An adaptive slicing algorithm based on stereo lithography (STL) model was proposed in order to improve the forming precision of product in rapid prototyping. In the algorithm, the topological information of STL model was established, and the relationship between triangle facet and vertexes was constructed. And the adaptive slicing process based on STL model was implemented using the proposed method with combination of intersection points tracking and marking. The slicing thickness was automatically calculated according to the area differential ratio of adjacent slices.
A simple FGM object with one gradient direction is easily fabricated by the current technique; However, how to fabricate multiple gradients FGM objects is rarely mentioned by some related papers. This paper proposed a representation and fabrication approach to deal with this problem. This approach, termed as minimum fabrication cell (MFC) or allowance fabrication cell (AFC), focus on fabrication of multiple gradients FGM object. In MFC, an arbitrary 3-D model is adaptively sliced into a series of 2-D layers, and each layer is subdivided into a series of MFC or AFC along toolpath. The three linear interpolation is applied to calculate the material for each MFC or AFC, and gradient contribution ratio (GCR) is applied to calculate the material for each vertex on the MFC or AFC.
This paper introduces a calculation method of engineering insurance rate based on engineering cost. The research has great significance for promoting the development of the engineering insurance and improving the exits project risk management model. The paper uses the modification method and the maximum possible loss method to calculate the engineering insurance rate. Firstly, the paper calculates the insurance rate of part project according to engineering costs and risks of each separated project, then gets the insurance rate of unit project through the weighted average of the proportion of part project costs. Similarly, it is available to get the insurance rate of other single project. Ultimately, the overall engineering insurance rate for the engineering project can be obtained.
This paper resolves spatial RSSR mechanism in D-H coordinates to obtain its position equations. By extending Roberts-Chebyschev Theorem, it is demonstrated mathematically that RSSR mechanism possesses the same character as planer four-bar linkages in generating cognates. Considering strict requirements of spherical hinges in manufacture and assembly, this paper then addresses substitution methods of spherical hinge in RSSR mechanism, including constraining DOF of spherical pair by specific structural dimensions and replacing high pair by combinations of low pairs, while taking examples of sphere 4R mechanism, spatial orthogonal crank-rocker mechanism and spatial 6R mechanism in dobby machine. Physical kinematic simulation is done in the environment of MSC.ADAMS to validate the feasibility of spherical hinge replacement, providing guidance and reference to future design of complex spatial mechanisms.
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