This application relates to a method for analyzing the dynamic characteristics of carbon composite materials. In the method, a specimen for a specific carbon fiber orientation is prepared and a modal test is performed on the specimen to obtain data and analyze the characteristics of the specimen on the basis of the data. To solve conventional carbon composite material dynamic characteristic analysis methods for carbon composite materials, the proposed method can determine the orientation of carbon fiber orientation exhibiting desired dynamic characteristics by predicting various system parameters at the state of designing, i.e., before the manufacture of a carbon composite material. Especially, the method predicts system parameters such as structural stiffness and viscous damping coefficient which are very sensitive to the orientation of carbon fiber, using only data of a single reference orientation, and reflects the prediction results on the design of a carbon composite material.

This application relates to a method for analyzing the dynamic characteristics of carbon composite materials. In the method, a specimen for a specific carbon fiber orientation is prepared and a modal test is performed on the specimen to obtain data and analyze the characteristics of the specimen on the basis of the data. To solve conventional carbon composite material dynamic characteristic analysis methods for carbon composite materials, the proposed method can determine the orientation of carbon fiber orientation exhibiting desired dynamic characteristics by predicting various system parameters at the state of designing, i.e., before the manufacture of a carbon composite material. Especially, the method predicts system parameters such as structural stiffness and viscous damping coefficient which are very sensitive to the orientation of carbon fiber, using only data of a single reference orientation, and reflects the prediction results on the design of a carbon composite material.

A loading pad to be attached to a specimen to apply a load to the specimen includes: a back skin on which the load is applied; an elastic body that is provided between the back skin and the specimen; and an inserted member that is provided between the elastic body and the specimen. The back skin, the elastic body, and the inserted member are bonded as one unit. The inserted member is less rigid than the specimen, and is more rigid than the elastic body.

A loading pad to be attached to a specimen to apply a load to the specimen includes: a back skin on which the load is applied; an elastic body that is provided between the back skin and the specimen; and an inserted member that is provided between the elastic body and the specimen. The back skin, the elastic body, and the inserted member are bonded as one unit. The inserted member is less rigid than the specimen, and is more rigid than the elastic body.

Methods are provided for joint performance validation and include preparing a coupon from a blank by bending the blank to have a pair of legs disposed at substantially ninety degrees relative to each other. Another coupon is prepared by forming an opening in a segment of another blank and bending the segment approximately ninety degrees. The segment is disposed adjacent an end of the second blank. A test sample is prepared by joining the coupons together at a joint with a leg attached to the segment approximately at a center of the leg. The test sample is subjected to a force test to generate data for the performance validation.

Methods are provided for joint performance validation and include preparing a coupon from a blank by bending the blank to have a pair of legs disposed at substantially ninety degrees relative to each other. Another coupon is prepared by forming an opening in a segment of another blank and bending the segment approximately ninety degrees. The segment is disposed adjacent an end of the second blank. A test sample is prepared by joining the coupons together at a joint with a leg attached to the segment approximately at a center of the leg. The test sample is subjected to a force test to generate data for the performance validation.

A device and a method for testing tensile resistance of multiple-row grouped pillars in an inclined goaf are provided. The bottoms of stands of the device are connected with a testing machine base, and the tops of the stands of the device are connected with a transverse frame; an upper slideable clamping seat and a lower slideable clamping seat are semi-cylindrical blocks, multiple lower loading jaws that are positioned to have a same central line are arranged on the lower slideable clamping seat, each of the lower loading jaws is opposite to a corresponding one of the upper loading jaws, the lower loading jaws are welded to the lower slideable clamping sea to test the tensile resistance of samples together; the upper part of the upper slideable clamping seat is connected with an upper pressure disk, and the lower slideable clamping seat is connected with a lower pressure disk.

A device and a method for testing tensile resistance of multiple-row grouped pillars in an inclined goaf are provided. The bottoms of stands of the device are connected with a testing machine base, and the tops of the stands of the device are connected with a transverse frame; an upper slideable clamping seat and a lower slideable clamping seat are semi-cylindrical blocks, multiple lower loading jaws that are positioned to have a same central line are arranged on the lower slideable clamping seat, each of the lower loading jaws is opposite to a corresponding one of the upper loading jaws, the lower loading jaws are welded to the lower slideable clamping sea to test the tensile resistance of samples together; the upper part of the upper slideable clamping seat is connected with an upper pressure disk, and the lower slideable clamping seat is connected with a lower pressure disk.

The present invention discloses a quantitative evaluation method for sensitivity of welding transverse cold cracks in a typical joint of a jacket, including following steps: S1, performing macroscopic analysis, metallographic analysis, fracture analysis and hardness analysis on cracks of a failed component to obtain main causes of cold crack failure; and S2, designing and processing a dedicated sample, and performing rigid restraint crack tests on the dedicated sample at different preheating temperatures to obtain a cracking/non-cracking critical restraint stress σ1cr of the sample. According to the method, a rigid restraint crack test is applied to evaluation of sensitivity of welding transverse cracks, so that external restraint conditions borne by a welding joint can be accurately simulated, a stress state of the welding joint in an actual working condition can be truly reflected, the overall evaluation precision is greatly improved, and a foundation is laid for accurately evaluating sensitivity of welding cold cracks in a tube joint. Furthermore, a welding technology (base material, welding material, welding process and restraint level) is designed to restrain cold cracks from cracking, and the method has important theoretical significance and engineering value.

The vertical counterforce loading device includes a concrete support member, four transfer components, four connection components, a vertical force transmission component and a load test soil layer. The concrete support member is formed by pouring and concreting below the load test soil layer. The four transfer components are divided into two groups to be symmetrically and parallelly anchored in the concrete support member. The vertical force transmission component includes a load plate, a jack, a primary beam and a secondary beam arranged in sequence from bottom to top. The load plate is installed on the load test soil layer. Two secondary beams are connected crosswise to both ends of the primary beam, where end portions of the secondary beams are respectively connected to second ends of the connection components through reinforcement components. The device can improve work efficiency, reduce construction costs and improve safety.