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Jiuru Lu,Luyao Xu,Jun Hu 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.12
The aim of this study is to analysis the tensile deformation behavior of 3D printed unidirectional continuous fiber reinforced thermos-plastic composites (UD-CFRTP). Tensile experiments were performed to obtain the deformation curves and tensile properties of composites specimens. It is found that the reinforcement fiber bundles of specimens bearing the load non-synchronously. Meanwhile, with the fiber content change, the deformation form could be different. An improved micromechanical model was proposed to investigate the influence of non-synchronous phenomenon and fiber content on the deformation behavior. The fiber content is measured by the number of reinforcement fiber bundles instead of fiber volume fraction in this model. Based on this model, the deformation behavior and tensile properties of test specimens with different fiber bundles number were analyzed in detail. The analytical results about deformation behavior and tensile properties show a good agreement with experiment results.
Design and analysis of fiber placement for composite conical shell
Haojie Xu,Jiuru Lu,Kangmei Li,Jun Hu 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.3
Composite conical shells have a wide range of applications. The 3D printing technology based on FDM constrains the fibers in a plane and it is difficult to fill the fibers in the thin wall. This paper proposes a rapid prototyping method for composite materials based on curved surface fiber placement. The conical shell is divided into a series of equidistant offset surfaces. Then we designed three initial paths for fiber placement and rotated them to cover the surface of the conical shell. The resin paths are designed for filling the border layers and the gaps between the fibers. The placement process is simulated by MATLAB (R2016b) and we analyzed the parameter range, direction angle, curvature and fiber content of the three paths. When the critical parameters 0 ϕ = [0°, 42°], ξ is equal to any value and C = (0, 0.032], the corresponding initial path can reach the top of the cone shell in this study. The direction of the constant curvature curve can be designed best; when C = 0.032, the direction angle range is -90 to 90. The curvature of the geodesic path is the smallest; when 0 ϕ = 10°, the normal curvature is about 0.0001 and the geodesic curvature is equal to 0. The fiber content of the geodesic path is greatly affected by the parameter 0 ϕ , and the difference can reach 40 %. The fiber content of the linear curve is greater than 90 %. When ξ is equal to 4, the fiber content is 95 %. For the constant curvature curve, the fiber content is generally very low, about 20 %. We used a six-axis robot and a spindle to produce composite conical shell. The results show that the present design method for composite conical shell is reliable and is able to provide a useful reference for design and production of composite conical shell.