3D Printed Rotatable Wind Chime Modeling From A Simple Polygon

3D printing is a new manufacturing technology that constructs objects by stacking materials layer by layer.It has brought changes in production and manufacturing processes.Compared to traditional subtractive manufacturing method,this manufacturing process has promoted the research and development of digital 3D technology effectively.3D printing is maturing rapidly with advances in materials and mechanism,and has begun to flourish in various design disciplines,such as product design,medical device design,entertainment and fashion design etcGenerally speaking,there are two ways of modeling:using computer-aided design tools and scanning the model to reconstruct.Due to the high cost of these two methods,people prefer to use modeling methods with less sacrifice such as rotation and stitching.These methods not only have a small modeling cost,but also have a wide range of application scenarios.For arbitrary polygons,there will be some limitations when the multi-layered rotating model generated by traditional offset or scaling methods.Inspire by the structures of rotatable wind chimes,we propose a method for modeling a 3D printable,collision free,multi-layer rotatable model from an arbitrary simple polygonGiven a simple polygon,we compute a series of internal contours and the corresponding rotating axis,such that each contour can rotate around its axis with no collision of the space.We first calculate internal contours and use the sweep surface polygon to determine the collision state.The axis composes of two points in the polygon contour simplified by filtering points.Then we calculate an optimal axis by using the sweep surface polygon.The second step is to optimize the position of the inner layer.This part aim to make sure that the current layer can rotate freely without collision by affine transformation.To simplify the operation,we find the oriented bounding box of the current sweep surface polygon and use its oriented bounding box to replace the polygon.At the same time,we simplify the initial polygon and randomly scatter point in the initial polygon as the center point.We first optimize the position of the center point,then we optimize the rotation angle to calculate the largest oriented bounding box.The rectangle is horizontal when the oriented bounding box is in the initial state,and its rotation range is[-90,90°].Next,we draw two lines that are perpendicular to each other through the current center point and set three isometric points on these two lines.We scale the rectangle until the rectangle is completely covered by the polygon or less than the current optimal solution.We apply the transformation matrix to the current layer to get a layer with the largest area and compute all layers of the internal polygon iterativelyWe stretched and widened the contour structure,and add T-shaped joints to connect the layers of the rotating model.The T-shaped structure not only acts as connecting two adjacent layers,but also acts as the rotation axis of the inner layer.We construct the printable 3D model by adding joints along with each axis.The model can be fabricated in a planar state with high efficiency and accuracy,in one piece without assembly.Experiments show that our results are of both rotatable properties and aesthetics,and can be 3D printed with high efficiency.The future work includes two aspects.On the one hand,we will design and use different contraction forms and methods to generate compressible rotating models;on the other hand,we are going to design different joint structures.