Year
Publisher
Journal
1
Institution
Institution Country
Publication Type
Field Of Study
Topics
Open Access
Language
Filter 1
Year
Publisher
Journal
1
Institution
Institution Country
Publication Type
Field Of Study
Topics
Open Access
Language
Filter 1
Export
Sort by: Relevance
Development and characterization of a magnetorheological damper with low-velocity sensitivity

Magnetorheological (MR) dampers, utilizing the unique properties of advanced materials, are extensively applied in vibration control systems. However, their performance is often compromised by the structural limitations of conventional designs. The damping force in conventional MR dampers is highly sensitive to velocity variations, primarily due to the interdependence between the piston area and the dimensions of the throttling channels, which are typically inseparable. This inherent coupling restricts the simultaneous optimization of the damping force and adjustable damping ratio, reducing the effectiveness of the magnetorheological dampers in velocity-sensitive environments. Moreover, conventional MR dampers are often characterized by complex structures and large sizes. To overcome these limitations, a novel double-rod bypass magnetorheological damper is proposed. Through the application of fluid mechanics principles and the rheological behavior of MR fluids, the velocity distribution within the throttling channel is thoroughly examined. The Bingham model is employed to establish both the velocity profile and the corresponding mechanical model, and the theoretical results align closely with experimental data, confirming the accuracy of the quasi-static model. Experimental results further demonstrate the proposed damper’s superior sensitivity to low velocities. This approach provides valuable theoretical guidance for the design of advanced MR dampers.

Read full abstract
Just Published
Model test study on the mechanical characteristics of shallowly buried covered excavation PBA station construction

The shallowly buried covered excavation PBA method is one of the new construction methods that has attracted widespread attention in the past 20 years. Understanding the deformation of strata and supporting structures is key to ensuring the safe construction of PBA stations at present. Relying on the Beijing Line 12 Beitaipingzhuang PBA subway station and based on the 1:40 model test, the production of similar materials for the model and the station excavation construction plan are introduced. According to the actual construction process of the station, the construction process of the two stations of the pile foundation and strip foundation stations are more realistic. The variations in the strata around the station and the station structure during the whole construction process are obtained. The test results show that the ground displacement of the station is most affected by the excavation of the pilot tunnel, accounting for more than two-thirds of the total displacement, and the ground within the range of 0–12 m around the station is greatly affected by the excavation disturbance during the actual construction process. By analyzing and comparing the ground displacements and the internal forces of the vertical bearing structure of the two types of stations, it is concluded that the pile foundation method is more advantageous for controlling ground displacement and the internal force of the structure. These test results improve design theory of the PBA method and are conducive to further promotion.

Read full abstract
Just Published
An in-silico protocol to predict the pelvic-status post harvesting the bone for auto-grafting procedure using finite element analysis

In bone grafting surgery, autograft, allograft, xenograft, and synthetic graft are the choices of materials used to fill the voids. Because of the risk of infection cautioned during bone grafting surgery, the bone harvested from patient’s own body is widely used to fill the damaged/diseased bone-site. In this study, the voids created post harvesting the bones from iliac-crest of a 40-years-old male patient was considered in-silico. Bone harvested in different geometric patterns by window and trapdoor techniques are considered, and a series of finite element analyses was conducted to evaluate the pelvis status pre and post extraction of bone graft under a single-leg stance loading condition. The results of the study revealed that the maximum of 20 cm3 volume of cortico-cancellous bone in the form of circular pattern harvested from the iliac-crest using a trapdoor technique as the best. To validate the result, the displacements obtained post the extraction of different volumes of cortico-cancellous bone was analyzed, and found that 20 cm3 volume of cortico-cancellous bone harvested using a circular trapdoor technique was ideal choice, considering the pelvis fragility as a major concern. The outcomes of the study can be used to noninvasively predict the pelvis status before harvesting the bone.

Read full abstract
Just Published
Experimental study and finite element analysis on the shear performance of steel-bamboo composite cellular beam

To study the influence of opening ratio on the shear performance of steel-bamboo composite cellular beams (SBCC), taking the opening size as the basic parameter, experimental research was carried out on five test beams. The failure modes and deformation characteristics of the specimens were observed, and the influence and law of the change of hole size on the shear performance of steel-bamboo composite cellular beams were analyzed. Through nonlinear finite element simulation calculation, multi-parameter analysis was carried out on the composite cellular beams, and the contribution of flanges to the shear performance of cellular composite beams was studied. The results show that the integrity of steel-bamboo composite cellular beams is good. The failure is mainly manifested as the fracture of bamboo web at the beam hole area, the buckling of section steel and the debonding and separation of steel-bamboo interface. The opening ratio has a great influence on the shear performance of steel-bamboo composite cellular beams. The thickness of bamboo flange cannot be ignored for the shear contribution of cellular beams. The shear capacity of cellular beams is shared by flanges and webs. The larger the opening ratio, the greater the shear contribution of flanges to composite cellular beams.

Read full abstract
Just Published