit K. Roy, H. Thomas Hahn, Yasushi Miyano, A. Arteiro, Naresh Sharma, Sangwook Sihn, Klemens Rother, Robert Rainsberger, Carlos Alberto Cimini, Tong Earn Tay, Surajit Roy, Francisco K. Arakaki, Giuseppe Catalanotti, António Marques, Pranav D. Shah, Francesco Di Caprio, Arteiro, A., Sharma, N., Melo, J. D. D., Ha, S. K., Miravete, A., Miyano, Y., Massard, T., Shah, P. D., Roy, S., Rainsberger, R., Rother, K., Cimini, C., Seng, J. M., Arakaki, F. K., Tay, T. -E., Lee, W. I., Sihn, S., Springer, G. S., Roy, A., Riccio, A., Di Caprio, F., Shrivastava, S., Nettles, A. T., Catalanotti, G., Camanho, P. P., Seneviratne, W., Marques, A. T., Yang, H. T., and Hahn, H. T.

Subjects
Invariants, Composite number, 02 engineering and technology, Orthotropic material, Stiffness, 0203 mechanical engineering, medicine, Invariant (mathematics), CFRP, Scaling, Mathematics, Plane stress, Stiffness matrix, Civil and Structural Engineering, Invariant, Mathematical analysis, Analysi, Composite laminates, 021001 nanoscience & nanotechnology, 020303 mechanical engineering & transports, Ceramics and Composites, medicine.symptom, 0210 nano-technology, Analysis
Abstract

For the past six years, we have been benefiting from the discovery by Tsai and Melo (2014) that the trace of the plane stress stiffness matrix ( tr ( Q ) ) of an orthotropic composite is a fundamental and powerful scaling property of laminated composite materials. Algebraically, tr ( Q ) turns out to be a measure of the summation of the moduli of the material. It is, therefore, a material property. Additionally, since tr ( Q ) is an invariant of the stiffness tensor Q , independently of the coordinate system, the number of layers, layup sequence and loading condition (in-plane or flexural) in a laminate, if the material system remains the same, tr ( Q ) = tr ( A ∗ ) = tr ( D ∗ ) is still the same. Therefore, tr ( Q ) is the total stiffness that one can work with making it one of the most powerful and fundamental concepts discovered in the theory of composites recently. By reducing the number of variables, this concept shall simplify the design, analysis and optimization of composite laminates, thus enabling lighter, stronger and better parts. The reduced number of variables shall result in reducing the number and type of tests required for characterization of composite laminates, thus reducing bureaucratic certification burden. These effects shall enable a new era in the progress of composites in the future. For the above-mentioned reasons, it is proposed here to call this fundamental property, tr ( Q ) , as Tsai’s Modulus.

Published
2020
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