Severe Bending Research Articles

Seismic performance and calculation method for plastic hinge length of RC pier reinforced with UHPC

Piers are highly vulnerable load-bearing components, and their seismic performance determines the integral seismic resistance of bridges to a certain degree. They play crucial roles in evacuation during earthquakes and post-earthquake rescue. The manner in which piers meet the seismic performance requirements after reinforcement has become a popular research topic. In this study, ultra-high-performance concrete (UHPC) and HTRB600E high-tensile reinforcements were used to expand the cross section of a cast-in-place square pier with severe bending damage. The earthquake-resistant behaviour indicators of the pier were compared and analysed by conducting pseudo-static tests on a reinforced concrete pier before and after reinforcement. These indicators included the hysteretic curve, skeleton curve, energy dissipation curve, rigidity degradation, residual displacement, and pier body curvature. Based on the results of the seismic reinforcement quasi-static tests, a finite element model (FEM) of the bridge pier was constructed using the ABAQUS software, and the accuracy of the FEM was averaged. The impact of the reinforcement layer height, thickness, longitudinal strength and axial compression ratio on the equivalent plastic-hinge length of the reinforced pier was analysed, and the formula for the equivalent plastic-hinge length of the reinforced pier was obtained based on multiple linear regression fitting. The analysis results demonstrated that the broadened section method, utilising UHPC and high-tensile reinforcement, significantly enhanced the flexural capacity, energy dissipation, and first rigidity of the bridge pier. The earthquake-resistant behaviour of pier was effectively restored and improved, and the seismic reinforcement effect was significant. The equivalent plastic hinge length of the pier after reinforcement is proportional to the height of the reinforcement layer, the thickness of the reinforcement layer, the strength of the longitudinal reinforcement, and inversely proportional to the axial compression ratio.

Dynamics Modeling and Motion Evaluation of a Near-Ground Tethered Balloon Cable System under Severe Wind Environments

Weather survival poses a significant challenge for the utilization of tethered balloons. The dynamic modeling of tethered balloon systems presents challenges due to the flexible nature of the cables and the intricate nature of gust forces. The present study introduces a new approach for modeling near-ground tethered balloon systems, which enables the analysis of their dynamic responses and performance evaluation under complex boundary conditions. First, finite cylindrical rigid bodies that are joined together by bushing forces to describe the dynamics of the tethered cable. The properties of the flexible cables under severe bending and translation can be illustrated by the dynamics model. Second, a three-dimensional dynamics model based on the multibody dynamics theory is created to deal with the interaction of the tethered balloon system and flexible cables. The dynamic responses of the tethered balloon system under challenging operating conditions are investigated, focusing on the number of cable segments and the place and direction of gust wind impacts. This model allows for precise assessment and optimization of the system’s overall performance to improve weather resistance. The results show that compared to computational fluid dynamics (CFDs) methods, the multibody system dynamics-based balloon model improved the solution time by 80%, with a pitch angle deviation of only 0.0016°. Moreover, the bushing model effectively reduced cable force and enabled accurate reflection of the system’s motion characteristics.

Vitamin D deficiency, pregnancy, and childbirth in early medieval Milan

This paper explores the burden of osteomalacia on pregnancy and childbirth through two cases from early medieval urban Milan. Two skeletons of female individuals with skeletal deformities and associated with 25–36 gestational weeks fetuses, excavated from the Ad Martyres and San Vittore al Corpo urban cemeteries and dated to the Early Middle Ages, were examined. Paleopathological and historical analyses were performed in a biocultural approach to investigate the impact of clinical complications and skeletal deformities on their daily life, the course of their pregnancy, and childbirth. The women showed severe skeletal deformities attributable to osteomalacia including scoliosis, reduced rib-neck angle, coxavara, severe bending of the pelvic bones, protrusio acetabuli, and narrowed pelvic outlet. The condition and its biomechanical complications impacted the health of both mothers and fetuses, the quality of life of the women (i.e., gait alteration, difficult and limited mobility, compression of internal organs), as well as pregnancy outcomes. It is possible that both the mothers and fetuses died due to childbirth complications. Bioarchaeological cases of osteomalacia, pregnancy, and death during childbirth are excessively rare. This paper also provides insight into how maternal experiences and biocultural environments in early medieval Milan impacted childbirth outcome. The study of the Ad Martyres and San Vittore al Corpo necropolises is still ongoing and could provide further insight. Isotopic and paleogenomic analyses may shed more light into the factors that led to vitamin D deficiency in these women.

Flexo-Phototronic Boosted Self-Powered Ultraviolet Detection in ZnAl:Layered Double Hydroxide Nanosheets/NiO Heterostructure.

Developing self-powered and flexible optoelectronic sensors with high responsivity and speed is crucial for modern applications, motivating continuous efforts to enhance their performance. Flexo-phototronics is a less-explored but promising technique to elevate the performance of optoelectronics. Therefore, this work addresses the potential of utilizing the flexo-phototronic effect to enhance the performance of a flexible and self-powered ultraviolet photodetector (UV PD) based on ZnAl:LDH (layered double hydroxides) nanosheets (Ns)/NiO heterostructure. The vertically oriented ZnAl:LDH Ns are synthesized via a simple method involving the immersion of a sputtered 10% Al-doped ZnO thin film in deionized water at room ambient conditions. The fabricated PD exhibits an impressive response to 365 nm UV light, with high sensitivity in the order of 103. The device's photocurrent and responsivity are significantly enhanced by the flexo-phototronic effect, attributed to the flexoelectric properties of ZnAl:LDH Ns. Specifically, applying an inhomogeneous tensile strain of 2% boosted the device responsivity by 57.1% and improved its operational speed. Furthermore, a working model revealing the altered energy-band structure is demonstrated to elucidate the flexo-phototronic-induced boost in the photoresponse. The PD also demonstrated a sustainable performance under severe bending cycles, underlining the good flexibility of the device. The results presented in this study demonstrate a self-powered and flexible UV PD and provide a viable approach to augment the performance of optoelectronics through the flexo-phototronic effect.

Experimental investigation of dynamic characteristics of leaching tubing for solution mining of salt cavern carbon and energy storage

Salt caverns are extensively utilized for storing various substances such as fossil energy, hydrogen, compressed air, nuclear waste, and industrial solid waste. In China, when the salt cavern is leached through single-well water solution mining with oil as a cushion, engineering challenges arise with the leaching tubing, leading to issues like damage and instability. These problems significantly hinder the progress of cavern construction and the control of cavern shape. The primary cause of this is the flow-induced vibration instability of leaching tubing within a confined space, which results in severe bending or damage to the tubing. This study presents a model experimental investigation on the dynamic characteristics of leaching tubing using a self-developed liquid-solid coupling physical model experiment apparatus. The experiment utilizes a silicone-rubber pipe (SRP) and a polycarbonate pipe (PCP) to examine the effects of various factors on the dynamic stability of cantilevered pipes conveying fluid. These factors include external space constraint, flexural rigidity, medium outside the pipe, overhanging length, and end conditions. The experiments reveal four dynamic response phenomena: water hammer, static buckling, chaotic motion, and flutter instability. The study further demonstrates that the length of the external space constraint has a direct impact on the flutter critical flow velocity of the cantilevered pipe conveying fluid. Additionally, the flutter critical flow velocity is influenced by the end conditions and different external media.

Synergistically achieving high strength and impact toughness in Ti–6Al–4V-0.5Mo-0.5Zr alloy pipe with bimodal microstructure

To achieve high strength and high impact toughness, three kinds of bimodal microstructure of Ti–6Al–4V-0.5Mo-0.5Zr alloy pipe were tailored through solution treatment at the α+β phase region (860 °C, 890 °C, and 920 °C) and followed by aging at 500 °C. The bimodal microstructure consists of the primary α (αp) and β-transformed domain (βt), in which the secondary α phase (αs) precipitated in the β matrix, with different volume fraction. With the increase in solution temperature, the grain size of αp remained unchanged while the volume fraction decreased. At the same time, the volume fraction of βt and the width of αs phase increased. Furthermore, the content of low-angle grain boundaries inside the αp phase decreased. Subsequent aging resulted in finer precipitation of αs within the βt domain. Solution treatment at 890 °C and ageing at 500 °C (denoted as the STA890 sample) achieved an excellent combination of yield strength 903 MPa, tensile strength 1023 MPa, elongation 12.9%, and impact energy 31 J. With the increase of αs width, the strength of the alloy decreased, and the ductility increased slightly. Higher impact energy originated from {10 1‾ 2} tension twins activated in the STA890 sample during the impact loading process, αp and βt underwent severe bending and plastic deformation. The present study provides a feasible industrial heat treatment strategy for improving impact energy with high strength of the α+β titanium alloy pipe used for oil drilling.

Bending fatigue performance of high-strength seven-wire monostrand

Large-amplitude cable vibrations are remarkably common in cable-stayed bridges subjected to wind and mechanical loading due to low inherent damping of these structures. Although the high slenderness ratio of cables means that bending moments are not normally significant over their free length, local effects near the cable anchorage induce non-negligible bending stress variation under dynamic loading, which could lead to fatigue failure of stay cables. In modern parallel strand stay cables, the fatigue performance depends on the fatigue properties of the individual seven-wire monostrands which together make up the cable. We introduce a new bending fatigue testing device for seven-wire monostrand which can control the fatigue loading in the axial and transverse directions of the cable independently. The fatigue endurance of monostrand with guide deviators is significantly longer than without guide deviators present, especially for smaller bending fatigue amplitudes. We found that bending fatigue life of monostrand is also reduced by increased constant or dynamic axial stress, but over-tensioning of the monostrand (e.g. during construction) had no consistently adverse effect on fatigue life. For monostrand loaded in severe bending, fatigue occurs due to the bending stress variation caused by the combination of bending moments and axial forces at the extreme edges of the monostrand cross-section, rather than due to relative movement and fretting between adjacent wires within the monostrand.

Low-Temperature, Universal Synthetic Route for Mesoporous Metal Oxides by Exploiting Synergistic Effect of Thermal Activation and Plasma.

Mesoporous metal oxides exhibit excellent physicochemical properties and are widely used in various fields, including energy storage/conversion, catalysis, and sensors. Although several soft-template approaches are reported, high-temperature calcination for both metal oxide formation and template removal is necessary, which limits direct synthesis on a plastic substrate for flexible devices. Here, a universal synthetic approach that combines thermal activation and oxygen plasma to synthesize diverse mesoporous metal oxides (V2O5, V6O13, TiO2, Nb2O5, WO3, and MoO3) at low temperatures (150-200°C), which can be applicable to a flexible polymeric substrate is introduced. As a demonstration, a flexible micro-supercapacitor is fabricated by directly synthesizing mesoporous V2O5 on an indium-tin oxide-coated colorless polyimide film. The energy storage performance is well maintained under severe bending conditions.

Breaking through the bending limit of Al-alloy tubes by cryogenic effect controlled mechanical properties and friction behaviours

Aluminium alloy (Al-alloy) tubes, especially large-diameter thin-walled tubes with a tough bending radius, have been widely utilised in different industrial clusters owing to their high strength-to-weight ratio and good corrosion resistance. However, achieving such extreme specifications is challenging because severe and nonuniform bending deformation may cause tension and compression instabilities, such as overthinning, cracking, and wrinkling. Considering possible improvements in mechanical properties and friction behaviours of Al-alloy at cryogenic temperature (CT), the cryogenic bending potential of the 6061-O tubes with an extreme ratio of D/t of 89 (diameter/wall thickness) was explored at different deformation temperatures, including room temperature (RT) 20 °C, −60 °C, −120 °C, and −180 °C. First, the cryogenic mechanical properties and friction behaviour of the tubes were characterised. It was found that the overall mechanical properties of the Al-alloy tube were improved because of sub-grain formation and a more uniform distribution of dislocations at CT. The coefficient of friction between the tube and tooling exhibited a varying degree of reduction owing to the sensitivity of the tubes and the lubricant to CT. Subsequently, an innovative experimental platform for cryogenic bending was designed, and a finite element model of cryogenic bending was established. Third, cryogenic tube bendability and mechanism were explored. It was found that 6061-O tube formability can be effectively improved by cryogenic bending; however, there is no monotonic relationship between the bendability improvement and temperature decrease. The temperature to obtain the best bendability is −60 °C, at which the average wrinkle height is decreased by 81.4 %, and the average wall thickness reduction rate is reduced by 23.8 %. The bending limit represented by the bending radius is reduced from a 3.0D bending radius at RT to 1.0D at −60 °C, which is realised by the different or even opposite effects of the mechanical properties of tubes and the friction coefficient between the multiple contact interfaces on wall thinning and wrinkling.

CdSe-nanoparticles-regulated synthesis of ZnCo-MOFs derived conductive porous carbon nanoflakes on carbon cloth for flexible sodium-ion supercapacitors

Porous carbon derived from metal-organic frameworks (MOFs) represents a novel class of carbonaceous materials with unique structural characteristics, conductivity, and chemical stability, rendering them suitable for electrodes in supercapacitors. Herein, a three-dimensional structure of conductive porous carbon nanoflakes (CPCN) is synthesized based on MOFs composed of organic ligands containing zinc and cobalt. Nanoscale CdSe particles serving as energy-storage materials are incorporated into CPCN (CdSe/CPCN@CC) to form the flexible electrode for sodium-ion supercapacitors. The electrochemical properties of CdSe/CC, CdSe/ZnCo-MOF@CC, Cd/CPCN@CC, and CdSe/CPCN@CC are studied in 1 M Na2SO4. The CdSe/CPCN@CC electrode shows an impressive specific capacitance of 893.52 F g-1 at a current density of 0.125 mA cm-2 and excellent cycling stability with 80.68% retention after 10,000 cycles in 1.0 M Na2SO4. The asymmetric supercapacitor constructed with CdSe/CPCN@CC and 1 M NaPF6 electrolyte shows a capacitance of 97.8 F g-1, an energy density of 139.10 Wh kg-1, and a power density of 589.82 W kg-1 at a current density of 1 mA cm-2. In addition, the capacitance retention is 88.45% after 10,000 cycles. The electrochemical properties of CdSe/CPCN@CC are improved due to the incorporation of more active materials as well as the synergistic effects of the CdSe nanoparticles and CPCN. Density-functional theory (DFT) calculations reveal a sodium ion adsorption energy of -1.0692 eV and large DOS near the Fermi level. More importantly, in spite of severe mechanical bending, the device continues to power an LED array boding well for flexible and wearable applications.

Inferring mechanical properties of the SARS-CoV-2 virus particle with nano-indentation tests and numerical simulations

The pandemic caused by the SARS-CoV-2 virus has claimed more than 6.5 million lives worldwide. This global challenge has led to accelerated development of highly effective vaccines tied to their ability to elicit a sustained immune response. While numerous studies have focused primarily on the spike (S) protein, less is known about the interior of the virus. Here we propose a methodology that combines several experimental and simulation techniques to elucidate the internal structure and mechanical properties of the SARS-CoV-2 virus. The mechanical response of the virus was analyzed by nanoindentation tests using a novel flat indenter and evaluated in comparison to a conventional sharp tip indentation. The elastic properties of the viral membrane were estimated by analytical solutions, molecular dynamics (MD) simulations on a membrane patch and by a 3D Finite Element (FE)-beam model of the virion's spike protein and membrane molecular structure. The FE-based inverse engineering approach provided a reasonable reproduction of the mechanical response of the virus from the sharp tip indentation and was successfully verified against the flat tip indentation results. The elastic modulus of the viral membrane was estimated in the range of 7–20 MPa. MD simulations showed that the presence of proteins significantly reduces the fracture strength of the membrane patch. However, FE simulations revealed an overall high fracture strength of the virus, with a mechanical behavior similar to the highly ductile behavior of engineering metallic materials. The failure mechanics of the membrane during sharp tip indentation includes progressive damage combined with localized collapse of the membrane due to severe bending. Furthermore, the results support the hypothesis of a close association of the long membrane proteins (M) with membrane-bound hexagonally packed ribonucleoproteins (RNPs). Beyond improved understanding of coronavirus structure, the present findings offer a knowledge base for the development of novel prevention and treatment methods that are independent of the immune system.

A Finite Element Analysis of Cold Deep Drawing of Al Alloy Considering Friction Condition and Corner Design of Plunger

This study presents an innovative methodology that integrates experimental investigations with finite element simulations to ascertain the validity and reliability of Al 3104 sheet metals during cold deep drawing. Focusing on the nose plunger radius and coefficient of friction at a fixed speed and temperature (25 °C), five different scenarios are utilized to simulate the optimum parameters. Through a detailed strain history analysis from simulations, the initiation of bending in the corner is precisely identified, with a validation achieved through a strain analysis obtained via digital image correlation. The study delves into the influence of strain and strain rate on the microstructures and mechanical properties near the corner region. It highlights the superior efficacy of strain-based criteria in characterizing deformation behavior. Notably, the strain distributions during the onset of bending and severe bending align remarkably well with the established simulation data. In brief, this work introduces an integrated approach that harmoniously combines computational simulations with empirical observations, resulting in significant ramifications for precisely comprehending and forecasting the strain distribution in metal forming operations.

Femtosecond Laser Direct Writing of Gecko-Inspired Switchable Adhesion Interfaces on a Flexible Substrate.

Biomimetic switchable adhesion interfaces (BSAIs) with dynamic adhesion states have demonstrated significant advantages in micro-manipulation and bio-detection. Among them, gecko-inspired adhesives have garnered considerable attention due to their exceptional adaptability to extreme environments. However, their high adhesion strength poses challenges in achieving flexible control. Herein, we propose an elegant and efficient approach by fabricating three-dimensional mushroom-shaped polydimethylsiloxane (PDMS) micropillars on a flexible PDMS substrate to mimic the bending and stretching of gecko footpads. The fabrication process that employs two-photon polymerization ensures high spatial resolution, resulting in micropillars with exquisite structures and ultra-smooth surfaces, even for tip/stem ratios exceeding 2 (a critical factor for maintaining adhesion strength). Furthermore, these adhesive structures display outstanding resilience, enduring 175% deformation and severe bending without collapse, ascribing to the excellent compatibility of the micropillar's composition and physical properties with the substrate. Our BSAIs can achieve highly controllable adhesion force and rapid manipulation of liquid droplets through mechanical bending and stretching of the PDMS substrate. By adjusting the spacing between the micropillars, precise control of adhesion strength is achieved. These intriguing properties make them promising candidates for various applications in the fields of microfluidics, micro-assembly, flexible electronics, and beyond.

Flexible array of high performance and stable formamidinium-based low-n 2D halide perovskite photodetectors for optical imaging

Metal halide perovskites are attracting increasing attention as photodetectors (PDs) materials due to their excellent photoelectric properties. However, integrating perovskite to realize high-resolution perovskite pixel arrays remains critical to enable practical devices. Herein, we demonstrate a high-responsivity and stable 10 × 10 flexible PDs array based on formamidinium-based quasi-2D Ruddlesden-Popper (BA)2FAPb2I7 (n = 2) (BA= butylammonium, C4H9NH3+) perovskite elements for image sensing. The high-performance (BA)2FAPb2I7 arrays are synthesized on a polyethylene terephthalate (PET) flexible substrate, on a large scale, high quality, and controllable manner by introducing Au nanoparticles to enhance film quality upon the annealing process and recrystallization by applying formamidinium chloride (FACl) post-treatment to reduce perovskite film defects, combined with an innovative SiO2-assisted hydrophilic and hydrophobic surface treatment strategy. The prepared flexible PDs arrays show excellent optoelectronic properties with high responsivity (5.9 A W−1), a detectivity of 8.2 × 1012 Jones, large on/off current ratio (up to 3 × 104), ultimate response speed (12.8 μs/10.1 μs), and wide spectral response range. In addition, the device shows outstanding mechanical stability under severe bending (θ = 120°) and excellent folding durability after thousands of bending cycles. It also exhibits excellent environmental stability with only a slight degradation of photoresponse after 100 days of storage under the ambient environment. Finally, the integrated flexible PDs arrays can be used as an effective visible light image sensor with good spatial resolution, paving a multifunctional and competitive way for future wearable sensors and artificial vision systems. One-sentence summaryLow-dimensional halide perovskite layers pixelized on a polyethylene terephthalate (PET) flexible substrate provide high performance photodetectors.

Total Focusing (TFM) for the Ultrasonic Testing (UT) of drawn arc stud welding

This article describes the results obtained applying ultrasonic testing (UT) with phased arrays (PAUT) using full matrix capture (FMC) and total focusing method (TFM) for the inspection of drawn arc stud welding. Weld studs are usually directly applied on the top of a metal slab using a dedicated welding gun. This procedure involves heating the end tip of the stud using a strong electric arc created by a positive electric current. This welding procedure shall comply to various normative requirements, but on the other side there is not a clear reference to any applicable non-destructive method (NDT) to control the quality of the weld seam. Shear connectors are normally used in concrete/steel composite structures to allow the combined action of the concrete slab and the steel profile thereby increasing both the stiffness and strength of the structure. Flaws in this connection would result in severe bending and cracking of the entire structure. This article proposes an advanced UT method to inspect the weld between shear connections and metal slab using FMC. Data acquired with FMC are processed by TFM algorithms improving image resolution, signal to noise performances and allowing 3D data imaging. The combined use of PAUT searching units and signal processing with high resolution measurement shows a great potential in industrial NDT applied to civil engineering, resulting in a more effective, reliable, and faster inspection methodology than many other methods, such as radiographic testing (RT).

Flexible and sustainable printed sensor strips for on-site, fast decentralized self-testing of urinary biomarkers integrated with a portable wireless analyzer

Flexible and sustainable electronic devices may fulfill the requirements of Sustainable Development Goals (SDGs) contained in Agenda 2030 from United Nations, however, the use of degradable and eco-friendly devices for rapid, selective and on-site decentralized monitoring of patient health status with portable systems toward diagnosis, fast decision and medical interventions is relatively new. Herein, we introduce flexible and sustainable substrates/support of degradable bio-based PLA films from renewable resources produced by casting method as a sustainable alternative to conventional petroleum-based plastics toward portable electronic devices and sensing applications. The flexible devices containing full electrochemical sensing system were built with screen-printing process on PLA sustainable substrates for on-site, rapid decentralized monitoring of molecular biomarkers in non-invasive sample. Reliable urinary dopamine and uric acid analysis with limit of detections of 0.138 µM and 0.595 µM could be performed with low-cost sustainable devices (<US$ 0.08 per unit) in undiluted human urine using a flexible sensor strip coupled with a Sensit BT portable analyzer connected via Bluetooth to a smartphone, laptop or tablet. The flexible eco-friendly sensor was highly robust against severe bending strains, reproducible and selective without interference from other compounds in human urine. The sustainable sensor response was fast within 3 min with an analytical performance comparable to the gold standard method.

High‐Resolution and Stable Ruddlesden–Popper Quasi‐2D Perovskite Flexible Photodetectors Arrays for Potential Applications as Optical Image Sensor

AbstractThe development of an efficient fabrication route to achieve high‐resolution perovskite pixel array is key for large‐scale flexible image sensor devices. Herein, a high‐resolution and stable 10 × 10 flexible PDs array based on formamidinium(FA+) and phenylmethylammonium (PMA+) quasi‐2D (PMA)2FAPb2I7 (n = 2) perovskite is demonstrated by developing SiO2‐assisted hydrophobic and hydrophilic treatment process on polyethylene terephthalate substrate. By introducing Au nanoparticles (Au NPs), the perovskite film quality is improved and grain boundaries are reduced. The mechanism by which Au NPs upgrade the photoelectric quality of perovskite is mainly revealed by glow discharge‐optical emission spectroscopy (GD‐OES) and grazing‐incidence wide‐angle X‐ray scattering (GIWAXS). To further improve the photoelectric performance of the devices, a post‐treatment strategy with formamidinium chloride (FACl) is used . The optimized flexible PDs arrays show excellent optoelectronic properties with a high responsivity of 4.7 A W−1, a detectivity of 6.3 × 1012 Jones, and a broad spectral sensitivity. The device also exhibits excellent electrical stability even under severe bending and excellent flexural strength, as well as excellent environmental stability. Finally, the integrated flexible PDs arrays are used as sensor pixels in an imaging system to obtain high‐resolution imaging patterns, demonstrating the imaging capability of the PDs arrays.

Analisis Kekuatan Pembebanan Frame Pada Meja Las

Welding machine is a machine that facilitates human work in joining metals. There are two types that are usually used by humans, namely carbide welding machines and electric welding machines. Which both have their respective advantages as a metal connector. This article is lifted from the problem that occurs in the frame or frame on the welding table which experiences severe enough bending of the top frame (head support) which can damage the table frame and the unknown load (force) received by the welding table frame so that the frame is experiencing a bend. Then a design is carried out in the form of a design drawing that can be analyzed for the strength and stress that occurs in the frame which allows researchers to know the load value that is safe to use for the frame. This article aims to reveal the value of the stress that occurs in the frame and the safety value obtained from the design results of the weld table frame structure in the form of technical drawings and structural strength analysis. This article is limited to a loading of 400 newtons. This article examines the design, simulation and stress analysis of the weld table frame structure with a capacity of 400 newtons using the finite element method or also known as Finite Element Analysis (FEA). The material used is st37 iron. Finite element analysis was carried out using a numerical system using the Autodesk Inventor Professional 2020 software. The results of the simulations and also the analysis that has been carried out show that the welding table frame structure has a stress, deformation, mass, and safety factor of 20.0755 MPa, 0.0582948 mm, 40 kg

Wearable potentiometric biosensor for analysis of urea in sweat

Herein, we introduce wearable potentiometric biosensors on screen-printed carbon electrodes (SPCEs) for on-body and on-site monitoring of urea in sweat. The biosensor architecture was judiciously designed to detect urea at different pHs and incorporate a pH sensor, thus containing polyaniline ink, urease bioink and a polyvinylchloride membrane. Urea detection could be performed in the wide range from 5 to 200 mM at pH 7.0, encompassing urea levels in human sweat. The biosensor response was fast (incubation time 5 min), with no interference from other substances in sweat. Reliable urea detection could be done in undiluted human sweat with a skin-worn flexible device using the pH correction strategy afforded by the pH sensor. The performance of the epidermal biosensor was not affected by severe bending strains. The feasibility of mass production was demonstrated by fabricating epidermal flexible biosensors using slot-die coating with a roll-to-roll technique.

Fatigue Life Calculation of Tubing for In Situ Drilling Rig

The severe bending strain that the tubing of the in-situ drilling rig is subjected to during the operation under pressure, which exceeds the elastic limit, will cause periodic plastic deformation of the tubing of the in-situ drilling rig, so that fatigue cracks will occur on the internal and external surfaces of the tubing of the in-situ drilling rig and expand rapidly, leading to the greatly shortened service life of the tubing of the in-situ drilling rig. Based on the stress analysis of the dangerous points of the tubing of the in-situ drilling rig, the relationship between the predicted and the standard measured tubing life of the in-situ drilling rig is obtained in this paper. The number of tubing cycles of in-situ drilling rig decreases sharply with the increase of internal pressure. The greater the internal pressure is, the greater the circumferential stress and uniaxial alternating stress are, which causes the number of tubing cycles of in-situ drilling rig to decrease when tubing fails. It shows that the fatigue life of tubing of in-situ drilling rig is significantly affected by internal pressure.