Open Access Open Access  Restricted Access Subscription Access

Performance of Additively Manufactured Chopped Fiber Composites as a Function of Porosity



Additive manufacturing (AM) of short-fiber reinforced composites are actively being considered for construction of low-cost, weight reducing alternatives to non-structural metal components. In addition AM parts are being used for rapid manufacturing of composite tooling. AM is notorious for generating parts with higher porosity than more traditional manufacturing technologies. Due to the aerospace industry’s low risk tolerance, novel material systems require comprehensive characterization of their associated manufacturing defects and the impact of defects on performance in order to receive certification. AM short fiber composites still require this analysis. Although traditional composite manufacturing methods, such as an autoclave or VARTM can produce porosity, the origin and transport of porosity has been thoroughly studied and acceptable limits for part qualification have been established to minimize the effect on performance. In AM components studies establishing the origination of porosity origin and processing defect related minimization strategies are lacking. A preliminary study on the impacts of porosity caused by print parameters such print speed, layer height, first layer height, and step-over distance has been undertaken. Direct Ink Writing (DIW) was selected for this study using an epoxy-based ink filled with clay and chopped carbon fiber. To understand performance, fracture and shear specimens were fabricated with different test parameters based on the assumed levels of porosity from screening tests. Samples were then mechanically tested using a novel in-plane shear test method and a single edge notch tension test. This study explores the processing parameter’s contribution to porosity and establishes general trends to understand the influence of porosity on performance for additively manufactured chopped fiber composites.


Full Text:



Parandoush, P., & Lin, D. (2017). A review on additive manufacturing of

polymer-fiber composites. Composite Structures, 182, 36-53.

Tekinalp, H. L., Kunc, V., Velez-Garcia, G. M., Duty, C. E., Love, L. J.,

Naskar, A. K., Blue, C. A., & Ozcan, S. (2014). Highly oriented carbon

fiber–polymer composites via additive manufacturing. Composites Science

and Technology, 105, 144-150.

Frketic, J., Dickens, T., & Ramakrishnan, S. (2017). Automated

manufacturing and processing of fiber-reinforced polymer (FRP)

composites: An additive review of contemporary and modern techniques for

advanced materials manufacturing. Additive Manufacturing, 14, 69-86.

Lewicki, J. P., Rodriguez, J. N., Zhu, C., Worsley, M. A., Wu, A. S.,

Kanarska, Y., Horn, J. D., Duoss, E. B., Ortega, J. M., Elmer, W., Hensligh,

R., Fellini, R. A., & King, M. J. (2017). 3D-printing of meso-structurally

ordered carbon fiber/polymer composites with unprecedented orthotropic

physical properties. Scientific reports, 7(1), 1-14.

Van de Werken, N., Tekinalp, H., Khanbolouki, P., Ozcan, S., Williams, A.,

& Tehrani, M. (2020). Additively manufactured carbon fiber-reinforced

composites: State of the art and perspective. Additive Manufacturing, 31,

Wang, X., Zhao, L., Fuh, J. Y. H., & Lee, H. P. (2019). Effect of porosity on

mechanical properties of 3D printed polymers: Experiments and

micromechanical modeling based on X-ray computed tomography analysis.

Polymers, 11(7), 1154.

Liu, L., Zhang, B. M., Wang, D. F., & Wu, Z. J. (2006). Effects of cure

cycles on void content and mechanical properties of composite laminates.

Composite structures, 73(3), 303-309.

Seifert, D. R., Abbott, A., & Baur, J. (2021). Topology and alignment

optimization of additively manufactured, fiber-reinforced composites.

Structural and Multidisciplinary Optimization, 63(6), 2673-2683.

Pierson, H. A., Celik, E., Abbott, A., De Jarnette, H., Gutierrez, L. S.,

Johnson, K., Koerner, H., & Baur, J. W. (2019). Mechanical properties of

printed epoxy-carbon fiber composites. Experimental Mechanics, 59(6),


Croom, B. P., Abbott, A., Kemp, J. W., Rueschhoff, L., Smieska, L., Woll,

A., Stoupin, S., & Koerner, H. (2021). Mechanics of nozzle clogging during

direct ink writing of fiber-reinforced composites. Additive Manufacturing,

, 101701.

NIST. Fractional factorial designs. Engineering Statistics


Nikishkov, Y., Airoldi, L., & Makeev, A. (2013). Measurement of voids in

composites by X-ray Computed Tomography. Composites Science and

Technology, 89, 89-97.

Nikishkov, Y., Seon, G., & Makeev, A. (2014). Structural analysis of

composites with porosity defects based on X-ray computed

tomography. Journal of Composite Materials, 48(17), 2131-2144.

Garcea, S. C., Wang, Y., & Withers, P. J. (2018). X-ray computed

tomography of polymer composites. Composites Science and

Technology, 156, 305-319.

Wang, Y., Burnett, T. L., Chai, Y., Soutis, C., Hogg, P. J., & Withers, P. J.

(2017). X-ray computed tomography study of kink bands in unidirectional

composites. Composite Structures, 160, 917-924.

Yang, Z., Ren, W., Sharma, R., McDonald, S., Mostafavi, M., Vertyagina,

Y., & Marrow, T. J. (2017). In-situ X-ray computed tomography

characterisation of 3D fracture evolution and image-based numerical

homogenisation of concrete. Cement and Concrete Composites, 75, 74-83.

Geise, L., Seifert, D. R., Abbott, A., Rapking, D., & Flores, M., (2021)

Harnessing Shape Optimization Techniques to Develop Novel Methods to

Determine Shear Properties in PMCs. Manuscript submitted for publication.

Salviato, M., Kirane, K., Ashari, S. E., Bažant, Z. P., & Cusatis, G. (2016).

Experimental and numerical investigation of intra-laminar energy

dissipation and size effect in two-dimensional textile

composites. Composites Science and Technology, 135, 67-75.

Ko, S., Yang, J., Tuttle, M. E., & Salviato, M. (2019). Effect of the platelet

size on the fracturing behavior and size effect of discontinuous fiber

composite structures. Composite Structures, 227, 111245.

Ko, S., Davey, J., Douglass, S., Yang, J., Tuttle, M. E., & Salviato, M.

(2019). Effect of the thickness on the fracturing behavior of discontinuous

fiber composite structures. Composites Part A: Applied Science and

Manufacturing, 125, 105520.

Li, W., Qiao, Y., Fenner, J., Warren, K., Salviato, M., Bažant, Z. P., &

Cusatis, G. (2021). Elastic and fracture behavior of three-dimensional plyto-

ply angle interlock woven composites: Through-thickness, size effect,

and multiaxial tests. Composites Part C: Open Access, 4, 100098.

Mahapatra, S.S., Patnaik, A. Optimization of wire electrical discharge

machining (WEDM) process parameters using Taguchi method. Int J Adv

Manuf Technol 34, 911–925 (2007).


Antony, J., & Antony, F. J. (2001). Teaching the Taguchi method to

industrial engineers. Work study.

Yang, W. H. P., & Tarng, Y. S. (1998). Design optimization of cutting

parameters for turning operations based on the Taguchi method. Journal of

materials processing technology, 84(1-3), 122-129.

ASTMD5045 Standard Test Methods for Plane-strain Fracture Toughness

and Strain Energy Release Rate of Plastic Materials (1999)

Daniel, I. M., & Ishai, O. (2007). Engineering mechanics of composite

materials. Delhi, India: Oxford University Press.

Pikely, W., Bi, Z., & Pilkey, D. (2020). Peterson’s Stress Concentration

Factors. Hoboken, NJ, USA: John Wiley & Sons.

ASTM International. D5379/D5379M-19 Standard Test Method for Shear

Properties of Composite Materials by the V-Notched Beam Method. West

Conshohocken, PA; ASTM International, 2019. doi:

Geise, L., & Flores, M. (2020). Novel Techniques for Investigating Shear of

PMCs. American Society for Composites 2020. doi: 10.12783/asc35/34871


  • There are currently no refbacks.