Effect of Short-chopped Thermoplastic Prepreg Sheet Dimensions on the Mechanical Properties of Molded Components

LIU Yuehai; FU Rao; YAN Hongbin; WANG Qi; MA Sai; WANG Fuji

doi:10.3969/j.issn.1674-6457.2025.11.005

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Journal of Netshape Forming Engineering ›› 2025, Vol. 17 ›› Issue (11) : 58-67. DOI: 10.3969/j.issn.1674-6457.2025.11.005

Intelligent Processing of Advanced Materials

Effect of Short-chopped Thermoplastic Prepreg Sheet Dimensions on the Mechanical Properties of Molded Components

LIU Yuehai, FU Rao, YAN Hongbin, WANG Qi^*, MA Sai, WANG Fuji

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Abstract

The work aims to investigate chopped carbon fiber reinforced polyamide 6 (CF/PA6) composites to systematically examine the effect of sheet aspect ratio on mechanical properties, so as to propose an optimal selection methodology for prepreg sheet dimensions. Four types of CF/PA6 sheets with aspect ratios of 1∶1, 2∶1, 4∶1, and 6∶1 were prepared. Test specimens were fabricated through an exhaust-assisted compression molding process. Microstructural defects such as pores and out-of-plane fiber waviness were quantitatively characterized with optical microscopy and micro-CT, while tensile tests were conducted to evaluate macro-mechanical properties. With the increasing aspect ratio, the uniformity of pore distribution decreased, and the number of large pores (≥10¹⁵ nm³) increased. Meanwhile, out-of-plane fiber waviness became more severe, with the average waviness ratio and waviness angle increasing by 122% and 140%, respectively. Both tensile strength and modulus initially increased and then decreased as the aspect ratio increased, peaking at an aspect ratio of 2∶1. The aspect ratio of chopped prepreg sheets affects the mechanical properties of composites by influencing the evolution of microscopic defects and the continuity of stress transfer pathways. An aspect ratio of 2∶1 achieves an optimal balance between efficient stress transmission and defect suppression, providing critical insight for performance optimization and process design of complex structural components.

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chopped prepreg sheets / compression molding / CF/PA6 composites / microstructural defects / mechanical properties

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LIU Yuehai, FU Rao, YAN Hongbin, WANG Qi, MA Sai, WANG Fuji. Effect of Short-chopped Thermoplastic Prepreg Sheet Dimensions on the Mechanical Properties of Molded Components[J]. Journal of Netshape Forming Engineering. 2025, 17(11): 58-67 https://doi.org/10.3969/j.issn.1674-6457.2025.11.005

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