Integration 3D printing of bionic continuous carbon fiber reinforced resin composite

ABS resin which was used for FDM 3D printing was purchased from Sanweicube Co., Ltd, China. Continuous carbon fiber with specification of 1 K (consisted of one thousand monoradicular continuous carbon fiber) was purchased from Yixing Siweiqi Carbon Fiber Products Co., Ltd, China. ABS and continuous carbon fiber were used as received. The fresh mantis shrimps were purchased from the aquatic product market of Changchun, China. After removing from noumenon, the spearer propodus of mantis shrimp was washed and dried at room temperature for 3 days.

3D printing of bionic continuous carbon fiber reinforced ABS resin composite was prepared via the self-built 3D printing machine. Figure 1 shows the proximal extrusion structure and preparation mechanism. The proximal extrusion structure was composed of extruder, heating head and subuliform nozzle with diameter of 0.8 mm. ABS resin was squeezed into the heating head with temperature of 240 °C via the driving gears. After squeezing into heating head, the continuous carbon fiber was wrapped by ABS resin. Under the sequential squeeze of ABS resin, the continuous carbon fiber wrapped ABS resin was extruded to the printing platform. The printing precision was 0.1 mm. The mass fraction of continuous carbon fiber in ABS matrix was about 10 wt.%. The sample structure was designed by SolidWorks. The corresponding STL file was used for 3D printing of composites. After slicing via the Slic3r software39 offered by Alessandro Ranellucci, the G cord file was obtained. Attributed to the specific structure design of bionic composites, the G cord file was self-written. The software of Repetier-Host was used to preview and modified G cord files. In order to prove the validities of bionic structure design and role of continuous carbon fiber, the bionic composite, the ABS/CF composite with paralleled continuous carbon fiber arrangement and pure ABS matrix were prepared, respectively.

Zoom In Zoom Out Reset image size

2.3.1. Microstructure

2.3.2. Tensile strength

The tensile strength sample with dimension of 75 mm × 10 mm × 2 mm (length × width × thickness) was 3D printed directly. The stress and strain were calculated by the following equations.

$$\begin{eqnarray}&&\sigma =\displaystyle \frac{{\rm{F}}}{{\rm{A}}}.\end{eqnarray} \tag{ 1 }$$

$$\begin{eqnarray}&&\varepsilon =\displaystyle \frac{1-{1}_{0}}{{1}_{0}}.\end{eqnarray} \tag{ 2 }$$

where σ and ε represented stress and strain, respectively. F was maximum force. A was sectional area of sample. l and l₀ were actual and original length, respectively. The universal mechanical machine (Model C43, MTS Criterion, USA) with constant loading rate was 1 mm min⁻¹ was used. The average value of the stress and strain were obtained from five individual tests. The tensile fracture morphology was observed via SEM to analyse the anti tensile mechanism.

2.3.3. Impact toughness

The impact resistance sample with dimension of 75 mm × 10 mm × 2 mm (length × width × thickness) was obtained directly via 3D printing. The impact toughness was calculated by the following equation.

$$\begin{eqnarray}&&{\rm{a}}=\displaystyle \frac{A}{bh}.\end{eqnarray} \tag{ 3 }$$

where a represented impact toughness. A was impact work. b and h were width and thickness of sample. A can be obtained from impact testing machine with pendulum of 7.5 J (Model JC-50D, Beijing Times Peak Technology Co., Ltd, China). The loading span for impact toughness tests was 40 mm. The average value of the impact toughness was obtained from five individual tests. The impact fracture morphology was observed via SEM to analyse the anti impact mechanism.

As shown in figure 2(a), the mantis shrimp propodus was composed of many compact mineralized chitin-protein fibers, which exhibited layered structure and rotated around the normal axis of the spearer propodus [20]. The layered spiral structure played an important role in mechanical strength of spearer propodus. Inspired by the microstructure characteristics of mantis shrimp propodus, the bionic layered spiral structure which was used for bionic composite design was constructed, as shown in figure 2(b). The bionic structure model was divided into 10 layers, which consisted of many cylindrical entities in specific layers. With the increase of height, the layers constituted of cylindrical entities spiralled from 0° to 45°, forming the bionic layered spiral structure. The bionic structure model reappeared the microstructure characteristics of mantis shrimp propodus, providing structure design reference for bionic continuous carbon fiber reinforced ABS resin composite. Based on 3D printing technology demands, the designed 3D printing bionic composite model with layered spiral structure was exhibited in figure 2(c). The 3D printing structure model realized the application of bionic structure model in sample structure design, which guided the 3D preparation of bionic composite.

Zoom In Zoom Out Reset image size

According to bionic structure model with layered spiral structure, the bionic continuous carbon fiber reinforced ABS resin composite was successfully 3D printed, as shown in figure 3(a). The morphology of bionic composite in figure 3(a) exhibited the 45° arrangement direction of continuous carbon fiber, which was similar to bionic structure model in figure 2(b). The continuous carbon fiber in ABS/CF composite was parallel to the length direction of sample. The ABS/CF composite and pure ABS matrix were used to disclose the effectiveness of bionic design. Compared with the ABS/CF composite, the bionic composite realized the bionic arrangement of continuous carbon fiber in ABS matrix, as shown in figure 3(b). The continuous carbon fiber with fascicled state exhibited specific arrangement direction and coated with ABS matrix. Besides effectiveness arrangement direction, the excellent bonding state between continuous carbon fiber and ABS matrix proved the feasibility of 3D printing and bionic layered spiral structure, which built material base of mechanical strength test.

Zoom In Zoom Out Reset image size

In order to investigate the effect of bionic layered spiral structure, mechanical properties including tensile strength and impact toughness of bionic composite, ABS/CF composite and pure ABS matrix were conducted, as shown in figure 4. The stress values of ABS matrix, ABS/CF composite and bionic composite were 30.15 MPa, 28.98 MPa and 31.99 MPa, respectively. The strain values of ABS matrix, ABS/CF composite and bionic composite were 25.24%, 18.67% and 18.59%, respectively. Compared with ABS matrix, the continuous carbon fiber without surface treatment resulted in the decreased stress of ABS/CF composite. The reinforcing role of continuous carbon fiber was restricted in the ABS/CF composite. But, under same material and preparation method, the existence of bionic layered spiral structure led to the higher stress of bionic composite than that of ABS matrix and ABS/CF composite. Attributed to the existence of continuous carbon fiber, the strain values of ABS/CF composite and bionic composite were reduced. Under the reinforcing role of arrangement direction of continuous carbon fiber in ABS/CF composite, the impact toughness was higher than that of ABS matrix. The existence of bionic arrangement of continuous carbon fiber led to the highest impact toughness, as shown in figure 4(b). The mechanical properties in figure 4 exhibited the effectiveness of bionic layered spiral structure. Moreover, the integration 3D printing of continuous carbon fiber and ABS matrix provided an efficient and feasible preparation method for the realization of bionic design.

Zoom In Zoom Out Reset image size

The bionic composite owned relatively high mechanical strength, building application base for engineering materials. In order to disclose the mechanical mechanisms of bionic composite, the tensile fracture surface and impact fracture surface were observed. As shown in figure 5(a), many continuous carbon fiber and holes resulted from pull-out of carbon fibers existed on the rough tensile fracture surface. From the magnification of tensile fracture surface in figure 5(b), it can be found that the continuous fascicled carbon fibers were tensile failure and were exposed to ABS matrix surface. The residual ABS resin on continuous carbon fiber indicated the relatively high bonding strength between ABS resin and reinforcement. Moreover, the interlaced continuous carbon fiber layer arrangement was similar to the microstructure characteristic of mantis shrimp propodus, reappearing the bionic layered spiral structure characteristics. Figure 5(c) exhibited the mechanical mechanisms including fracture and pull-out of continuous carbon fibers in bionic composite for enhancing tensile strength. Compared with the tensile fracture surface, the impact fracture surface also exhibited rough morphology and fractured continuous carbon fibers in figure 5(d). But, the length of continuous carbon fibers which exposed on impact fracture surface was lower than that on tensile fracture surface. In the magnification of impact fracture surface, ABS resin also existed on the pull-out continuous carbon fibers, which indicated the relatively high bonding strength between matrix and reinforcement. Different fascicled continuous carbon fibers intersected on impact fracture surface, exhibiting the effective arrangement of bionic structure. The fracture and pull-out of continuous carbon fibers in bionic composite were also the main mechanical mechanisms of bionic composites. Based on analysis of tensile and impact fracture surface, bionic composite exhibited relatively high mechanical strength via the mechanisms of fracture and pull-out of continuous carbon fibers. The bionic layered spiral structure enhanced the mechanical strength of bionic composite and maintained the reinforcing properties of continuous carbon fibers in ABS resin matrix. Inspired by structure characteristics of bionic model with high mechanical properties. Integration 3D printing of ABS resin and continuous carbon fiber provided an effective new preparation method for application of carbon fiber reinforced thermoplastic resin composite.

Zoom In Zoom Out Reset image size