Relative Deflection Research Articles

A shear effect in a bending non-standard I-beam under uniformly distributed load

The paper is devoted to the analytical study of the bending problem of a simply supported or clamped non-standard I-beam under a uniformly distributed load. The cross-sectional shape of this beam, as a three-part structure, is analytically described. The purpose of this research is to present a detailed analytical model of this beam, considering the shear effect and its influence on the beam's deflection. This model is formulated according to linear elastic theory, and the deformation of a planar cross-section after the bending of this beam due to the shear effect is determined. Based on the principle of stationary potential energy, two differential equations of equilibrium are obtained. These equations are analytically solved, and the dimensionless shear effect function and the relative deflection of this beam are derived. Consequently, the maximum dimensionless relative deflection and the dimensionless coefficient of the shear effect are determined. Exemplary calculations are carried out for three selected non-standard I-beams of different lengths, demonstrating a significant influence of the shear effect on the deflections of short beams, especially clamped beams.

Fracturing above longwall panels and the associated changes in hydraulic conductivity

Information from conditions observed when mining overlying seams have been combined with interpretations of surface subsidence surveys and physical models to develop a fracture model for subsidence above longwall panels. This model proposes zones of high hydraulic conductivity around the sides of collapsed goaf as an alternative to the existing layer models. In the absence of a thick spanning unit, fracturing can extend upwards from the longwall extraction to a height equal to twice the width of each longwall panel. An indication of whether fracturing has extended to the surface is if the relative deflection across the extraction exceeds about 0.4-0.6m. A simple method is proposed to estimate hydraulic conductivity values from measured vertical subsidence and the spacing of joints opened by the subsidence. The method produces hydraulic conductivity values that are consistent with reports of mine water inflows and impacts on shallow aquifers.

Mechanical Response of Hot-Mixed Epoxy Asphalt Concrete Steel Deck Pavement Under Thermal and Load

In recent years, fatigue cracking in orthotropic steel bridge deck pavements has become a significant concern, so the investigation of the mechanical response of the pavement layer has become a central focus in pavement structure design. This experiment subjected a full-scale specimen to a constant amplitude dynamic load of 60 kN to 300 kN over 2 million cycles. Throughout the testing, a circulating water bath elevated the temperature of the pavement layer from 15 °C to 50 °C. Key locations were monitored for strain and deflection data, facilitating an investigation into the mechanical response of the epoxy asphalt pavement system under the effects of temperature and load. The results indicate that the maximum transverse strain at the bottom of the steel deck occurs at the U-rib weld aligned with the load center, reaching 190% of the initial loading strain. Meanwhile, the maximum transverse strain on the pavement surface is observed at the U-rib weld adjacent to the loaded area, measuring 167% of the initial strain. The maximum longitudinal strain is lower than the maximum transverse strain. In the load zone, the longitudinal strain between the U-ribs exceeds that at the U-rib weld. Both transverse strain and relative deflection increase as the load intensifies. The relationship between transverse strain and applied load is characterized by an exponential function, while deflection exhibits a cubic relationship with the applied load. Elevated temperatures also contribute to increased transverse strains at both the bottom of the steel deck and the pavement surface, following an exponential trend. Relative deflection is primarily influenced by the applied load and remains relatively unaffected by temperature variations. When accounting for the coupling of load and temperature, the maximum transverse strains at both the bottom of the steel deck and the pavement surface can be modeled as an exponential function of the independent variables: load and temperature.

Ride comfort analysis on vehicle using a new nonlinear isolator for the seat suspension

Abstract Seat suspension plays a crucial role in attenuating low-frequency vibrations and improving overall riding comfort. This paper proposes a new nonlinear isolator for seat suspension using a novel high-static-low-dynamic stiffness with sliding mass inertia (HSLDS-SMI). The HSLDS-SMI seat suspension includes a negative stiffness structure and two secondary sliding masses. A multi-degree-of-freedom (MDOF) dynamic model is developed, comprising a simplified quarter-car model and a biodynamic human model. Various isolation performance indices are then considered and analyzed under two different road excitations using numerical methods. The impact of the sliding mass on ride comfort is examined under both road profiles. The findings demonstrate that the HSLDS-SMI seat suspension performs better than its two counterparts while ensuring the relative suspension deflection remains within acceptable limits.

Application of von-Karman model for laminated composite singly curved shells with non-uniform boundary conditions

The industrial applications of singly curved shells significantly increased in modern engineering structures and several of those have non-uniform boundary conditions. A detailed relative performance study for the non-uniformly restricted shells can popularize their use further among practicing engineers. The literature review confirms that there is dearth of research studies in this area. This paper aims to fill up that void. A finite element code of C0 continuity combining von-Karman strains, first order shear deformation theory and eight noded curved elements is proposed. Wide variety of shell problems are solved for different boundary conditions, laminations, radii of curvatures, thickness, and plan dimensions. Relative nondimensional deflections and fundamental frequencies are studied for varying boundaries. It is concluded that although the performances of shells are comparable for different boundaries, the shells with CCCC edges offer better performances. These shells should have longer span along the arch direction, a symmetric 16°/-16°/-16°/16° laminate, side/thickness = 100, and radius of curvature/plan = 0.75 to achieve minimum deflection and maximum fundamental frequency.

The influence of shear surface quality on the mechanical properties of long-span prestressed continuous rigid-frame bridge

PurposeThe long-span continuous rigid-frame bridges are commonly constructed by the section-by-section symmetrical balance suspension casting method. The deflection of these bridges is increasing over time. Wet joints are a typical construction feature of continuous rigid-frame bridges and will affect their integrity. To investigate the sensitivity of shear surface quality on the mechanical properties of long-span prestressed continuous rigid-frame bridges, a large serviced bridge is selected for analysis.Design/methodology/approachIts shear surface is examined and classified using the damage measuring method, and four levels are determined statistically based on the core sample integrity, cracking length and cracking depth. Based on the shear-friction theory of the shear surface, a 3D solid element-based finite element model of the selected bridge is established, taking into account factors such as damage location, damage number and damage of the shear surface. The simulated results on the stress distribution of the local segment, the shear surface opening and the beam deflection are extracted and analyzed.FindingsThe findings indicate that the main factors affecting the ultimate shear stress and shear strength of the shear surface are size, shear reinforcements, normal stress and friction performance of the shear surface. The connection strength of a single or a few shear surfaces decreases but with little effect on the local stress. Cracking and opening mainly occur at the 1/4 span. Compared with the rigid “Tie” connection, the mid-span deflection of the main span increases by 25.03% and the relative deflection of the section near the shear surface increases by 99.89%. However, when there are penetrating cracks and openings in the shear surface at the 1/2 span, compared with the 1/4 span position, the mid-span deflection of the main span and the relative deflection of the cross-section increase by 4.50%. The deflection of the main span increases with the failure of the shear surface.Originality/valueThese conclusions can guide the analysis of deflection development in long-span prestressed continuous rigid-frame bridges.

An Angle-Oriented Approach to Transferring Speech to Gesture for Highly Anthropomorphized Embodied Conversational Agents

Realistic co-speech gestures are important to anthropomorphize ECAs, as nonverbal behavior improves expressiveness of their speech greatly. However, the existing approaches to generating co-speech gestures with sufficient details (including fingers, etc.) in 3D scenarios are indeed rare. Additionally, they hardly address the problem of abnormal gestures, temporal–spatial coherence and diversity of gesture sequences comprehensively. To handle abnormal gesture issues, we put forward an angle conversion method to remove body part length from the original in-the-wild video dataset via transferring coordinates of human upper body key points into relative deflection angles and pitch angles. We also propose a neural network called HARP with encoder–decoder architecture to transfer MFCC featured speech audio into aforementioned angles on the basis of CNN and LSTM. The angles then can be rendered as corresponding co-speech gestures. Compared with the other latest approaches, the co-speech gestures generated by HARP are proved to be almost as good as the real person, i.e., they have strong temporal–spatial coherence, diversity, persuasiveness and credibility. Our approach puts finer control on co-speech gestures than most of the existing works by handling all key points of the human upper body. It is more feasible for industrial application, since HARP can be adaptive to any human upper body model. All related code and evidence videos of HARP can be accessed at https://github.com/drrobincroft/HARP .

НЕСУЩАЯ СПОСОБНОСТЬ БАЛОК ТАВРОВОГО ПРОФИЛЯ С ПОЛКОЙ ИЗ ВЫСОКОПРОЧНОГО БЕТОНА И ПРОДОЛЬНОЙ АРМАТУРОЙ КЛАССА А500С

Experimental and numerical studies of the bearing capacity and deformation of T-beams with a flange made of high-strength concrete and longitudinal reinforcement of class A500C with a web made of concrete of ordinary strength were carried out on prototypes of beams and numerical models. The beams being tested are considered at different percentages of reinforcement. The calculation scheme of the beams corresponded to a four-point bend. As a result of experimental and numerical studies, the nature of the destruction of beams, their deformation and the nature of cracking are determined. Experimental and numerical relationships of relative deflections on relative bending moments are obtained. A comparative analysis of the values of the bearing capacity and the relative height of the compressed zone of the beams, obtained experimentally, numerically and according to SP 63.13330.2018, was carried out. The nature of the distribution of deformations in concrete of normal section of beams at different levels of loading is determined.

Mechanical Analysis of Semi-Rigid Base Asphalt Pavement under the Influence of Groundwater with the Spectral Element Method

Over prolonged exposure to groundwater conditions, semi-rigid base asphalt pavements can undergo significant changes in their internal moisture field, resulting in substantial variations in the pavement’s stiffness and, consequently, affecting the overall load-bearing capacity and stability of the road structure. This paper employs FWD non-destructive testing equipment to assess its mechanical performance and conduct data analysis and conducts a mechanical response study of asphalt road surfaces, considering the influence of roadbed moisture levels. Using the dynamic analytical theory, the fundamental equations and stiffness matrices for a linear elastic half-space model were established, leading to the development of a computational model for the mechanical response of semi-rigid base asphalt pavements under FWD dynamic loading, with an examination of the surface deflection in relation to changes in groundwater levels. Numerical examples and engineering applications were employed to validate the proposed model. The research findings indicate: With the passage of time, surface deflection values initially increase and then decrease, exhibiting a sinusoidal variation pattern similar to that of the applied load. As the distance from the loading center increases, the moment of peak deflection continually lags behind. The average absolute relative error between the results obtained using the method proposed in this study and the traditional ABAQUS finite element method was only 0.70%. The correlation coefficient between the theoretically computed deflection curve and the measured deflection curve using the spectral element method was greater than 0.9, with an average absolute relative error of 4.92% between the theoretical peak deflection and the measured peak deflection. As the groundwater level rises, surface deflection noticeably increases, with an approximately 40% increase in deflection values at the loading center. These research findings can be utilized to analyze the dynamic deflection of semi-rigid base asphalt pavements under various groundwater conditions, providing significant practical value for assessing road structural performance and serviceability.

Design of auxiliary viewing mirror for filter centering drum in GD121-AF12 filter assembler

In order to solve the problem of observation blind area on the outer end face of the cigarette groove of the filter centering drum on the GD121—AF12 filter assembler, an auxiliary observation mirror was designed and installed on the inner wall nearby. According to the light reflection law, according to the space position the central position of the mirror , design the mirror surface support parts refer to the available screw holes on the mirror surface center and inner wall, and calculate the relative position and deflection angle of the support parts. Based on the above data, support parts are designed with Pro/E, and parts are made with 3D printer. After the improved equipment is blocked, the manual cleaning time is reduced to 3.2min/time, and the maintenance time is reduced by 67%, which effectively reduces the labor intensity of operators and improves the equipment efficiency.

Wave-like oscillations of clamped microtubules driven by collective dynein transport

Microtubules (MTs) are observed to move and buckle driven by ATP-dependent molecular motors in both mitotic and interphasic eukaryotic cells as well as in specialized structures such as flagella and cilia with a stereotypical geometry. In previous work, clamped MTs driven by a few kinesin motors were seen to buckle and occasionally flap in what was referred to as flagella-like motion. Theoretical models of active-filament dynamics and a following force have predicted that, with sufficient force and binding-unbinding, such clamped filaments should spontaneously undergo periodic buckling oscillations. However, a systematic experimental test of the theory and reconciliation to a model was lacking. Here, we have engineered a minimal system of MTs clamped at their plus ends and transported by a sheet of dynein motors that demonstrate the emergence of spontaneous traveling-wave oscillations along single filaments. The frequencies of tip oscillations are in the millihertz range and are statistically indistinguishable in the onset and recovery phases. We develop a 2D computational model of clamped MTs binding and unbinding stochastically to motors in a “gliding-assay” geometry. The simulated MTs oscillate with a frequency comparable to experiment. The model predicts the effect of MT length and motor density on qualitative transitions between distinct phases of flapping, regular oscillations, and looping. We develop an effective “order parameter” based on the relative deflection along the filament and orthogonal to it. The transitions predicted in simulations are validated by experimental data. These results demonstrate a role for geometry, MT buckling, and collective molecular motor activity in the emergence of oscillatory dynamics.

Damage Identification in Large‐Scale Bridge Girders Using Output‐Only Modal Flexibility–Based Deflections and Span‐Similar Virtual Beam Models

Damage identification (DI) methods using changes in static and modal flexibility (MF)–based deflections are effective tools to assess the damage in beam‐like structures due to the explicit relationships between deflection change and stiffness reduction caused by damage. However, current methods developed for statically determinate beams require the calculation of mathematical scalar functions which do not exist in statically indeterminate beams and limit their application mainly to single‐span bridges and cantilever structures. This paper presents an enhanced deflection‐based damage identification (DBDI) method that can be applied to both statically determinate and indeterminate beams, including multispan girder bridges. The proposed method utilises the deflections obtained either from static tests or proportional defections extracted from output‐only vibration tests. Specifically, general mathematical relationships between deflection change and relative deflection change with respect to the damage characteristics are established. From these, additional damage‐locating criteria are proposed to help distinguish undamaged spans from the damaged ones and to identify the damage location within the damaged span. Notably, a span‐similar virtual beam (SSVB) model concept is introduced to quantify the damage and make this task straightforward without the need to calculate complicated mathematical formulae. This model only requires information of the beam span length, which can be conveniently and accurately obtained from a real structure. The robustness of the method is tested through a series of case studies from a numerical two‐span beam to a benchmark real slab‐on‐girder bridge as well as a complex large‐scale box girder bridge (BGB). The results of these studies, including the minimal verification errors within five percent observed in the real bridge scenario, demonstrate that the proposed method is robust and can serve as a practical tool for structural health monitoring (SHM) of important highway bridges.

Load transfer of small-diameter GFRP and stainless steel doweled-joints in slabs-on-ground

Large diameter steel and glass fiber-reinforced polymer (GFRP) dowel bars are commonly used in rigid concrete pavements in highways for load transfer across joints to combat the concrete deterioration due to corrosion of steel dowels. Small-diameter GFRP dowel bars can be used at the expansion joints in slabs-on-ground, walkways, industrial floors and concrete-lined channels, which are not subjected to heavy traffic loads. This study investigated the performance and behavior of small-diameter GFRP dowels. GFRP dowels with three diameters (14 mm, 16 mm, and 38 mm) and stainless steel dowels (12 mm dia.) were embedded across a 25 mm-wide joint in a test slab with overall dimensions of 1500 × 750 × 200 mm3. The variables of the study were the type of dowel material (GFRP and stainless steel), the diameter of GFRP dowels, the spacing of the dowels (200 mm and 250 mm c/c), and the type of loading (monotonic and cyclic). The slabs were loaded up to the failure of the joints under a concentrated load applied at the edge of the joint. The performance of the dowel-jointed slab specimens was investigated based on the cracking and ultimate loads, modes of failure, and load-displacement response. The ability of the small-diameter dowel bars to transfer displacements across the joint was quantified using the quantitative measures of joint effectiveness (E), load transfer efficiency (LTE), and relative deflections (Δ). Failure of the specimens with 14 mm and 16 mm diameter dowels occurred predominantly due to shear failure of the dowels before the cracking of concrete. However, for the specimens with large-diameter GFRP dowels and the stainless steel dowels, failure was associated with cracking of the concrete. A smaller spacing of the GFRP dowels and a longer embedment length gave a stiffer load-displacement response. Reducing the spacing from 250 mm to 200 mm resulted in a 4.1-fold reduction in relative deflection under the AASHTO H10 design wheel load (∼35.6 kN). Increasing the dowel length had no significant effect on the load-carrying capacity of the dowel-jointed slabs. Cyclic load tests on the specimens revealed that the joint effectiveness (E) and the load transfer efficiency (LTE) of GFRP dowels were within the AASHTO and ACPA limits up to a concentrated load higher than the AASHTO HL93 dual tandem-axle wheel load (∼55.6 kN).

A Multi-Depth Deflectometer/Global Navigation Satellite System Method for Measuring Concrete Slab Track Deformation

This study introduces a Multi-Depth Deflectometer (MDD) combined with a Global Navigation Satellite System (GNSS) which was developed for measuring the deformation of railway slab track layers. We newly designed the MDD with the addition of laser sensor modules for increasing precision in which the MDD head is fixed at the top of the track slab. The MDD/GNSS system can measure the relative deflection between each track layer as well as the total deflection at the top of the track slab, which makes it possible to evade the fixed condition problem of classical MDD. The new MDD/GNSS system was installed at the transition zone between a tunnel entrance and its embankment, which experienced high settlement levels prior to repair. The system was used to monitor whether the repaired concrete track foundation with pressurized cement grouting was stabilized effectively and what track layer position was most unstable so that it had the most influence. The GNSS system was designed and built for computing net settlement at each track layer even when the MDD could not be fixed firmly at the end point, which is a major drawback of classical MDD. The results obtained from MDD and GNSS measurements indicated significant potential in aiding railway track settlement measurements.

Effects of Temperature on Axial Crushing Behavior of Circular Multi-Walled Tubes

In this work, the impact of temperature on the crushing performance of multi-walled tube (MWT) were investigated using a combined experimental, theoretical and numerical method. The MWT was fabricated using extrusion technology, and the temperature-dependent axial crushing experiment was performed on a hydraulic testing machine. The results show that the peak crushing force (PCF), the mean force (Pm) and the specific energy absorption (SEA) decreased near-linearly by 21.7%, 30.7% and 30.7% as the temperature increased from 25 °C to 250 °C, while the crushing load efficiency (CLE) was insensitive to temperature. The average forces obtained via numerical prediction, theoretical analysis and experimental testing were basically consistent. The numerical results indicate that varied temperature alters the number of dominant wavelets and the relative lateral deflections of MWT. In addition, compared with the competitive structures, the energy absorption property of MWT is excellent at high temperatures.

Ground testing of Al-polyurethane shape memory polymer sail material under pulsed light exposure

This article presents a study on design and testing of space sails using Al-polyurethane Shape memory polymer. The properties of the polymer are simulated and tested in the design phase, and the results are compared with the fabricated sail, which is considered nominal. The efficiency of the polyurethane sail is found to be approximately 86.5%. The controllability of the sail is enhanced using a heating system that uses light rays to heat the polymer at specific control spots. The relative deflection at these spots causes a deviation in solar momentum, resulting in a controlled displacement of the sail. This control system is found to be 42% more efficient than conventional vane-type deflection systems. The paper also presents the fabrication of a ground testing apparatus designed to test the sail specimen in laboratory conditions. The apparatus is capable of producing a vacuum chamber pressure up to −400 mm/Hg and includes a magnetic levitation platform with strong permanent magnets to neglect local gravitational effects. The platform provides support for fixing the solar sail frame made from carbon fiber composite material. The testing apparatus consists of a 1000-W halogen light source with intensity ranges of approximately 200,000 lux. Sail material with a reflective surface is exposed to controlled luminance under vacuum conditions to measure the deflection of the sail. Deflection values are recorded by means of a resistance type strain gauge and strain indicator arrangement. Plotting deflections with time period gives the acceleration of the sail inside the test apparatus. A coolant chamber with a ceramic base is also provided to reduce temperature effects inside the vacuum chamber. In conclusion, this study presents a promising approach for the design and testing of solar sails using shape memory polymer and a ground testing apparatus. The results of this research can contribute to the development of more efficient and versatile solar sail technology for fuel-free aerospace propulsion.

Investigation of the influence of the loading arrangement on the measured mode-I fracture resistance

This paper investigates the influence of the loading arrangement of double cantilever beam (DCB) test on the computed fracture resistance parameters of a structural adhesive. Aluminium joints were tested on three conventional loading arrangements from the BS ISO 25217:2009. We have found that the compliance of different loading arrangements can lead to significant differences in the fracture resistance computed using the cross-head displacement of the tensile-testing machine, even after considering the take-up of play and machine-compliance effects. In contrast, using the digital image correlation to measure the load-line displacement results in fracture resistance that is essentially independent of the loading arrangement. This finding was confirmed using three different data-reduction schemes, which yielded almost identical values of fracture resistance (less than 1% difference). Furthermore, direct identification of the traction-separation law at the crack tip was performed using Savitzky–Golay filter to compute the derivative of the J integral with regard to normal separation. Again, no significant influence of the loading arrangement was found since identified values of the separation at the peak traction and maximum separation are in excellent agreement. The identified maximum separation can be used as a threshold value of the relative deflection of the DCB arms to automatically determine the crack-tip position.

Research to complete software processing settlement monitoring data of constructions in Vietnam

Currently, there are many software for processing settlement monitoring data in Vietnam. However, these softwares still lack some module to calculate the relative deflection settlement (S/L) as well as the lack of modules for building settlement model over time. This article presents the content of establishing a program to calculate relative deflection settlement and building settlement model over time. The results of the article aim to improve the current settlement monitoring software in Vietnam in order to automate the analysis and evaluation of settlement monitoring results.

On the 3D fluid behavior during CBM coproduction in a multi pressure system: Insights from experimental analysis and mathematical models

To investigate the dynamic response characteristics of coalbed methane (CBM) reservoirs with multi pressure system induced by coproduction, physical simulation experiments were conducted on CBM coproduction under both conventional and constant-rate coproduction modes using a self-built experimental platform. The results showed that constant-rate coproduction can significantly extend the stable coproduction period of CBM compared to conventional coproduction, but it may have an inhibitory effect on certain reservoirs, which is negatively correlated with the initial reservoir pressure. Constant-rate coproduction can cause disturbance effects on reservoir pressure, leading to an increase in the expansion resistance of the pressure-reduction funnel during coproduction, and even the appearance of the pressure-buildup funnel of low-pressure reservoirs. A calculation principle for the 3D fluid flow parameters was developed by considering the dynamic permeability and the pressure gradient of the reservoir. The 3D fluid flow parameters were employed to quantitatively characterize the spatial and temporal evolution of fluid relative flow velocity and deflection angle in the reservoir during coproduction. Near the far end of the wellbore, the fluid flowed nearly horizontally, while near the wellbore, the fluid flowed towards or away from the wellbore center due to different levels of disturbance.

Using Short Ultra-High Performance Concrete Link Slab as an Alternative to Steel Dowel Bars in Rigid Pavements

To prevent problems from occurring at the joint region in bridge construction, link slab was introduced to hide the apparent expansion joint and retain its function. This research describes experimental tests that investigate the use of an ultra-high performance concrete (UHPC), for its high sustainability properties, as a short link slab instead of apparent expansion joints and their respective steel dowels in joint plain concrete pavement (JPCP) while maintaining the expansion joint’s proper function. Similar to dowelled joints, the proposed joint distributes load between adjoining slabs while allowing for contraction and expansion of the pavement due to temperature and moisture variations. Modified cantilever tests were conducted on JPCP slab segments with regular dowelled joints and UHPC link slab joints to investigate the load-deflection response and load transfer of both joints and make comparison. The experimental results showed that UHPC link slab specimens exhibited less deflection at the face of the joint and less relative deflection between the adjoining slabs than steel dowel bar specimens. The test outcomes also showed that joint width did not have a noticeable influence on the load-deflection behavior of the UHPC link slab specimens, but it obviously affected the dowelled joints. Also, UHPC link slab specimens showed an improvement in ultimate load capacity by 23.33% and 11% compared with dowelled joints. Furthermore, the UHPC link slab joints exhibited a better load transfer between slab segments than the dowelled joints. It was concluded that even a short link slab can be superior to standard dowelled joints