Linear Variable Displacement Transducers Research Articles

Tensile characteristics of ultra-high-performance fibre-reinforced concrete with and without longitudinal steel rebars

Ultra-high-performance fibre-reinforced concrete (UHPFRC) specimens with and without longitudinal reinforcement were experimentally tested under direct tensile loading. The variables considered were the volume fraction of fibres (1.0% and 2.0%), the type of steel fibres (straight and hooked end) and the longitudinal steel reinforcement ratio (none and 1.2%). All of the specimens were tested using a servo-controlled fatigue testing machine in displacement control mode. The changes in displacement were monitored using linear variable displacement transducers and the digital image correlation technique. The strain profiles at different loading stages were used to identify the crack evolution process. The average localised strain was found to be 0.2–0.36%, with corresponding crack widths of 0.3–0.6 mm. A uniaxial tensile stress–strain model was developed based on the test results and data from the literature. Longitudinally steel-reinforced specimens showed both stiffening and strengthening effects. Tension-stiffened specimens with 1.0% fibres failed at a higher strain due to the formation of multiple macrocracks. In the specimens with 2.0% fibres, the rebar fractured in a brittle manner due to crack localisation. It is concluded that a higher longitudinal reinforcement ratio is needed to utilise UHPFRC effectively under tension-dominant loads.

Online Real-Time Monitoring System of A Structural Steel Railway Bridge Using Wireless Smart Sensors

In the transportation network, railway bridges are crucial for the transfer of both passengers and commodities. Railway bridges require continuous monitoring to observe their performance. A structural health monitoring system is one method for assessing the viability of a railway bridge structure. The functioning of railroad bridge structures has been extensively observed using wireless technology. This research aims to implement smart wireless sensors for monitoring the structural health of the railway bridge online in real-time during operation. Many sensor kinds were installed on the railway bridge, including strain gauges, accelerometers, linear variable displacement transducers, and proximity sensors. Geometric modeling and numerical simulation were performed to find critical frame locations on the railway bridge where the instrumentation sensors would be placed. In this study, MONITA® is employed for data acquisition modules. The MONITA® system consists of a combination of hardware and software that functions to retrieve, send, store, and process data. This paper describes the result of the establishment of this method to comprehend the performance of the steel railway bridge structure in real-time via the human-machine interface display dashboard. As a result, the monitoring system can appropriately be used to assess a structural railway bridge in real-time. This study may be helpful to practicing engineers and researchers in future studies of steel railway bridge evaluation. This could be a useful reference for future studies in implementing such systems as the railway bridge early warning system technique in detecting bridge damage.

High-resolution photogrammetry to measure physical aperture of two separated rock fracture surfaces

Photogrammetry, reconstructing three-dimensional (3D) models from overlapping two-dimensional (2D) photos, finds application in rock mechanics and rock engineering to extract geometrical details of reconstructed objects, for example rock fractures. Fracture properties are important for determining the mechanical stability, permeability, strength, and shear behavior of the rock mass. Photogrammetry can be used to reconstruct detailed 3D models of two separated rock fracture surfaces to characterize fracture roughness and physical aperture, which controls the fluid flow, hydromechanical and shear behavior of the rock mass. This research aimed to determine the optimal number of scale bars required to produce high-precision 3D models of a fracture surface. A workflow has been developed to define the physical aperture of a fracture using photogrammetry. Three blocks of Kuru granite (25 cm × 25 cm × 10 cm) with an artificially induced fracture, were investigated. For scaling 3D models, 321 markers were used as ground control points (GCPs) with predefined distances on each block. When the samples were well-matched in their original positions, the entire block was photographed. Coordinate data of the GCPs were extracted from the 3D model of the blocks. Each half was surveyed separately and georeferenced by GCPs and merged into the same coordinate system. Two fracture surfaces were extracted from the 3D models and the vertical distance between the two surfaces was digitally calculated as physical aperture. Accuracy assessment of the photogrammetric reconstruction showed a 20–30 μm digital control distance accuracy when compared to known distances defined between markers. To attain this accuracy, the study found that at least 200 scale bars were required. Furthermore, photogrammetry was employed to measure changes in aperture under normal stresses. The results obtained from this approach were found to be in good agreement with those obtained using linear variable displacement transducers (LVDTs), with differences ranging from 1 μm to 8 μm.

UJI BEBAN PADA STRUKTUR BANGUNAN CAGAR BUDAYA JEMBATAN LOJI KOTA PEKALONGAN

The Loji Bridge in Pekalongan City is a cultural heritage building that was built in 1880, during the Dutch East Indies colonial period. The Loji Bridge is more than 150 years old and is still standing and is only used for bicycle and motorbike traffic. When it was built, it was an important bridge because it was a bridge on the north coast road. Until now, this has been the way of the economy. The condition of the bridge is currently unknown as to its structural feasibility. The Pekalongan city government will revitalize the bridge left over from the Dutch era so that it can be used again. If it is not possible for traffic to be used, it will be used as a place for MSME activities. So in the city of Pekalongan there are interesting places to attract visitors as culinary tourism spots and others.To determine the suitability of the bridge structure with a span of 50 meters, testing needs to be carried out. The test carried out is a load test. Why is a loading test carried out because there is no bridge building data, superstructure data or substructure/foundation data. So with a loading test you can immediately determine the amount of load the bridge can safely withstand.The loading method uses water loads, namely by creating a loading pool. The load is adjusted to the planned traffic load / live load. The equipment installed and recorded during the test is to determine and monitor the bridge settlement, either in the pillars or beams. Monitoring is carried out to maintain deflection / settlement. So that the decrease / deflection that occurs during testing is still within safe limits.The equipment used to monitor and record deflection is a Linear Variable Displacement Transducer (LVDT) which is connected to a data logger and computer. The LVDT is placed on wooden stakes / poles stuck into the river bed, so that the readings decrease relative to the river bed.Loji Bridge with a span of 50 meters consists of 4 pillars and 2 abutments. Upper structure with asphalt pavement, wooden plank floor. The abutments use river stone pairs and the pillars use 7 solid pipes with a diameter of 12 cm. Later, it is planned to replace the wooden floor with a reinforced concrete slab floor on the bridge.

Enhancing the damping effect of MRF damper using an external magnetic excitation system

The magnetic field generated by the damper’s magnetic circuit governs the yield stress value of the Magnetroholgical Fluid (MRF) damper and hence its damping effect. This paper contributes to the literature on the development of MRF dampers by introducing a new design feature to improve the damper’s performance. The presented novel feature tends to amplify the magnetic field value and concentrate its flux within the MR fluid region. The excitation sources consist of 12 coils placed in radial directions surrounding the MRF to focus the energizing magnetic effects. However, the search for efficient solutions is not only focused on generating more energy but also on minimizing its loss. Therefore, a metallic ring was placed around the coils to close the magnetic circuit, guide the flux lines, and avoid any energy dispersion to the surrounding air. As a proof of concept, two materials were tested for the surrounding ring: plastic acrylonitrile butadiene styrene (ABS) and mild steel. The performance of both solutions was assessed experimentally with a Gaussmeter and numerically by using a model developed via COMSOL Multiphysics. Both techniques confirmed the efficiency of the solution based on a steel ring in preventing the flux dispersion into the surrounding air. In addition, an increase of the excitation current from 0 to 5A was found to elevate the magnetic field by 35%, compared with the ABS ring. In the second step, a test rig was designed and built to investigate the damping efficiency of the MRF experimentally. The testing apparatus consisted of a sliding-bearing mechanism connected to a variable speed motor. The damping effect was assessed based on the force and displacement data provided by a linear variable displacement transducer (LVDT) and a force cell. Damping forces were observed at a constant frequency of 0.36 Hz (22 rpm) when the testing system and the attached damper were functioning smoothly away from its resonant frequency. Moreover, the magnetic field excitation current was elevated from 0 A to 5 A with a 1 A step. Again, the metallic ring was found to produce a 112% greater damping coefficient than the case of the plastic ring when the excitation current reached 5A.

Synthesis and Characterization of Dental Nanocomposite Resins Reinforced with Dual Organomodified Silica/Clay Nanofiller Systems.

Quaternary ammonium (QA) compounds have been widely studied as potential disinfectants in dental restorative materials. The present work investigates whether the gradual displacement of nanosilica by QA-clay nanoparticles may have an impact on the physicochemical and mechanical properties of dental nanocomposite resins. For this purpose, Bis-GMA/TEGDMA-based composite resins were initially synthesized by incorporating 3-(trimethoxysilyl)propyl methacrylate (γ-MPS)-modified nanosilica/QA-clay nanoparticles at 60/0, 55/5, 50/10, 40/20, and 30/30 wt% filler loadings. Their structural characterization was performed by means of scanning electron microscopy (SEM) and X-ray diffraction analysis (XRD). The degree of double bond conversion (DC) over time and the polymerization shrinkage were determined with Fourier transform infrared spectroscopy (FTIR) and a linear variable displacement transducer (LVDT), respectively. Mechanical properties as well as water sorption and solubility parameters were also evaluated after storage of nanocomposites in water for 7 days at 37 °C. Spectral data revealed intercalated clay configurations along with areas characterized by silica-clay clusters for clay loadings up to 30 wt%. Furthermore, the insertion of 10 wt% QA-clay enhanced the auto-acceleration effect also sustaining the ultimate (DC), reduced the setting contraction and solubility, and, finally, yielded flexural modulus and strength very close to those of the control nanocomposite resin. The acquired results could herald the advanced design of dental restorative materials appropriate for contemporary clinical applications.

Full Scale Bend Test of a Multi Stage Aerospace Vehicle

Evaluation of structural integrity of a missile involves sectional and full scale tests. Tests are carried out for transportation, articulation and aerodynamic loads. Uniqueness of carrying full scale bend test of a multi stage aerospace vehicle lies in the qualification of not only structural integrity of different sections but also the joints. Empty missile structure forms the testing frame. A bending moment envelope is simulated using a combination of upward and downward loads. Design and realization of open configuration test rig frames in order to simulate the necessary boundary conditions was executed. The output measurements for the test are strains, deflections and joint rotation constants. Linear Variable Displacement Transducers (LVDTs) measures the deflections normal to the missile axis and help in mapping of the deflection pattern along the length of the missile. CODs (Crack Opening Devices), developed in-house, are used to measure the joint openings during the bend test. The measured Joint Rotation Constants (JRCs) are in-turn used as input to refine the Finite Element (FE) model, thereby improvising the accuracy of the predicted results from the FE model.

Bond-slip response of corroded SD bars with recycled coarse aggregate concrete

Recycled aggregate concrete (RAC) has been the subject of numerous research to ensure the efficient use of aggregates made from recycling old concrete by examining various parameters in fresh and hardened phases. The present study investigates the bond-slip response of Recycled coarse aggregate concrete (RCAC) with Super Ductile (SD) reinforcing steel exposed to corrosion with varying degrees. SD rebar category is relatively new compared to the hot-rolled and TMT classes of reinforcing steel. SD has a superior bonding performance with concrete owing to the distinctive rib patterns. RILEM-specified cylindrical pull-out specimens were fabricated with RCA concrete with replacement ratios of (0%, 25%, 50%, 75%, and 100%) and centrally embedded SD bars. Pull-out specimens were immersed in NaCl solution before exposure to impressed current corrosion to achieve desired levels of corrosion. The specimens were tested for failure in a displacement-controlled Pull-out testing universal testing machine (UTM). A set of linear variable displacement transducers (LVDT) recorded the slip of the rebar at both the loaded and unloaded ends. The bond-slip response was used to characterize the overall behavior of the bond mechanism. Predictive models have been suggested for the bond strength of RCAC following corrosion. The results indicate that the bond strength of RCAC is almost similar to that of the natural aggregate concrete (NAC) exposed. The results indicated that both the bond slip and bond degradation hold good and agree with previous models. The findings can help anticipate the performance of structural elements made of recycled coarse aggregate concrete (RCAC) exposed to aggressive environments.

Flexural performance of concrete composite metal decking with different base-metal-thickness new smart system

Industrial Revolution 4.0 has led to the age of automation and industrialized building systems. Composite slabs gain its popularity in the modern construction industry due to its speed of construction and cost saving features with lightweight structure. However, from time to time the manufacturer will introduce new corrugated roll forming cold formed steel metal decking systems, which cause the end user to ponder if the product is up to desired performances. The aim of this research is to study the structural performance of SMARTDEK composite slab composed of 0.75 mm and 1.0 mm thickness compared to the conventional reinforced concrete slab under flexural strength, deflection, and failure mode. Concrete slab with thickness of 130 mm was constructed to uncover the ultimate load capacity of the slabs. The novelty of this research is the discovery of longitudinal shear resistance constant through derived equations and the new SMARTDEK profiled composite slab performs better than the conventional slab. Four-point flexural tests were conducted according to ASTM C293 standards to determine the performance of the slabs, and three linear variable displacement transducers (LVDTs) were used to determine the deflection of the slabs. Load-Deflection graphs were plotted for the specimens to determine the yielding point and ultimate point of the slabs. The composite slab with 1.0 mm Base-Metal-Thickness (BMT) had the highest ultimate strength at 75 kN, followed by the composite slab with 0.75 mm BMT at 65 kN, and finally the conventional slab at 39 kN. The failure mode of the conventional slab was pure flexural; while the composite slab first failed in flexural, followed by longitudinal slip failure due to flexural and flexural-shear cracks, which disabled the composite action between the concrete slab and metal decking. The finding showed that the increasing thickness of the metal decking improves the slab strength which results in higher ultimate strength and reduces the overall deflection of the slab. Moreover, the breakthrough of this research is that increasing the overall thickness of the slabs increases the performance in loading’s capacity which could result in higher ultimate strength.

Interfragmentary strain measurement post-fixation to guide intraoperative decision making: a narrative review.

Interfragmentary strain influences whether a fracture will undergo direct and indirect fracture healing. Orthopedic trauma surgeons modulate strain and create optimal biomechanical environments for specific fracture patterns using fixation constructs. However, objective intraoperative interfragmentary strain measurement does not currently inform fixation strategy in common practice. This review identifies potential methods and technologies to enable intraoperative strain measurement for guiding optimal fracture fixation strategies. PubMed, Scopus, and Web of Science were methodologically queried for manuscripts containing terms related to "bone fracture," "strain," "measurement," and "intraoperative." Manuscripts were systematically screened for relevance and adjudicated by three reviewers. Relevant articles describing methods to measure interfragmentary strain intraoperatively were summarized. After removing duplicates, 1404 records were screened initially. There were 49 manuscripts meeting criteria for in-depth review. Of these, four reports were included in this study that described methods applicable to measuring interfragmentary strain intraoperatively. Two of these reports described a method using instrumented staples, one described optical tracking of Kirschner wires, and one described using a digital linear variable displacement transducer with a custom external fixator. The four reports identified by this review describe potential methods to quantify interfragmentary strain after fixation. However, further studies are needed to confirm the precision and accuracy of these measurements across a range of fractures and fixation methods. Additionally, described methods require the insertion and likely removal of additional implants into the bone. Ideally, innovations that measure interfragmentary strain intraoperatively would provide dynamic biomechanical feedback for the surgeon to proactively modulate construct stability.

Experimental study on the bond performance of deformed steel bar in ultrahigh performance concrete

Ultrahigh performance concrete (UHPC) has emerged as a relatively new material showing excellent ductility compared to normal concrete, and it has the potential to be used in combination with steel bars in several engineering application scenarios. The interfacial bond performance is the key to determining the effectiveness of force transfer between different materials, which is required to achieve a refined analysis of member behaviour. In this study, central unidirectional pull-out tests of 54 prismatic specimens with deformed steel bars embedded in UHPC were carried out without lateral constraints. The sizes of the specimens included two types: design size and standard size (200 mm × 200 mm × 200 mm). The design size was related to different combinations between anchorage lengths (2, 3, and 4 times the diameter) and concrete covers (2, 3, and 4 times the diameter) of steel bars, which were also the primary variables of this test. Eighteen standard specimens were used to explore the strain change law along the anchorage length of the steel bar. The specimen was loaded according to the displacement control of 1 mm/min on the static tensile loading system, and a linear variable displacement transducer (LVDT) was arranged on both sides of the loading end and the free end of the specimen to collect data continuously. The strain distribution, anchorage lengths, concrete covers, critical anchorage length, maximum bond stress and bond stressslip model of deformed steel bars in UHPC were all thoroughly investigated. Generally, the results revealed that when the anchorage length exceeded two times the diameter of the steel bar, the maximum strain appeared at approximately 1.5 times the diameter away from the loading end. The maximum bond stress decreased with increasing anchorage length, and the maximum reduction was approximately 54.42%, but this law did not apply to the concrete cover. The maximum bond stress increased with increasing concrete cover, and the gain in peak load was approximately 18.23%. However, the excessive concrete cover did not bring a noticeable gain effect. In addition, compared with several existing bond stressslip models, the improved model proposed in this study was in good agreement with the experimental results, and the determination coefficient of related parameters was basically above 0.95.

A new experimental device developed to study the creeping behavior of a rock joint under shear stress

In the context of nuclear waste management project Cigeo, the behavior of the fractured Callovo Oxfordian claystone (COx) is studied for its time dependent effect on the long term convergences of the drifts. We present an experimental setup designed to investigate the viscous behavior of a fracture. While few experimental setup already exist with the purpose of studying the time dependent deformation of a rock joint, all of them measure the displacement in the direction of the sheared discontinuities in one point of the sample with devices such as a linear variable displacement transducers (lvdt). The information provided by this sensor comes to measuring the average displacement of the fracture slip. Depending on the configuration of the experimental device, the lvdt sometimes also measures the deformation of the rock medium which cannot always be considered as a rigid body. Which is why we propose in this paper to set a camera up in order to use Digital Image Correlation to get an information of the slip along the fracture.

SHEAR TRANSFER BEHAVIOR OF FIBROUS CONCRETE

Fibrous concrete's shear strength behavior is important in structural design. Brackets, corbels, and ledger beams are examples of concrete members that might collapse in shear. Such a failure might be brittle and sudden. Fibers improve concrete's behavior by increasing residual shear transfer and reducing crack development and extension. In an experimental study, nine push-off specimens were divided into three groups and examined as part of the experiment. Conventional concrete, conventional concrete with 1% glass fiber, and conventional concrete with 1% steel fiber were the groups. There were three push-off specimens with various shear reinforcement ratios in each of the groups that were examined (0.0, 0.45, and 0.68%). The specimens utilized had dimensions of 500mm x 250mm x 125mm. The vertical slip and horizontal separation at the shear plane were measured using two-stroke linear variable displacement transducers (LVDT). The effect of fiber type and the ratio of transverse reinforcement across the shear plane were the parameters evaluated. The presence of fibers enhances final shear strength, which is more obvious in specimens without stirrups in the shear plane. Where the addition of 1% of glass fiber to normal strength concrete increased ultimate shear strength by 32.26%, 12.38%, and 12.5%, while adding 1% of steel fiber to normal strength concrete increased ultimate shear strength by up to 53.22%, 19%, and 25%, respectively, for the specimens without stirrups, two stirrups, and three stirrups. The fibrous specimens were stiffer and ductile failure was seen. Steel fibers improved overall concrete shear behavior better than glass fibers.

Efficacy and Damage Diagnosis of Reinforced Concrete Columns and Joints Strengthened with FRP Ropes Using Piezoelectric Transducers.

Recent research has indicated that the implantation of a network of piezoelectric transducer patches in element regions of potential damage development, such as the beam-column joint (BCJ) area, substantially increases the efficacy and accuracy of the structural health monitoring (SHM) methods to identify damage level, providing a reliable diagnosis. The use of piezoelectric lead zirconate titanate (PZT) transducers for the examination of the efficiency of an innovative strengthening technique of reinforced concrete (RC) columns and BCJs is presented and commented on. Two real-scale RC BCJ subassemblages were constructed for this investigation. The columns and the joint panel of the second subassemblage were externally strengthened with carbon fiber-reinforced polymer (C-FRP) ropes. To examine the efficiency of this strengthening technique we used the following transducers: (a) PZT sensors on the ropes and the concrete; (b) tSring linear variable displacement transducers (SLVDTs), diagonally installed on the BCJ, to measure the shear deformations of the BCJ panel; (c) Strain gauges on the internal steel bars. From the experimental results, it became apparent that the PZT transducers successfully diagnosed the loading step at which the primary damage occurred in the first BCJ subassemblage and the damage state of the strengthened BCJ during the loading procedure. Further, data acquired from the diagonal SLVDTs and the strain gauges provided insight into the damage state of the two tested specimens at each step of the loading procedure and confirmed the diagnosis provided by the PZT transducers. Furthermore, data acquired by the PZT transducers, SLVDTs and strain gauges proved the effectiveness of the applied strengthening technique with C-FRP ropes externally mounted on the column and the conjunction area of the examined BCJ subassemblages.

Simultaneous characterization of preform expansion and permeability in vacuum assisted resin infusion

AbstractVacuum assisted resin infusion (VARI) is a composite manufacturing process, in which a fibrous reinforcement is laid out in a mold, and then sealed under a vacuum bag. The preform is compressed under vacuum and a liquid polymer resin is infused into the mold cavity. A characterization of compressibility and permeability is required to get accurate predictions of infusion times and thickness of final parts. A new experimental methodology is developed to simultaneously characterize the preform expansion and permeability of fibrous reinforcements during infusion. It is implemented in a one‐dimensional rectangular workbench by impregnating the preform with silicone oil. Pressure sensors measure the liquid pressure, and the reinforcement thickness is acquired by linear variable displacement transducers (LVDTs). The flow rate is also recorded with a scale. The expansion of the wetted reinforcement and permeability can be modeled by power laws as a function of pressure and fiber volume content, respectively. For isotropic preforms, a single experiment provides all the information needed to simulate the flow and predict the infusion time, the thickness and pressure. To validate this new characterization approach, the results of two infusions are successfully compared with numerical simulations.

Textile Reinforced Mortars (TRM) tensile behavior after high temperature exposure

Although one of the main advantages of Textile Reinforced Mortars (TRM) is their non-combustible character, their behavior against fire or high temperatures has not been sufficiently studied at present. This work analyzes the behavior of different commercial systems containing inorganic mortars and fabric reinforcements based on glass, carbon and basalt fibers, subjected to different temperature levels. To characterize the mechanical response of the different systems, non-destructive tests have been carried out to determine the dynamic modulus of elasticity of the different materials, and subsequent destructive tests to determine their strength and stress-strain relationship. For this purpose, the TRM coupons have been subjected to uniaxial tensile tests and the deformations have been monitored using LVDT (Linear Variable Displacement Transducer) sensors and DIC (Digital Image Correlation), in order to evaluate cracking patterns and failure modes. The results show, in general terms, that the mechanical capacity of these materials is seriously compromised at temperatures in the order of 400 to 600 °C, which can easily be reached during a fire inside a building. Therefore, it can be concluded that although these systems are erroneously perceived as fire resistant in many cases, they may require additional protection depending on the specific use for which they are intended.

Macro-strain based deflection and neutral axis position monitoring of reinforced concrete beams during corrosion

This article proposes a new technique of monitoring neutral axis positions and deflection of Reinforced Concrete (RC) beam during corrosion of steel reinforcement using macro-strain measurements of distributed long-gauge sensors. A different group of distributed long-gauge Packaged Carbon Fiber Line (PCFL) sensors with self-compensation and effective packaging system is installed on the compression and tension fibers of the concrete surface and steel reinforcements of RC beam to verify the proposed method experimentally. An accelerated corrosion method utilizing a salt solution and the constant current was used to achieve the required corrosion levels. The estimated deflection measured by the developed method is compared with the results using Linear Variable Displacement Transducer (LVDTs). It has been demonstrated that long-gauge PCFL sensors could provide the same accuracy. The distributed measured strains were utilized to evaluate the deterioration of the structure’s health with the advance of corrosion. Based on corrosion monitoring experimental results, it can be confirmed that using distributed PCFL sensors mounted on steel reinforcements or concrete surface, the locations and progress of the damage with corrosion time can be detected effectively. The maximum error in the estimated deflection from PCFL sensors mounted on the concrete surface compared to the LVDTs before the onset and after 24 h of accelerated corrosion was 0.5% and 2.5%, respectively.

Procena položaja bez senzora i identifikacija vremena prelaza za kalem elektromagnetnog ventila velike brzine za uključivanje/ isključivanje

In this paper, a sensorless method of detecting the spool position of a high-speed on/off solenoid valve is presented. The method depends on analyzing the time-current curve of the solenoid coil passing current and measuring the maximum stroke of the valve spool, such that the dynamic behavior of the valve is estimated and the spool displacement curve is plotted. A mathematical model of the solenoid valve is developed and the effect of the hydraulic force on the valve spool is studied. Experimental results show that the proposed method error is less than 7% when compared to valve spool displacement measured by the commonly used linear variable displacement transducer.

Structural and physical evaluation of a reinforced beam using strain gauges

In this research project,the deformations in the longitudinal and transverse reinforcing steel of a reinforced concrete beam with 2ϕ½” were estimated.Additionally,the displacements in thecenter of thespanweremeasuredtogether with theloads, which generatedthecrackingof the beam of dimensions180 mm×240 mm×3100 mm.Displacement were performed using a linear variable displacement transducer, and strain gauges were used to measure deformations. Finally, the applied load’s measurements were obtained with a load cell Pinzuar/Model-100/20T equipment.The physical-mechanical properties of the concreteused were determined through compressive strength tests at 28 days and modulus of elasticity.For this purpose, a load-bearing frame was used to support the beam at three points for load application.The data was collected directly on the Quantum/X2 equipment and analyzed with the help of the Catman/AP software.The maximum deformations found in the bending test at three point since there inforced concrete beam we are not greater than 8483µm/mm,presenting a failure in the center of the beam due to the creep of the tensile steel for a maximum load of 3115 Kg.Finally,the physical behavior of there inforced concrete beam with applying aload allows evaluating and optimizing this kind of systems.

Smart monitoring of a full-scale composite hydrofoil manufactured using automated fibre placement under high cycle fatigue

Fibre reinforced composites materials offer a pathway to produce passive shape adaptive smart marine propellers, which have improved performance characteristics over traditional metallic alloys. Automated fibre placement (AFP) technology can provide a leap forward in cyber-physical automated manufacturing, which is essential for the implementation and operation of smart factories in the marine propeller industry towards Industry 4.0 readiness. In this paper, a comprehensive structural health monitoring routine was performed on an AFP full-scale composite hydrofoil to gain confidence in its dynamic and structural performances through a number of active and passive sensors. The hydrofoil was subjected to constant amplitude flexural fatigue loading in a purpose-built test rig for 105 cycles. The hydrofoil was embedded with distributed optical fibre sensors, traditional electrical strain gauges and linear variable displacement transducers. Both microelectromechanical system and piezoelectric accelerometers were used to conduct experimental modal analyses to observe changes in the modal response of the hydrofoil at regular intervals throughout the fatigue program. The hydrofoils modal response, as well as the stiffness measured using both displacements and strains, remained unchanged over the fatigue loading regime demonstrating the structural integrity of the hydrofoil. The optical fibre sensors endured the fatigue test cycles showing their robustness under fatigue loads. Furthermore, the sensing systems demonstrated the potential of being utilised as a useful maintenance tool combining their adaptability with automated manufacturing during manufacturing through integration within the hydrofoil, a structural test framework for performance measurement, data acquisition and analytics for visualisation, and the prospect of decision making for maintenance requirement during any onset in structural performance.