Rigid Frame Research Articles

Exploration and Innovative Research on Ideological and Political Education in Architectural Mechanics Course

The emphasis and implementation of ideological and political education in courses lie within the courses themselves, ensuring effective education through the process of course implementation and playing a role in nurturing students. This paper explores the elements of ideological and political education in the architectural mechanics course. It provides a detailed design of ideological and political education in accordance with the course content and characteristics. Additionally, innovative designs incorporating ideological elements are introduced for parts of the course. Finally, an application exploration is conducted within the sections of the course, specifically focusing on the subtopic of “rigid frames”, with the hope of providing reference value to related courses.

A novel approach to control thermal induced buckling during laser welding of battery housing through a unilateral N-2-1 fixturing principle

Battery housing (BH) in modern electric vehicles must meet demanding functional requirements. The design and geometry of the BH become intricate to prevent damage during collisions and to ensure absolute impermeability to gases and water during operation. Moreover, in the pursuit of a lightweight BH, manufacturers rely on high-strength 6xxx aluminium alloys, posing significant challenges for the welding processes. It is estimated that up to 30 m of weld length is required during the construction of battery housings including joining the lid and under-shield to the main structural frame and joining the ribs to the frame for standard vehicles. Due to the increasing use of thin sheets for lightweighting the structure, thermal-induced buckling may occur and generate critical dimensional unconformities going beyond design tolerances. This underpins the need to optimise fixturing design to control thermal-induced buckling.This paper goes beyond the state-of-the-art “N-2-1” approaches for fixturing thin and deformable parts and proposes the new principle of “unilateral N-2-1 fixturing”. The driving idea is adding unilateral restraints to the direction of thermal contraction, which ultimately causes buckling; and, keeping the direction where the thermal expansion occurs in a free state. The methodology is based on three main steps: (1) physics-based modelling of parts and fixtures using a thermo-mechanical FEA simulation; (2) calibration of the weld heat source using metallographic data; (3) validation using optical scanning technology. The methodology was demonstrated during the laser beam welding of a high-strength aluminium 6xxx thin deformable lid to a rigid high-strength 6xxx aluminium extrusion frame. Results indicated that the thermal induced buckling deformation was reduced from 15 mm, when using the state-of-the-art fixturing approach, to approximately 2 mm with the proposed methodology.

INVESTIGATION OF VERTICAL AND HORIZONTAL DEFORMATIONS OF THE PNEUMATIC SPRING OF A HIGH-SPEED MOVING VEHICLE IN THE LIMITS OF THE ARROW OF THE ARROW GEAR

The object of the research is the pneumatic spring of the second stage of the spring suspension of the high-speed rolling stock of the railway. The vertical and horizontal deformations of the pneumatic spring within the scope of the arrow translation are studied. For constructive reasons, two sections of the turnout were chosen, namely the section of the tip of the spikes and the section of the root of the spikes. In order to determine the deformations of the pneumatic spring, a methodology for its full-scale testing has been developed, which includes the use of a test rig that has a rigid metal frame on which the pneumatic spring and measuring equipment are installed. High-frequency potentiometric linear displacement sensors were used to measure vertical and horizontal deformations. In accordance with the developed complex program of field tests, records of vertical and horizontal deformations of the pneumatic spring of the high-speed rolling stock were obtained during the movement of the turn signal in the forward and opposite directions. It was found that the vertical deformations of the pneumatic spring within the range of movement by the arrow transfer in the furrow and anti-furrow directions are greater than the horizontal ones. In addition, in the opposite direction of movement of the test rig, the vertical deformations of the pneumatic spring are larger compared to the opposite direction of movement. It was established that the maximum values of the vertical deformations of the pneumatic spring are within the range of 3.14–5.05 mm in the wool direction and 4.88–5.95 mm in the anti-wool direction. The maximum values of horizontal deformations are within 1.62–2.94 mm and 1.30–2.53 mm, respectively. It was established that the average value of the vertical and horizontal deformations of the pneumatic spring of the high-speed rolling stock within the range of the arrow of the turnout is: for forward motion – 3.85 mm and 2.02 mm, for forward motion – 5,48 mm and 1.82 mm, respectively. The obtained results will make it possible to proceed to the determination of the dynamic characteristics of the pneumatic spring, and at the stage of designing high-speed rolling stock to study its dynamic indicators and traffic safety indicators under different operating conditions.

First experience of implantation of a new-generation bioresorbable stent in a young patient with coronary artery disease: a case report

Implantation of a drug-eluting stent into the area of hemodynamically significant coronary artery lesion is a generally accepted and widespread method of coronary artery disease (CAD) treatment. However, rigid metallic frame in artery is associated with disrupted vascular biomechanics and neointimal proliferation in response to foreign material. These processes can lead to restenosis and/or late thrombosis of the implanted stent and, as a consequence, to the recurrence of CAD symptoms, as well as to adverse cardiovascular events. One of the options for solving the above problems is the implantation of bioresorbable stents. This technique already has an evidence base and is increasingly being introduced into routine clinical practice in certain groups of patients. The article presents a case of successful balloon angioplasty and stenting of the right coronary artery with a new-generation bioresorbable stent in a young patient with CAD.

Research on bridge safety early warning method based on strain energy theory and health monitoring data

Bridges are technology-intensive and heavily invested permanent infrastructure. After completion and opening to traffic, bridge structures are easy to be affected by factors such as traffic load and atmospheric environment. Therefore, it is necessary to do safety warning and evaluation of bridges, especially the abnormal behavior in the early stages of bridge operation. In this research paper, a large-span continuous rigid frame bridge installed with the health monitoring system (HMS), of which a large amount of health monitoring data are collected by the HMS, is used as an example, and then a bridge safety early warning method is proposed when the bridge is during early operating period. First of all, the research finding that the internal stress of the prototype bridge obeys normal distribution through statistical analysis is used; next, we deduce that the strain energy inside the prototype bridge is subject to the Non-central Chi-square distribution combined with the strain energy and statistical theories; in the end, the key probability density distribution function of strain energy and its parameters are derived by using the key stress distribution function of the high performance concrete C50 strength grade used in the prototype bridge. The method recommended in this paper is conducive to the formulation of bridge preventive maintenance strategies.

Synchronization phenomenon in a vibration system with three rigid frames driven by two co-rotating unbalanced rotors

Synchronization phenomenon in a vibration system with three rigid frames driven by two co-rotating unbalanced rotors

Experimental and Numerical Evaluation of Calcium-Silicate-Based Mineral Foam for Blast Mitigation

Cellular materials such as aluminum and polyurethane foams are recognized for their effectiveness in energy absorption. They commonly serve as crushable cores in sacrificial cladding for blast mitigation purposes. This study delves into the effectiveness of autoclaved aerated concrete (AAC), a lightweight, porous material known for its energy-absorbing properties as a crushable core in sacrificial cladding. The experimental set-up features a rigid frame made of steel measuring 1000 × 1000 × 15 mm3 with a central square opening (300 × 300 mm2) holding a 2 mm thick aluminum plate representing the structure. The dynamic response of the aluminum plate is captured using two high-speed cameras arranged in a stereoscopic configuration. Three-dimensional digital image correlation is used to compute the transient deformation fields. Blast loading is achieved by detonating 20 g of C4 explosive set at 250 mm from the plate’s center. The study assesses the mineral foam’s absorption capacity by comparing out-of-plane displacement and mean permanent deformation of the aluminum plate with and without the protective solution. Six foam configurations (A to F) are tested experimentally and numerically, varying in the foam’s free space for expansion relative to its total volume. Results show positive protective effects, with configuration F reducing maximum deflection by at least 30% and configuration C by up to 70%. Foam configuration influences energy dissipation, with an optimal lateral surface-to-volume ratio (ζ) enhancing protective effects, although excessive ζ leads to non-uniform foam crushing. To address the influence of front skin deformability, a non-deformable front skin has been adopted. The latter demonstrates an increased effectiveness of the sacrificial cladding, particularly for ζ values above the optimal value obtained when using a deformable front skin. Notably, using a non-deformable front skin increases maximum deflection reduction and foam energy absorption by up to approximately 30%.

High-Efficiency Finite Element Model Updating of Bridge Structure Using a Novel Physics-Guided Neural Network

An accurate finite element model (FEM) plays a critical role in the structural damage identification. However, due to the existence of the uncertainties, such as material properties and modeling errors, it always exists some gaps between the analytical FEM and experimental structure. While an artificial neural network (ANN)-based model updating methods have been widely adopted to narrow the gap and obtain a baseline FEM, it still faces inaccurate results and fails to meet the physical law. In this regard, the study proposes a novel physics-based loss function inspired by modal sensitivity analysis and incorporates it into the residual neural network, thereby forming a novel physics-guided neural network (PGNN) method. The mapping relationship between the input of structural responses and output of model updating variables is constrained to retain its physical meaning by guiding the training process instead of pure data association, which aims to improve the accuracy of the ANN-based method and achieve accurate and high-efficiency model updating. An experimental example of a continuous rigid frame bridge is adopted to verify the feasibility of the proposed method. Additionally, other common model updating methods, including moth-flame optimization and regularization method, are used to make a comparison. The noise-robustness of the proposed method is investigated as well. Compared to the existing method, the results illustrate that the proposed PGNN method can achieve better model updating and good noise-robustness under high uncertainties, which means the introduction of the physics-based loss function significantly enhances the parameters updating ability of the neural network. The proposed method exhibits high efficiency and promising potential for large-scale bridge structure model updating.

Biodiversity associated with a coralligenous build-up off Sicily (Ionian Sea)

Coralligenous is one of the most important habitats of the Mediterranean Sea hosting a very high biodiversity that, however, has not been fully investigated yet. The paper addressed the study of the biodiversity of a coralligenous bioconstruction collected at a depth of 36.7 m off Marzamemi (SE Sicily, Ionian Sea). The species diversity, composition and structure of the main associated taxonomic groups were investigated in order to identify possible differences between the communities of the hard framework (mainly built by calcified corallinales) and the canopy cover. The examined build-up showed significant species diversity for almost all groups. Bryozoans were the most diversified group and, together with foraminifers, also the most abundant both on the canopy and the frame. Further groups showed high species diversity (except for serpulids) and total abundance (except for molluscs) on the canopy rather than on the frame. Due to their different nature and microenvironmental parameters, the canopy and the frame hosted different communities. Besides juvenile specimens, the canopy mostly hosted unmineralized and weakly mineralized, small-sized, short-lived species well adapted to living on ephemeral and flexible substrates. On the contrary, the rigid and persistent frame mostly hosted highly mineralized, large, long-lived species, which usually contributed to the building and strengthening of the bioconstruction. Unlike mapping and monitoring, a thorough description of coralligenous biodiversity requires accurate naked eye and microscopical analysis assisted by SEM investigation due to the small size and cryptic behaviour of several species.

Numerical investigation and seismic performance evaluation of an innovative prefabricated structural system

This paper focuses on an innovative structural system with separated gravity and lateral resisting systems (SGLR system), which is suitable for multi-story prefabricated buildings and demonstrates different seismic performance from the traditional rigid frame system (RF system). Elaborate three-dimensional (3D) finite element models for RF and SGLR systems are established and verified by test results. Based on the numerical models, the load-displacement relationship, force mechanism, energy dissipation capacity, local buckling, and stress and strain distribution of SGLR system are investigated in detail in comparison with RF system. In order to conduct the seismic performance evaluation, four groups of RF and SGLR substructures are designed with different lateral stiffness. Pushover analysis and response spectrum analysis are carried out, and safety factors are calculated on the basis of the incremental N2 method. It is indicated that SGLR system has lower loading capacity, smaller safety margin but larger deformation capability than RF system with the same lateral stiffness. Considering that the inter-story drift ratio is a common design index, more stringent design requirements should be proposed for SGLR system to obtain seismic performance equivalent to that of RF system.

Study on seismic performance of a novel connection for exterior wall panels

In order to avoid the damage of the external wall panel and connecting joints caused by the incompatibility between the steel structure and the external wall panel under earthquake loads, as well as to control the interaction between the structure and wall panel to ensure favorable impacts on the main structure, a new connection for external wall panel is proposed. This connection combines the features of the sliding connection and the energy dissipating connection. To investigate the deformation behavior, failure modes, and energy dissipation capacity of the connection, a total of ten specimens with different parameters were designed for cyclic loading. The results indicate that the new connection dissipates energy through bending plastic deformation and pull-bending plastic deformation of the side plate, demonstrating excellent deformation and energy dissipation capacity with noticeable post-yield strengthening effect. Additionally, the effects of different geometric parameters on the initial stiffness, yield load, bearing capacity and hysteretic properties of the connections are also analyzed. Finally, based on the theoretical model of the space rigid frame, the calculation formula of the characteristic parameters at elastic stage of the joint is proposed by the assumptions of ignoring torsion, axial and shear deformation, which is validated by the test results and finite element simulation.

Hydrodynamic response analysis of the aquaculture net under the combined action of irregular waves and currents

ABSTRACT The hydrodynamic response of fishing nets is crucial in aquaculture. During service, due to severe sea states and collisions with large fish, potentially resulting in net damage. Analyzing this damage is complex due to the large number of net meshes. This study establishes a mathematical model of the net system under wave-current coupling based on the rigid-body kinematics and the lumped-mass method. An analysis was conducted to investigate how various environmental conditions and types of damage affect net deformation and force. Results indicate that maximum force occurs at the connections to the rigid frame and the midpoint of the net. Among various types of net damage, the nodes motion increased exclusively around the periphery of the damaged area, while the netting twine force significantly decreased only in the direction of the damage. Notably, damage to the upper net has the greatest impact on both netting twine force and deformation.

Design of Mold Flipper in an Effort to Improve The Efficiency of Mold Maintenance Process

Molding is a production process by forming raw materials using a rigid frame or model used in the manufacturing industry to mold materials called a mold. Injection molding is a technique in the manufacturing industry for molding thermoplastic materials. Thermoplasctic materials commonly molded with Injection Molding techniques are Polystyrene, Acrylonitrile Butadiene Styrene (ABS), PMMA (Polymethyl Methacrylatic) and others. The purpose of this research is to design and build a flipper molding tool for an easier and more efficient mold maintenance process. This research uses descriptive methods. Data is taken through direct observation and through reference books both from companies and websites and journals related to the report material. The data obtained was analyzed using descriptive analysis. it is found that the material used in the work is Carbon Steel (S45C). The process of making Flipper Clamps Mold has several stages, namely the Design Making Process, Material Selection Process, Cutting Process, Milling Process, Grinding Process, Drilling Process, Welding Process, and Assembly Process. With this Flipper Clamping tool, it is hoped that it can make it easier for operators to maintain and repair molds, because the previous mechanism requires two operators to flip molds that weigh more than 200 kg, now they only need to flip by turning the lever of this tool.

Studies on multi-frequency synchronization of two pairs of counter-rotating exciters in a split drive double-body vibrating system

In this article, the multi-frequency synchronization characteristics and stability of a split drive double-body vibrating system with two rigid frames (RFs), driven by two pairs of counter-rotating exciters symmetrically mounted on two different RFs, are investigated in detail by theory, numeric, and simulation. Based on Lagrange’s equations, the differential equations of motion of the system are deduced. The theoretical criteria for implementing foundation frequency, double-frequency, and triple-frequency synchronization of two pairs of exciters are obtained by applying the asymptotic method. The stability criteria of the synchronous states are derived according to the Routh–Hurwitz criterion. Then, the synchronous and stable regions and stability ability coefficients of the system are analyzed qualitatively by numeric. The simulations are conducted to verify the validity of the theoretical methods used and the correctness of corresponding theoretical results. It is shown that, under the precondition of realizing the multi-frequency synchronization, the ideal working point of the system should be set in Region I to obtain the larger and more stable superposition vibration amplitude between two RFs in engineering. The present work can provide theory guidance for designing new types of vibrating equipment with two different driving frequencies.

Experimental investigations on the flexural behavior of UHPC wet joints for UHPC light-weight rigid frame arch bridges

Wet joints are critical parts of prefabricated ultra-high-performance concrete (UHPC) light-weight rigid frame arch bridges (LWRFAGs), so their mechanical behavior is important to the structural design and applications of these arch bridges. To explore suitable joint configurations and reinforcement arrangements for connecting UHPC components or arch ribs of a practical UHPC LWRFAG, this paper experimentally investigated flexural behavior of several prefabricated UHPC joint beams with various kinds of wet joints through four-point bending tests. Firstly, four different UHPC joint beams with different joint configurations were designed, including (i) vertical joint; (ii) rhombus joint; (iii) vertical joint with top and bottom strips; and (iv) rhombus joint with top and bottom strips, and their flexural performance were compared with a complete UHPC beam. The experimental results revealed that UHPC joint beam employing the rhombus joint with top and bottom strips exhibited superior flexural behavior and cracking resistance among four UHPC joint beams. Subsequently, to achieve optimal and robust joint configurations, bending performance of one complete UHPC beam and three large-scale UHPC joint beams with rhombus joints but different reinforcement arrangements were experimentally studied. It is observed that the beam with the welded twist reinforcements (specimen V-4) shown optimal flexural performance and cracking resistance. Finally, to explore the load transfer mechanism and effects of reinforcement parameters on flexural behavior of specimen V-4, the parametric studies were comprehensively performed using finite element analyses (FEA). This study could serve as both the experimental and theoretical reference for flexural design of UHPC beams with the rhombus wet joints.

Synchronization and stability of a vibrating system with two rigid frames driven by two groups of coaxial rotating exciters

This article explores the synchronization, stability and motion characteristics of the generalized dynamical model with two rigid frames (RFs) driven by two groups (even number) of coaxial rotating exciters. In light of this system’s generalized coordinates, we use Lagrange’s equations to derive the generalized differential equation of motion. The responses of absolute and relative motion of the generalized system are obtained using the transfer function method. The synchronization and stability criteria of multiple exciters are derived using the average method and Hamilton’s theory, respectively. Taking a dynamical model driven by two pairs of exciters as an example, the localized studies of generalized results are carried out. The stable synchronous solutions for phase differences and excitation frequency, the stability ability coefficient curves and the response curves are graphically presented considering the effect of two crucial dimensionless parameters on the stable synchronous states. The simulation results of the specific system are obtained using the fourth-order Runge-Kutta algorithms and compared with the numerical qualitative analysis results to reveal the high consistency between them and clarify the used methods’ effectiveness. The strength of this work stems from its use in the field of high power and large scale self-synchronization vibrating machines.

Soft Gripping Fingers Made of Multi-Stacked Dielectric Elastomer Actuators with Backbone Strategy.

Soft grippers, a rapidly growing subfield of soft robotics, utilize compliant and flexible materials capable of conforming to various shapes. This feature enables them to exert gentle yet, if required, strong gripping forces. In this study, we elaborate on the material selection and fabrication process of gripping fingers based on the dielectric elastomer actuation technique. We study the effects of mixing the silicone elastomer with a silicone thinner on the performance of the actuators. Inspired by nature, where the motion of end-effectors such as soft limbs or fingers is, in many cases, directed by a stiff skeleton, we utilize backbones for translating the planar actuation into a bending motion. Thus, the finger does not need any rigid frame or pre-stretch, as in many other DEA approaches. The idea and function of the backbone strategy are demonstrated by finite element method simulations with COMSOL Multiphysics® 6.5. The paper describes the full methodology from material choice and characterization, design, and simulation to characterization to enable future developments based on our approach. Finally, we present the performance of these actuators in a gripper demonstrator setup. The developed actuators bend up to 68.3° against gravity, and the gripper fingers hold up to 10.3 g against gravity under an actuation voltage of 8 kV.

Numerical model for time-dependent cracking and deflection of large-span concrete bridge structures

A new computational framework is proposed to analyse the simultaneous occurrence of multiple physical processes affecting the long-term behavior of large-scale concrete structures. Relying on the additivity of small strain, the framework comprehensively takes the nonlinearity of concrete creep, cyclic creep induced by traffic load, concrete shrinkage, concrete cracking, normal-strength steel rebars and prestressing strands relaxation into account, and other physical processes are further imagined. The algorithm is implemented with Abaqus/Standard with the aid of several user-supplied subroutines. The implicit time integration scheme is deemed appropriate for large-scale structures. The framework is systematically validated by several classical experimental results. Finally, a three-dimensional study of a three-span continuous rigid frame bridge with 270 m main span is performed. Comparison between the experimental and numerical results further reveals the contributions of various potential influencing factors. The proposed model shows promise for predicting the time-dependent performance of large-scale reinforcement concrete (RC) structures.

Feasibility of intentional bioprosthetic valve fracture in the tricuspid position.

Transcatheter tricuspid valve-in-valve (ViV) replacement has yielded good hemodynamic outcomes in the treatment of dysfunctional bioprosthetic valves (BPVs). Intentional fracture of certain rigid BPV frames, if feasible, allows a larger implanted valve when compared with implant into an unfractured BPV. There remains limited data on the feasibility of tricuspid valve frame fracture. Evaluate the feasibility of transcatheter tricuspid ViV replatement with fracture of the underlying BPV ring. An international multicenter registry of tricuspid ViV replacement with intentional tricuspid valve frame fracture was created. Demographic data along with procedural characteristics, outcomes, and follow-up data were collected. Comparison was made to the pre- and post-ViV replacement with fracture of the tricuspid valve frame conditions. Ten patients from six centers were included with a median age and weight of 29 years and 67.3 kg respectively. Tricuspid valve frame fracture was performed using a median balloon diameter 3 mm (IQR 3-5) larger than the true inner diameter (ID). The final ID was a mean of 1.5 mm (95% CI: 0.35, 2.64: p < 0.05), and median 1.1 mm (0.5, 2.1) larger than the reported true ID of the surgical BPV after ViV replacement. The mean tricuspid inflow gradient by echocardiogram decreased by 6.65 mmHg (95% CI: 4.14, 9.15: p < 0.001). All procedures were without complication, specifically there was no heart block, pericardial effusion, or right coronary disruption. Intentional tricuspid valve frame fracture with tricuspid ViV replacement is feasible and can increase the valve orifice potentially reducing the risk of ViV patient prosthesis mismatch and is not associated with significant complications.

Activist subtitling narrates liminoid experiences countering ISIS post-Arab Spring—Daya alTaseh and The Bigh daddy Show

This paper examines activist subtitling practices in light of the two sociological concepts of narrativity and liminality. With particular focus on online contemporary activist communities that counter extremism, subtitling is studied as part of the cultural liminoid practices that produce and disseminate alternative narratives challenging the rigid frames of global jihadism. Launched as reactions to the repercussions of the Arab Spring and the establishment of the so-called Islamic State in Iraq and Syria, ضايعة الطاسة Daya alTaseh and ذا بيج دادي شوو The Bigh daddy Show are two activist online media initiatives that spread counter-jihadist narratives in Arabic subtitled in English. The study attempts to investigate the narratives mediated in the subtitles and their reflections of liminality. The subtitling in both initiatives is scrutinised and compared using a two-fold theoretical framework combining the socio-narrative theory in translation studies and theories on activist translation. Guided by this framework, the paper applies a descriptive qualitative analysis to data collected from observations and interviews. The data analysis reveals the distinct liminoid stories of Daya alTasehand The Bigh daddy Show as narrated in the English subtitles, pinpointing the similarities and differences between them. User interaction with both initiatives is also highlighted as a contributor to the development of the subtitling process.