Measuring the Mechanical Properties of Glass Fiber Reinforcement Polymer Composite Laminates Obtained by Different Fabrication Processes

Summary

This paper describes a fabrication process for fiber-reinforced polymer matrix composite laminates obtained using the wet hand lay-up/vacuum bag method.

Abstract

The traditional wet hand lay-up process (WL) has been widely applied in the manufacturing of fiber composite laminates. However, due insufficiency in the forming pressure, the mass fraction of fiber is reduced and lots of air bubbles are trapped inside, resulting in low-quality laminates (low stiffness and strength). The wet hand lay-up/vacuum bag (WLVB) process for the fabrication of composite laminates is based on the traditional wet hand lay-up process, using a vacuum bag to remove air bubbles and provide pressure, and then carrying out the heating and curing process.

Compared with the traditional hand lay-up process, laminates manufactured by the WLVB process show superior mechanical properties, including better strength and stiffness, higher fiber volume fraction, and lower void volume fraction, which are all benefits for composite laminates. This process is completely manual, and it is greatly influenced by the skills of the preparation personnel. Therefore, the products are prone to defects such as voids and uneven thickness, leading to unstable qualities and mechanical properties of the laminate. Hence, it is necessary to finely describe the WLVB process, finely control steps, and quantify material ratios, in order to ensure the mechanical properties of laminates.

This paper describes the meticulous process of the WLVB process for preparing woven plain patterned glass fiber reinforcement composite laminates (GFRPs). The fiber volume content of laminates was calculated using the formula method, and the calculated results showed that the fiber volume content of WL laminates was 42.04%, while that of WLVB laminates was 57.82%, increasing by 15.78%. The mechanical properties of the laminates were characterized using tensile and impact tests. The experimental results revealed that with the WLVB process, the strength and modulus of the laminates were enhanced by 17.4% and 16.35%, respectively, and the specific absorbed energy was increased by 19.48%.

Introduction

Fiber reinforced polymer composite (FRP) is a type of high-strength material manufactured by mixing fiber reinforcement and polymer matrixes^1,2,3. It is widely used in the aerospace^4,5,6, construction^7,8, automotive⁹, and marine^10,11 industries due to its low density, high specific stiffness and strength, fatigue properties, and excellent corro....

Protocol

1. Material preparation

1. Cut eight pieces of 300 mm x 300 mm woven glass fiber fabric with scissors. Tape the cut first to prevent the fiber filaments from falling off.
   NOTE: Wear a mask and gloves to prevent finger pricking and filament inhalation when cutting the fabric. Not only the woven glass fiber fabric, but unidirectional fabric and other types of fiber, such as carbon fiber and aramid fiber, are also available.
2. Weigh out 260 g of epoxy resin and 78 g of hardener according to the mass ratio of 10:3.
   ​NOTE: The ratio of fiber fabric and resin system is recommended to be 360 g of epoxy resin system per sq....

Results

Table 1 shows the fiber volume fraction, average thickness, and fabrication process of the samples. The G8-WLVB and G8-WL represent the laminates consisting of 8-ply glass fabric manufactured by wet hand lay-up with and without the vacuum bag process, respectively. Obviously, with the vacuum bag assistance, laminates have an increase of 15.78% in fiber volume fraction, as well as an reduction of 16.27% in average thickness.

Strain-stress curves obtained by the tensile test of .......

Discussion

This paper focuses on the two different fabrication processes for the hand lay-up method with low cost. Therefore, two fabrication processes were selected to be carefully described in this paper, which are simpler, easier to master, lower in investment cost, and suitable for production with material modification in laboratories and small-scale factories. During the cure of laminates, high consolidation pressure plays an important role in manufacturing laminates with high quality. The adoption of the traditional WL proces.......

Materials

Name	Company	Catalog Number	Comments
breather fabric	Easy composites	BR180
drop-weight impact testing machine	Instron	9340
Epoxy matrix	Axson Technologies	5015/5015
glass fiber	Weihai Guangwei Composites	W-9311
non-porous release film	Easy composites	R240
Peel ply	Sino Composite	CVP200
perforated released film	Easy composites	R120-P3
test machine	ZwickRoell	250kN
vacuum film	Easy composites	GVB200