Seismic Performance Evaluation of RC Columns Retrofitted by 3D Textile Reinforced Mortars

The paper investigates the seismic performance of rectangular RC columns retrofitted by a newly developed 3D Textile Reinforced Mortar (TRM) panel. The 3D-TRM used in this study consists of two components: self-leveling mortar and 3D textiles. Firstly, the flexural capacity of the 3D-TRM panel was investigated through the four-point flexural test. Secondly, a total of five specimens were constructed and experimentally investigated through static cyclic loading tests with constant axial load. One specimen was a non-seismically designed column without any retrofit, while the others were strengthened with either the 3D-TRM panel or conventional Fiber Reinforced Polymer (FRP) sheets. Experimental results in terms of hysteretic behavior, ductility ratio, and energy dissipation are investigated and compared with the cases of specimens with conventional retrofitting methods and without any retrofit. The maximum lateral force, ductility, stiffness degradation, and energy dissipation of RC columns with 3D-TRM panels were significantly improved compared with the conventional RC column. Therefore, it is concluded that the proposed retrofitting method can improve the seismic performance of non-conforming RC columns.

A Hybrid Model for Predicting Steering Brake Squeal Based on Multibody Dynamics and Finite Element Methods

In recent years, the problem of automotive brake squeal during steering braking has attracted attention. Under the conditions of squealing, the loading of sprung mass is transferred, and lateral force is generated on the tire, resulting in stress and deformation of the suspension system. To predict the steering brake squeal propensity and explore its mechanism, we established a hybrid model of multibody dynamics and finite element methods to transfer the displacement values of each suspension connection point between two models. We successfully predicted the occurrence of steering brake squeal using the complex eigenvalue analysis method. Thereafter, we analyzed the interface pressure distribution between the pads and disc, and the results showed that the distribution grew uneven with an increase in the steering wheel angle. In addition, changes in the contact and restraint conditions between the pads and disc are the key mechanisms for steering brake squeal.

Age-related osteogenesis on lateral force application to rat incisor – Part III: Periodontal and periosteal bone remodeling

Objectives: This study was aimed to compare the histological pattern of bone modeling on either periodontal or periosteal side induced by lateral orthodontic tooth movement in different age groups. Material and Methods: A total of 50 male Sprague-Dawley rats (25 rats in the adult group – 52 weeks and 25 rats in the young group – 10 weeks) were utilized in this study. Each age group was classified into the control, 3 days, 7 days, 14 days, and 21 days groups (five rats in each) by the duration of experimental device application. A double-helical spring was produced using 0.014” stainless steel wire to provide 40 g lateral force to the left and right incisors. Hematoxylin-eosin staining, proliferating cell nuclear antigen (PCNA) immunohistochemical staining, fibroblast growth factor receptor 2 (FGFR2) immunohistochemical staining, and Masson trichrome staining were performed; and the slides were subject to histological examination. Results: In 7 days, active bone modeling represented by the scalloped surface was observed on the periosteal side of the crestal and middle alveolus at the pressure side in the young group, while similar changes were observed only on the crestal area in the adult group. In the young group, the number of PCNA-positive cells increased significantly on the crestal area and middle alveolus on the 3, 7, and 14 day groups, with subsequent decrease at 21 days. In the adult group, PCNA-positive cells were localized on the crestal area throughout the period. In the young group, FGFR2-positive cells were observed mainly on the crestal and middle alveolus at 3, 7, and 14 days than the control group. In the adult group, these cells appeared on the crestal and middle alveolus in the 3 days group, but mainly on the crestal area at 14 days. In the young group, FGFR2-positive cells were observed on the crestal and middle alveolus on the 3, 7, and 14 days groups more than on the control group. In the adult group, these cells appeared on the crestal and middle alveolus in the 3 days group, but mainly on the crestal area in the 14 days group. In Masson trichrome stain, an increased number of type I collagen fibers were observed after helical spring activation in both age groups. Large resorption lacunae indicating undermining bone resorption were progressively present in both young and adult groups. Conclusion: According to these results, orthodontic tooth movement may stimulate cell proliferation and differentiation primarily on the periosteal side according to progressive undermining bone resorption on the periodontal side. This response may lead to prominent bone modeling during tooth movement in the young group, compared to the relatively delayed response in the adult group.

Friction anisotropy of violet phosphorene and its surface structure direction identification

Violet phosphorene, a recently determined semiconducting two-dimensional elemental structure, is a promising electronic and optoelectronic material. The nano-tribological properties of violet phosphorene nanoflakes are essential for their micro device applications. A friction anisotropy has been demonstrated for the violet phosphorene nanoflakes by lateral force microscope due to the sub-nanorod components of violet phosphorus. The friction forces of the violet phosphorene nanoflakes have been demonstrated to be valley along sub-nano rod direction and peak across the sub-nanorod direction with a period of 180°, resulting in a fast identification of the surface structure direction of violet phosphorene. The friction of violet phosphorene nanoflakes has also been shown to increase with increasing scanning pressure. However, it is not sensitive to scanning speed or layers. The friction of the violet phosphorene nanoflakes have also been demonstrated to increase when exposure to air for hours. The friction and adhesion features of violet phosphorene nanoflakes provide valuable foundation for violet phosphorene based devices.

Conflict and Sensitivity Analysis of Articulated Vehicle Lateral Stability Based on Single-Track Model

Lateral stability is quite essential for the vehicle. For the vehicle with an articulated steering system, the vehicle load and steering system performance is quite different from the passenger car with the Ackman steering system. To investigate the influence of the tire characteristics and vehicle parameters on lateral stability, a single-track dynamic model is established based on the vehicle dynamic theory. The accuracy of the built model is validated by the field test result. The investigated parameters include the tire cornering stiffness, vehicle load, wheelbase, and speed. Based on the snaking steering maneuver, the lateral stability criteria including the yaw rate, vehicle sideslip angle, tire sideslip angle, and lateral force are calculated and compared. The sensitivity analysis of the tire and vehicle parameters on the lateral stability indicators is initiated. The results demonstrated that the parameters that affect the lateral vehicle stability the most are the load on the rear part and the tire cornering stiffness. The findings also lay a foundation for the optimization of the vehicle’s lateral stability.

Seismic Analysis and Design of Composite Shear Wall with Stiffened Steel Plate and Infilled Concrete

Several experiments are conducted to investigate the seismic behavior of composite shear walls because of their advantages compared to traditional reinforced concrete (RC) walls. However, the numerical studies are limited due to the complexities for the steel and concrete behaviors and their interaction. This paper presents a numerical study of composite shear walls with stiffened steel plates and infilled concrete (CWSC) using ABAQUS. The mechanical mechanisms of the web plate and concrete are studied. FE models are used to conduct parametric analysis to study the law of parameters on the seismic behaviour. The finite element (FE) model shows good agreement with the test results, including the hysteresis curves, failure phenomenon, ultimate strength, initial stiffness, and ductility. The web plate and concrete are the main components to resist lateral force. The web plate is found to contribute between 55% and 85% of the lateral force of wall. The corner of web plate mainly resists the vertical force, and the rest of web plate resists shear force. The concrete is separated into several columns by stiffened plates, each of which is independent and resisted vertical force. The wall thickness, steel ratio, and shear span ratio have the greatest influence on ultimate bearing capacity and elastic stiffness. The shear span ratio and axial compression ratio have the greatest influence on ductility. The test and analytical results are used to propose formulas to evaluate the ultimate strength capacity and stiffness of the composite shear wall under cyclic loading. The formulas could well predict the ultimate strength capacity reported in the literature.

RANS-BASED CFD PREDICTION OF THE HYDRODYNAMIC COEFFICIENTS OF DARPA SUBOFF GEOMETRY IN STRAIGHT-LINE AND ROTATING ARM MANOEUVRES

Computational Fluid Dynamics (CFD) simulations using Reynolds Averaged Navier-Stokes (RANS) equations are increasingly adopted as an analysis tool to predict the hydrodynamic coefficients of underwater vehicles. These simulations have shown to offer both a high degree of accuracy comparable to experimental methods and a greatly reduced computational cost compared to Large Eddy Simulation (LES) and Direct Numerical Simulation (DNS). However, one of the major challenges faced with CFD simulations is that the results can vary greatly depending on the numerical model settings. This paper uses the DARPA SUBOFF hull form undergoing straight-line and rotating arm manoeuvres at different drift angles to analyse the hydrodynamic forces and moments on the vehicle against experimental data, showing that the selection of the boundary conditions and turbulence models, and the quality of the mesh model can have a considerable and independent effect on the computational results. Comparison between the Baseline Reynolds Stress Model (BSLRSM) and Shear Stress Transport with Curvature Correction (SSTCC) were carried out for both manoeuvres, showing that with a sufficiently fine mesh, appropriate mesh treatment, and simulation conditions matching the experiments; the BSLRSM predictions offer good agreement with experimental measurements, while the SSTCC predictions are agreeable with the longitudinal force but fall outside the experimental uncertainty for both the lateral force and yawing moment.