Thermo-stamping shear characteristics of thermoplastics based on X-ray micro-CT

ABSTRACT

Understanding the thermo-stamping shear characteristics is not only essential to improve the forming quality of the glass fiber reinforced polypropylene (GFRPP) products but also critical to ensure their structure design reliability. Most previous studies primarily focused on the fiber yarn shear characteristics in the outer surface of the composite product, and omitted the shear angle variations of the inner layers, which might increase the failure risk to the product design. In this study, the U-shaped GFRPP rail was manufactured by the thermo-stamping process and scanned layer-by-layer through the X-ray micro-CT technology. Based on the scanning results, the differences in the shear angle variations of different layers at the same position, and within the same layer but different zones were analyzed, respectively. Finally, the effect of the temperature variation on the shear angle variation was analyzed by the simulation method. Results indicate that the interlaminar shear forces and slippages lead to the differences in shear angle variations among different layers. Intralaminar fiber yarn slippages and bending deformations caused the differences in shear angle variations within the same layer. The heat loss of the stamping molds resulted in a lower stamping temperature and further led to shear angle variation reduction.

GRAPHICAL ABSTRACT

KEYWORDS:

• Thermoplastic
• glass
• polypropylene
• temperature
• stamping
• shear
• contour
• X-CT
• simulation

Highlight

• Characterizations of the thermo-stamping shear deformation features of the U-shaped glass fiber reinforced polypropylene (GFRPP) rail layer-by-layer based on the X-ray micro-CT technology.

• The shear angle variations in different layers were different even at the same positions; the shear angle variations in the same layer but different regions of the GFRPP rail were also different.

• The heat loss of the stamping molds during the thermo-stamping process resulted in a decrease in the shear angle of the GFRPP prepreg.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Author Statement

Zhen Wang: Conceptualization, Funding acquisition, Project administration, Writing – original draft

Yisong Chen: Formal analysis, Methodology, Validation

Guohua Zhu: Funding acquisition, Supervision, Writing – review & editing

Additional information

Funding

This work is supported by the National Key Research and Development Program of China [SQ2021YFE011519], Youth Science and Technology Star Project of Shaanxi Province [2021KJXX-15], National Natural Science Foundation of China [51905042], Natural Science Foundation of Shaanxi Province [2020JQ-368], Fundamental Research Funds for the Central Universities, CHD [300102222107].