Abstract: A 3D printing method for an impact-resistant gradient complex part containing a hollow ceramic sphere complex, wherein the method includes the following steps: 1) designing the size and shape of the part as well as an internal layered structure; 2) providing a raw material, wherein the raw material contains a high polymer, a curing agent and hollow ceramic spheres; and 3) providing the raw material with a certain thickness according to a design, then, curing the raw material by using a heat source to form a high polymer layer containing the hollow ceramic spheres, and repeatedly printing the high polymer layer according to the design until the high polymer layer reaches the designed thickness to form the impact-resistant gradient complex part.

Abstract: A composite containing hollow ceramic spheres and a preparation method are provided. The composite includes an impact-resistant gradient complex part containing a hollow ceramic sphere complex, prepared by using a 3D printing method and a hollow ceramic sphere-high polymer complex dielectric material obtained in a blending and fusing way. The obtained composite has the characteristics of relatively low density and high strength. The impact-resistant gradient complex part is a layered complex, the composition and properties of the complex may be regulated in a direction vertical to a layer according to a design, for example, mechanical properties of the complex are transitioned from soft to hard to form gradient change by regulating the change of the composition, and meanwhile, the thickness among layers with different properties is accurately controlled as required.

Abstract: A method for characterizing complexity of rock fracture based on fractal dimension and a device thereof are provided. The method includes steps of: collecting rock fracture samples of a rock, and collecting basic parameters of the rock; determining a fractal dimension of a rock fracture morphology of the rock; calculating the fractal dimension of the rock; calculating a complexity coefficient Fc of rock fracture of the rock; and characterizing a complexity of rock fracture of the rock based on the complexity coefficient Fc of rock fracture of the rock. In the present invention, combined with the fractal geometry theory, fracture complexity coefficient of shale rocks is redefined and calculated to accurately characterize rock fracture morphology, so that characteristics of rock fracture morphology is correctly understood and affecting factors of fracture morphology is analyzed.

Abstract: A method for acquiring an opening timing of natural fracture under an in-slit temporary plugging condition and a device thereof are provided. The method includes steps of: acquiring physical parameters of stratum according to site geological data, and measuring a slit length L of a hydraulic fracture; dividing the hydraulic fracture into N unit bodies of equal length and numbering them sequentially; and dividing a total calculation time t into meter fractions of time with equal interval; calculating a width of each unit body in the hydraulic fracture at the initial time; calculating a fluid pressure in the hydraulic fracture at the k-th fraction of time; calculating a closed pressure at an entrance of the natural fracture on an upper side and a lower side of the hydraulic fracture at the k-th fraction of time; and determining whether the natural fracture is opened by a determining criteria based on the above calculation results.

Abstract: A method for acquiring an opening timing of natural fracture under an in-slit temporary plugging condition and a device thereof are provided. The method includes steps of: acquiring physical parameters of stratum according to site geological data, and measuring a slit length L of a hydraulic fracture; dividing the hydraulic fracture into N unit bodies of equal length and numbering them sequentially; and dividing a total calculation time t into in time nodes with equal interval; calculating a width of each unit body in the hydraulic fracture at the initial time; calculating a fluid pressure in the hydraulic fracture at the k-th time node; calculating a closed pressure at an entrance of the natural fracture on an upper side and a lower side of the hydraulic fracture at the k-th time node; and determining whether the natural fracture is opened by a determining criteria based on the above calculation results.

Abstract: A composite containing hollow ceramic spheres and a preparation method are provided. The composite includes an impact-resistant gradient complex part containing a hollow ceramic sphere complex, prepared by using a 3D printing method and a hollow ceramic sphere-high polymer complex dielectric material obtained in a blending and fusing way. The obtained composite has the characteristics of relatively low density and high strength. The impact-resistant gradient complex part is a layered complex, the composition and properties of the complex may be regulated in a direction vertical to a layer according to a design, for example, mechanical properties of the complex are transitioned from soft to hard to form gradient change by regulating the change of the composition, and meanwhile, the thickness among layers with different properties is accurately controlled as required.

Abstract: A method for characterizing complexity of rock fracture based on fractal dimension and a device thereof are provided. The method includes steps of: collecting rock fracture samples of a rock, and collecting basic parameters of the rock; determining a fractal dimension of a rock fracture morphology of the rock; calculating the fractal dimension of the rock; calculating a complexity coefficient Fc of rock fracture of the rock; and characterizing a complexity of rock fracture of the rock based on the complexity coefficient Fc of rock fracture of the rock. In the present invention, combined with the fractal geometry theory, fracture complexity coefficient of shale rocks is redefined and calculated to accurately characterize rock fracture morphology, so that characteristics of rock fracture morphology is correctly understood and affecting factors of fracture morphology is analyzed.