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When steel fiber and PVA fiber produced in China and PVA fiber made in Japan are prepared according to the appropriate proportions, the mechanical properties of hybrid fiber-reinforced cementitious composites (HFRCC) are better, which is beneficial to cost control and has wide application prospects. The effects of the volume content of steel fibers and the volume substitution rate of PVA fibers on the tensile strength, compressive strength, and flexural strength of HFRCC were analyzed using the factor optimization method and principal component analysis (PCA). Through the principal component analysis of HFRCC, a mathematical model for comprehensive performance evaluation was established, and a multi-objective optimization was carried out. The results show that compared with the matrix, the tensile strength, compressive strength, and flexural strength of concrete increase significantly when the volume content of steel fibers is 0.2–0.4% and the volume substitution rate of domestically produced PVA fibers in China or PVA fibers produced in Japan is 50–100%. The maximum cost reduction is 88.25%, and the strength index of HFRCC can reach the optimum; the weights of each factor on the performance of HFRCC were obtained through mathematical statistics. Combined with a variable correlation analysis, these indicators should be noted when optimizing the performance of HFRCC. The research results can provide a basis for the preparation of HFRCC. [ABSTRACT FROM AUTHOR]

Recognizing the anisotropy of mechanical property transfer between carbon fiber reinforced polymer (CFRP) layers, a unidirectional reduced‐order model (UROM) is proposed to comprehensively express the mechanical properties of each layer. A crucial focus is on effectively analyzing the real‐time mechanical properties of CFRP specimens, particularly in accurately identifying and predicting the interlaminar mechanical states of anisotropic CFRP laminated specimens. Moreover, the multi fidelity surrogate (MFS) is employed to replace the computationally intensive model, amalgamating high‐fidelity sensor data with low‐fidelity data obtained from the UROM. The UROM MFS is used to reduce the amount of data in the same layer of CFRP laminates, while preserving the characteristics between different layers and preserving the interlaminar information of CFRP laminates. Finally, the stress prediction results of the UROM MFS and the unreduced MFS model were compared and analyzed. The real‐time response speed of the u‐ROM MFS digital twin (DT) model was increased by 658%. The UROM MFS DT model effectively captures the mechanical properties of each layer of CFRP laminates, enables quick calculation of model parameters, and provides accurate predictions. Highlights: First, the interlayer mechanical property of CFRP is analyzed with the combined application of experimental data, DT model, and UROM MFS.Second, MFS is employed to merge high‐fidelity sensor data of CFPR laminate with low‐fidelity data obtained from UROM.Third, the digital twin framework for CFPR laminate with high response speed and calculation accuracy is proposed. [ABSTRACT FROM AUTHOR]

The static and dynamic performance of the machine tool directly affects the machining accuracy, dimensional stability, and service reliability. In order to analyze the mechanical performances of a precision horizontal machine center, a finite element (FE) model was established using ANSYS software. The deformation curve of the guide rail was obtained through static analysis of nine different working conditions. The dynamic characteristics of the precision horizontal machining center were obtained through dynamic analysis. And modal hammer impact tests were conducted on the machining center to verify the simulation results. The results showed that the maximum deformation of the guide rail was 0.0134 mm (situation 6), and the experimental measurement values of the first five natural frequencies of the whole machine were 96 Hz, 116 Hz, 198 Hz, 213 Hz, and 229 Hz. And it was found that adding a column structure can significantly improve the dynamic characteristics of precision horizontal machining centers. This study provides a theoretical basis and technical support for the improvement and optimization of the dynamic and static performance of machine tools. [ABSTRACT FROM AUTHOR]

Copyright of Guangdong Architecture Civil Engineering is the property of Guangdong Architecture Civil Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of China Petroleum Machinery is the property of China Petroleum Machinery Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

When steel fiber and PVA fiber produced in China and PVA fiber made in Japan are prepared according to the appropriate proportions, the mechanical properties of hybrid fiber-reinforced cementitious composites (HFRCC) are better, which is beneficial to cost control and has wide application prospects. The effects of the volume content of steel fibers and the volume substitution rate of PVA fibers on the tensile strength, compressive strength, and flexural strength of HFRCC were analyzed using the factor optimization method and principal component analysis (PCA). Through the principal component analysis of HFRCC, a mathematical model for comprehensive performance evaluation was established, and a multi-objective optimization was carried out. The results show that compared with the matrix, the tensile strength, compressive strength, and flexural strength of concrete increase significantly when the volume content of steel fibers is 0.2–0.4% and the volume substitution rate of domestically produced PVA fibers in China or PVA fibers produced in Japan is 50–100%. The maximum cost reduction is 88.25%, and the strength index of HFRCC can reach the optimum; the weights of each factor on the performance of HFRCC were obtained through mathematical statistics. Combined with a variable correlation analysis, these indicators should be noted when optimizing the performance of HFRCC. The research results can provide a basis for the preparation of HFRCC.

The existing large inflatable membrane structure is complex in structure and takes a long time to be extended. In this paper, an air-ribbed skeleton membrane structure is proposed to meet the requirement of camp and emergency tents needing to be set up quickly and easily. Ten single-arch air ribs are arranged side by side to support the tarpaulin, and wind ropes are added to the end and side faces of the tarpaulin to remain stable. The finite element model of the air-ribbed skeleton membrane structure is established to analyze the stress and the displacement of the membrane structure under combined wind and snow loads. The maximum displacement (439.4 mm) and maximum stress (29.94 MPa) are both within the safe standard. The stress and the displacement of the membrane structure in the wind load case is affected by the angle of the wind. The value of maximum stress and displacement at the wind angle of 90° are both lower than those at 0° and 45° in the wind load case. It is advisable to align the site layout of the membrane structure at the wind angle of 90°. The effect of the angle of wind ropes on the stress and displacement of the membrane structure is also studied. The maximum stress and displacement in the case when the angle of wind rope is 30° is smaller than those in the case when the angle of wind ropes is 45°. It is recommended that the wind rope should be laid at 30° to reinforce the membrane structure. [ABSTRACT FROM AUTHOR]

Embedded systems have more and more designs and applications in wearable health monitoring and the Internet of Things (IoT) recently. In this work, a battery-free human breathing monitoring system based on soft polyvinylidene fluoride (PVDF) piezoelectric thin film for pressure sensing and solid lead zirconate titanate (PZT) pads for powering energy harvest is designed and fabricated. Proper material and structure are chosen by mechanical analysis to fabricate the systems. Then the device is used to measure the real breathing signal while studying (the memory test is used to represent the study procedure). The breathing frequency and intensity data are extracted and used in correction analysis with the testing score. And the results show that peaceful, slow, and deep breathing will have a positive influence on the testing score. This study opens the mind to combine engineering designed devices with educational research, showing the broad application of mechanical and electronic systems. [ABSTRACT FROM AUTHOR]

One of the primary challenges in developing bone substitutes is to create scaffolds with mechanical properties that closely mimic those of regenerated tissue. Scaffolds that mimic the structure of natural cancellous bone are believed to have better environmental adaptability. In this study, we used the porosity and thickness of pig cancellous bone as biomimetic design parameters, and porosity and structural shape as differential indicators, to design a biomimetic bone beam scaffold. The mechanical properties of the designed bone beam model were tested using the finite element method (FEM). PCL/β-TCP porous scaffolds were prepared using the FDM method, and their mechanical properties were tested. The FEM simulation results were compared and validated, and the effects of porosity and pore shape on the mechanical properties were analyzed. The results of this study indicate that the PCL/β-TCP scaffold, prepared using FDM 3D printing technology for cancellous bone tissue engineering, has excellent integrity and stability. Predicting the structural stability using FEM is effective. The triangle pore structure has the most stability in both simulations and tests, followed by the rectangle and honeycomb shapes, and the diamond structure has the worst stability. Therefore, adjusting the porosity and pore shape can change the mechanical properties of the composite scaffold to meet the mechanical requirements of customized tissue engineering. [ABSTRACT FROM AUTHOR]

In the spin-off acceleration stage during high-speed rotation in space, the deployable arm of the space gravity simulation device must withstand a large axial centrifugal force and a driving torque. In this paper, a large-scale high-speed rotating deployable arm is proposed, and the relevant characteristics during the rotation process are analyzed. A new driving mode of towed deployment is proposed that can lead to the rapid and efficient deployment of a large-scale deployable arm. First, an optimized configuration of a deployable arm is proposed. Second, the deployment driving process of the deployable arm under several different drag driving modes is simulated and analyzed, and a comparative analysis is performed to select a simple and reliable drag deployment driving scheme. Then, the effects of various disturbances on the posture of the deployable arm during the rotation process are explored, guiding the posture control of the deployable arm. Finally, a 10 m four-unit prototype is developed for the stiffness and rotation tests, which verify that the theoretical analysis in this paper is correct. [ABSTRACT FROM AUTHOR]

Copyright of Ordnance Industry Automation is the property of Editorial Board for Ordnance Industry Automation and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The existing large inflatable membrane structure is complex in structure and takes a long time to be extended. In this paper, an air-ribbed skeleton membrane structure is proposed to meet the requirement of camp and emergency tents needing to be set up quickly and easily. Ten single-arch air ribs are arranged side by side to support the tarpaulin, and wind ropes are added to the end and side faces of the tarpaulin to remain stable. The finite element model of the air-ribbed skeleton membrane structure is established to analyze the stress and the displacement of the membrane structure under combined wind and snow loads. The maximum displacement (439.4 mm) and maximum stress (29.94 MPa) are both within the safe standard. The stress and the displacement of the membrane structure in the wind load case is affected by the angle of the wind. The value of maximum stress and displacement at the wind angle of 90° are both lower than those at 0° and 45° in the wind load case. It is advisable to align the site layout of the membrane structure at the wind angle of 90°. The effect of the angle of wind ropes on the stress and displacement of the membrane structure is also studied. The maximum stress and displacement in the case when the angle of wind rope is 30° is smaller than those in the case when the angle of wind ropes is 45°. It is recommended that the wind rope should be laid at 30° to reinforce the membrane structure.

Coarse-grained soils have been commonly employed as filling materials in engineering projects, and comprehending the mechanical properties of these soils is crucial for ensuring project safety. Currently, artificial intelligence (AI) plays a significant role in advancing these fields. However, the inherent lack of stability and interpretability of AI models constrains their potential for providing substantial assistance. To solve these shortcomings, this study investigates the mechanical properties of coarse-grained soils and proposes an approach that integrates a stable learning module with neural networks to enhance the stability of an AI model. The proposed method addresses the challenge of relaxing the strong assumption of independent and identically distributed (i.i.d.) data. In addition, it improves the stability of the prediction of a relationship between the deviatoric stress and axial strain. The proposed method is verified by experiments. The experimental results confirm that the proposed method performs well on real-world data samples that deviate from the i.i.d. assumption. Moreover, the proposed method enhances the interpretability of the AI model and facilitates the identification of crucial features for assessing the strength behavior of coarse-grained soils. This feature of interpretability is invaluable for practical engineering applications. [ABSTRACT FROM AUTHOR]

Taking a new type of special threaded drill pipe joint as the research object, a 3D nonlinear finite element model of the double-shoulder tool joint (DSJ) including the engage and retract groove structure is established by considering the factors of structural asymmetry and contact of each engaging surface. ABAQUS/Explicit finite element method (FEM) is used to study the stress and contact pressure distribution characteristics of the critical structure of DSJ under make-up torque and axial tension. The accuracy of the finite element model was verified by combining with a full-scale physical test, and the connection strength and sealing performance of DSJ are evaluated. The results show that the stress concentration occurs at the key structure of DSJ under the make-up torque. The geometry size and structural discontinuity at the transition fillet of the double-shoulder structure have a significant effect on the stress and contact pressure distribution on the shoulder. Under axial tension, the stress level and stress concentration area of the whole joint and the key structure change, especially in the thread section. The sealing performance on the shoulder decreases significant, while that of the thread section increases slightly. The test results are consistent with the finite element analysis findings, and this joint shows good mechanical properties, which can meet the design requirements of drilling tool manufacturers and provide data support for its optimal design and application. • Evaluation of mechanical properties of a new type of special threaded tool joint. • A nonlinear 3D double-shoulder tool joint finite element model was established. • Complex loads have a significant effect on stress distribution at key structures. • This new tool joint provides better connection strength and sealing performance. [ABSTRACT FROM AUTHOR]

One of the primary challenges in developing bone substitutes is to create scaffolds with mechanical properties that closely mimic those of regenerated tissue. Scaffolds that mimic the structure of natural cancellous bone are believed to have better environmental adaptability. In this study, we used the porosity and thickness of pig cancellous bone as biomimetic design parameters, and porosity and structural shape as differential indicators, to design a biomimetic bone beam scaffold. The mechanical properties of the designed bone beam model were tested using the finite element method (FEM). PCL/β-TCP porous scaffolds were prepared using the FDM method, and their mechanical properties were tested. The FEM simulation results were compared and validated, and the effects of porosity and pore shape on the mechanical properties were analyzed. The results of this study indicate that the PCL/β-TCP scaffold, prepared using FDM 3D printing technology for cancellous bone tissue engineering, has excellent integrity and stability. Predicting the structural stability using FEM is effective. The triangle pore structure has the most stability in both simulations and tests, followed by the rectangle and honeycomb shapes, and the diamond structure has the worst stability. Therefore, adjusting the porosity and pore shape can change the mechanical properties of the composite scaffold to meet the mechanical requirements of customized tissue engineering.

In the spin-off acceleration stage during high-speed rotation in space, the deployable arm of the space gravity simulation device must withstand a large axial centrifugal force and a driving torque. In this paper, a large-scale high-speed rotating deployable arm is proposed, and the relevant characteristics during the rotation process are analyzed. A new driving mode of towed deployment is proposed that can lead to the rapid and efficient deployment of a large-scale deployable arm. First, an optimized configuration of a deployable arm is proposed. Second, the deployment driving process of the deployable arm under several different drag driving modes is simulated and analyzed, and a comparative analysis is performed to select a simple and reliable drag deployment driving scheme. Then, the effects of various disturbances on the posture of the deployable arm during the rotation process are explored, guiding the posture control of the deployable arm. Finally, a 10 m four-unit prototype is developed for the stiffness and rotation tests, which verify that the theoretical analysis in this paper is correct.

To explore the harm of carpenter bee nests to timber buildings, an eave purlin of Wu's house, the seventh batch of national key cultural relics in China, was taken as the research object. A CT (computed tomography) device was used to collect the projection data of wood components, and VGSTUDIO MAX3.2 software was used to reconstruct multiple transverse sections, radial sections, tangential sections, and 3D (three-dimensional) images of an eave purlin. The results showed that carpenter bees eroded on a timber building randomly, but they usually nested along the length of eave purlin. The wood in the middle of an eave purlin is more vulnerable to carpenter bees than the end. Carpenter bee nests are usually not connected, and the volume of nests accounts for 3% to 4% of the eave purlin. The eave purlin is applied with an orientation and a torsion force. The position of the maximum hot spots of the stress occurs at holes and the large cracks, indicating that carpenter bee nests have a great impact on the mechanical properties of timber buildings. The research results of this paper provide reference for the safety evaluation and preventive protection of timber buildings. [ABSTRACT FROM AUTHOR]

Maintenance for nuclear fusion vessel is crucial, yet it faces great difficulty due to the complex internal physical and geometric conditions. Since the limitation on inherent strength, load, size, etc, a manipulator robot can only complete very limited tasks. Robotic arm systems for remote operation such as JET and MPD can carry certain tools to complete a variety of operating tasks, but it is difficult to achieve the system which is very complex. Therefore, if the inherent idea of using a single robot to complete the specified functions can change, it is possible to make the problems simpler and easier to solve by adding auxiliary robots working together with the robotic arm systems to complete the assigned tasks. Under the above background, based on the deeply analyzing and refining the functional requirements of the vessel operation robot, proceeding from the perspective of ability to move and carry a certain operating device, this paper presents a wormlike creeping mobile robot walking on the V-shaped circular slot inside a nuclear fusion vessel such as EAST (Experimental Advanced Superconducting Tokamak). We have designed and implemented the principle prototype of the robot which has chain structure with n (n ≥2) creeping units. Each creeping unit is of three-part structure, which consists of fore segment, mid segment and back segment connected by bidirectional universal joint. The fore and back segments stretch the paws to contact the surface of V-shaped slot, while the mid segment realizes the overall movement of robot. In order to evaluate the design and implementation of the mobile robot platform, functional analysis is devoted to modules of robot. Especially for the requirements of walking stability on the V-shaped slot, creeping gait planning is analyzed to construct a multi-axis coordinating movement control scheme for creeping motion. Finally, by using the simulated EAST nuclear fusion vessel, the principle prototype is tested, and the preliminary evaluation of its functional index and related technical parameters is carried out. The experimental results show that the principle prototype of the robot can achieve stable walking on the V-shaped circular slot at the bottom of the nuclear fusion vessel, and it has a certain ability to carry equipments. [ABSTRACT FROM AUTHOR]