Full Penetration Research Articles

Thermoplastic RTM: Impact Properties of Anionically Polymerised Polyamide 6 Composites for Structural Automotive Parts

This study investigates the impact behaviour and post-impact performance of polyamide-6 glass fibre reinforced composites, manufactured by thermoplastic resin transfer moulding. Impact test samples were extracted from quasi-isotropic laminates using two different glass fibre sizings, both with a fibre volume fraction of approximately 52%. A previous study showed that one of these sizings enhanced the interfacial strength and Mode I fracture toughness; however, the effects of the sizing on out-of-plane impact is of greater significance in terms of automotive applications. A drop-weight impact tester was used to determine out-of-plane impact performance for both sizings in terms of impact load-induced and energy returned from the striker. High-speed video of the impact response was simultaneously captured. Testing was carried out at three impact energy levels: two sub-penetration and one full penetration. The impact damage area was observed, and the post-damage compression properties of samples were measured to determine the reduction in their strength and stiffness. Results showed that the use of different sizing technologies had little effect on the post-impact compressive properties and that penetration led to only a 29% drop in compression strength. Overall, the outcomes of this work demonstrate the potential of these materials in automotive applications.

Resistance prediction of laminates, fillet‐welded and full penetration‐welded bolted T‐stub connections

AbstractBolted end plate connections are usually considered an optimal alternative in rigid‐frame steel design because they have competitive costs and good structural behaviour. The characterization of this type of connection is defined by the moment‐curvature relationship in terms of strength, stiffness and ductility, and the method of components is the analytical procedure proposed by the Eurocode standard to predict the rotational behaviour. The T‐stub is the component that idealizes the transfer of tensile forces in components of the column flange and the endplate in bending components and is composed by one T‐shape element made of a web in tension joined to a flange in bending. The connection between the web and the flange can be set continuously (in rolled profiles) or welded, and the type of welding procedure considered, fillet or by full penetration, depends on the type of loads that the connection is submitted. e.g., in the case of dynamically loaded structures, in machinery supports or structures emplaced on seismic zones, is recommended the use of full penetration to avoid a premature failure by fatigue.This paper exposes the study results of the influence of the three types of connections between the web and the flange in T‐stub connections. Monotonic loading tests, applied by a universal test machine and analysed by the Digital Image Correlation technique, have been performed at laboratories of the Pontificia Universidad Católica del Perú. Results, represented by Force‐displacement characteristics curves and strains and stresses fields, are compared with the evaluation of analytical formulae, and the results of a FEM model developed to analyse the component. The conclusions are that the type of connections between the web and the flange greatly influences the T‐stub behaviour. Currently, the bibliography defines specific values for the variable m (defined as the equivalent distance from the centre of a fastener to the plastic hinge form near to the web face) for cases of laminated or fillet welded T‐stub connections. However, there is no prescription to analyse the structural behaviour of T‐stub welded by full penetration. We recommend a deeper study for this typology of connections to propose additional values in future versions of the Eurocodes.

Pseudo‐dynamic testing of a full‐scale two‐storey steel building with RBS connections

AbstractAfter the earthquakes of Kobe (1995) and Northridge (1994) many research efforts have focused the attention on the seismic behaviour of partial strength beam‐to‐column joints because, in these seismic events, brittle fractures of welds of full‐strength joints belonging to MRFs have been observed. One of the most popular solutions developed in the aftermath to overcome the drawbacks of the typical welding joint details consisted in the adoption of the so‐called Reduced Beam Section (RBS) strategy. With this strategy beam ends are weakened into areas located sufficiently far from the column in order to reduce the stress concentration in the welds. Nevertheless, while many experimental efforts have been devoted to this connection typology, the available experimental results on full‐scale structures are still quite limited.Within this framework, aiming to provide a contribution to fill this knowledge gap, an experimental program concerning the pseudo‐dynamic testing of a full‐scale two‐storey steel building equipped with five different connection typologies is currently undergoing at the University of Salerno. In this paper the results of the first experimental campaign, dealing with MRFs with RBS connections, are presented. The mock‐up has been subjected to a sequence of seven accelerograms and the results have confirmed that, if properly designed, RBS connections provide large energy dissipation capacity and plastic rotation supply. Nevertheless, the failure of welds due to damage accumulation can be still possible, even adopting full penetration butt joint welding details conforming to Eurocode 3 and Eurocode 8 provisions.The experimental results have been complemented with numerical analyses developed with the software SeismoStruct. The comparisons between the numerical simulations and the experimental results show that the applied mixed distributed and concentrated plasticity approach, based on the adoption of phenomenological spring models, can capture accurately the global response of the structure, but it predicts with lower accuracy the local response parameters.

Conventional and Advanced Glazing Technologies for Enhancing Thermal and Lighting Performance

Glass is one of the oldest man-made material that is widely used in architecture. As it is a translucent material, it permits a full penetration of direct sunlight but may also increase the internal space temperature and then increasing cooling loads and energy consumption. As the need for energy optimization is very important and glazing is considered a weak point in any building, the selection of glazing assumes tremendous significance. This paper reviews the different types of glazing which can be categorized into conventional and advanced to optimize the thermal and the lighting performance according to their properties and insulation values. Conventional glazing includes the clear glazing whether it is single double or triple, the tinted glazing, the reflective glazing, and the low-E glazing. Advanced glazing which is mainly the insulated glazing unit such as the gas filled glazing, the vacuum glazing, the aerogel glazing and the phase change material glazing.

Puesta al día en distrofia muscular de Duchenne

Duchenne muscular dystrophy, DMD*(ICD-9-C: 359.1; ICD-10-ES: G71.01, ORPHA: 98896) is a dystrophic type, autosomal recessive myopathy linked to the X chromosome, low incidence 1/3300, with full penetrance and multi-organ involvement (neuro-muscular, respiratory, digestive and metabolic). It has great clinical variability. Symptoms begin in pediatric age (mobility limitation and early respiratory complications). Respiratory complications reduce the life expectancy of those affected. There is no treatment that modifies its evolution, although corticosteroids and new gene therapies are increasing the half-life of this disease. The role of the Primary Care Physician (PCP) is decisive in the monitoring and control of the complications of DMD, either coordinating the different specialties involved in it.

Influence of Heat Inputs on Weld Profiles and Mechanical Properties of Carbon and Stainless Steel

This study examines the effect of heat input on the weld bead profile, microstructure and mechanical properties of single V- joint welded carbon and stainless-steel plates. The as-received sample steel plates were sectioned into eight pieces; dimension 75 X 30 X 10 mm thicknesses. Shielded metal arc welding (SMAW) of heat inputs 1250 and 2030 J/mm was used to produce full penetration bead on the plates. Although visual inspection indicated that some of the welds were macro defect free, austenitic stainless steel exhibited more weld distortions than the carbon steel and this was partially attributed to its lower carbon content and the width to depth aspect ratio of the weld profile aside the magnitude of the induced stress. For the carbon steel, as the heat input increased, the hardness value of both the heat affected zone and fusion zone increased. In contrast, for stainless steel, the hardness values were reasonably comparable within same weld region (HAZ or FZ) irrespective of heat input. Furthermore, the ultimate tensile strength of the stainless steel decreased as heat input increased while the ductility increased with an increase in heat input, in contrast to carbon steel, where both ductility and ultimate tensile strength generally decreased.

Cost analysis of eye bank versus surgeon prepared endothelial grafts

BackgroundSelective lamellar corneal transplantation (keratoplasty) has overtaken full thickness penetrating keratoplasty as the graft choice for endothelial failure. Even more recently eye bank prepared tissues are becoming increasing popular as a way to reduce the risks of tissue loss and stress during endothelial keratoplasty preparation in the surgical theatre. This study compares costs between surgeon and eye bank prepared tissues for Descemet’s stripping automated endothelial keratoplasty (DSAEK) and Descemet’s membrane endothelial keratoplasty (DMEK).MethodsRetrospective study conducted at the Royal Liverpool University Hospital including endothelial keratoplasties with a minimum of 6 months follow-up time. Cost analysis included surgical expenses, tissue acquisition fees, cost of patient’s ward admission and out-patient expenses, including cost of re-bubbling procedures, costs of visits, anterior segment imaging and optometrist visits within the first 6 months follow-up.ResultsNinety-eight eyes of 98 patients were included in the study of which 42 underwent DSAEK surgery and 56 DMEK surgery. Cost analysis of surgical expenses in the DSAEK group showed a significant difference between using surgeon prepared and eye bank prepared tissue (£3866 ± 296 and £4389 ± 360, respectively; p < 0.01) and the same was found in the DMEK group (£3682 ± 167 and £4162 ± 167 for surgeon prepared and eye bank prepared tissues, respectively; p < 0.01). Cost of out-patient visits did not differ significantly in either group.ConclusionsAt the Royal Liverpool University Hospital, eye bank prepared tissues had higher surgical expenses compared to those prepared by the surgeon, while the post-operative care expenses were similar between the two groups.

Evidence That the Etiology of Congenital Hypopituitarism Has a Major Genetic Component but Is Infrequently Monogenic.

PurposeCongenital hypopituitarism usually occurs sporadically. In most patients, the etiology remains unknown.MethodsWe studied 13 children with sporadic congenital hypopituitarism. Children with non-endocrine, non-familial idiopathic short stature (NFSS) (n = 19) served as a control group. Exome sequencing was performed in probands and both unaffected parents. A burden testing approach was used to compare the number of candidate variants in the two groups.ResultsFirst, we assessed the frequency of rare, predicted-pathogenic variants in 42 genes previously reported to be associated with pituitary gland development. The average number of variants per individual was greater in probands with congenital hypopituitarism than those with NFSS (1.1 vs. 0.21, mean variants/proband, P = 0.03). The number of probands with at least 1 variant in a pituitary-associated gene was greater in congenital hypopituitarism than in NFSS (62% vs. 21%, P = 0.03). Second, we assessed the frequency of rare, predicted-pathogenic variants in the exome (to capture undiscovered causes) that were inherited in a fashion that could explain the sporadic occurrence of the proband’s condition with a monogenic etiology (de novo mutation, autosomal recessive, or X-linked recessive) with complete penetrance. There were fewer monogenic candidates in the probands with congenital hypopituitarism than those with NFSS (1.3 vs. 2.5 candidate variants/proband, P = 0.024). We did not find any candidate variants (0 of 13 probands) in genes previously reported to explain the phenotype in congenital hypopituitarism, unlike NFSS (8 of 19 probands, P = 0.01).ConclusionOur findings provide evidence that the etiology of sporadic congenital hypopituitarism has a major genetic component but may be infrequently monogenic with full penetrance, suggesting a more complex etiology.

Closed-loop control of medium-thickness plate arc welding based on weld-face vision sensing

In one-side welding with full penetration, the use of backing strips helps support molten weld metals, but increases manufacturing cycle time and cost. The backing-free welding technology is under investigation for medium-thickness structural components in the aerospace industry. Its crucial challenge is ensuring complete joint penetration and maintaining a suitable and stable backside bead width. This paper presents an innovative method of controlling weld formation based on weld-face vision sensing in arc welding. A standard laser triangulation setup is used to obtain images of weld pool, and a new weld-face feature ‘depression degree of the weld pool’ is proposed. An image processing procedure is developed to extract the depression degree of the weld pool from images in real-time. The depression degree of the weld pool is found to correlate closely with the backside bead width, and is a better indicator of the backside bead width than the weld pool width, with a higher consistency and a smaller time lag. Employing the depression degree as a feedback signal, a backside bead width control method is developed and implemented. Welding experiments on 6-mm-thick aluminum alloy 2219 plates show that the presented method is remarkably effective in achieving full penetration and keeping backside bead width constant.

Effect of heat input on microstructure and mechanical properties of GH159 and GH4169 dissimilar joints by laser beam welding

Co-based superalloy GH159 and Ni-based superalloy GH4169 have been successfully joined by laser beam welding and the effect of heat input on microstructure and properties of dissimilar joints were investigated systematically. The results showed that weld seams exhibited a nail shape and full penetration was attained at all dissimilar joints. Increasing grain size towards the fusion zone (FZ) were observed in the heat affected zone (HAZ) on the GH159 side while an increasing dissolution of γ′ and γ′ towards the FZ was attained at the HAZ on the GH4169 side. These resulted in decreasing microhardness towards FZ. Tensile failure was found in the FZ with the lowest microhardness. Meanwhile, the ultimate tensile strength (UTS) of the dissimilar joints increased with the decreasing of heat input. The high UTS of dissimilar joint with low heat input can be ascribed to the lower volume fraction of the Laves phase and the smaller dendrite arm spacing.

Mechanical and Metallurgical Properties of CO2 Laser Beam INCONEL 625 Welded Joints

In the frame of the circular economy, welding of Ni-based superalloys has gained increasing importance when applied, for instance, to repairing highly expensive components widely used in strategical sectors, such as the defense and aerospace industries. However, correct process parameters avoiding metallurgical defects and premature failures need to be known. To reach this goal, Inconel 625 butt-welded joints were produced by CO2 laser beam welding and different combinations of process parameters. The experimental investigation was carried out with three parameters in two levels with an L4 orthogonal array. Laser power, welding speed, and shielding gas flow rate were varied, and the results were reported in terms of mechanical properties, such as microhardness, tensile strength, distortion, residual stress, and weld bead geometry, and metallurgy. At a lower welding speed of 1 m/min, the full penetration was observed for 3.0 kW and 3.3 kW laser powers. However, sound welds (porosity-free) were produced with a laser power of 3.3 kW. Overall, the obtained full-penetration specimens showed a tensile strength comparable with that of the parent material with residual stresses and distortions increasing with the increase in heat input.

High-fat diet associated sensitization to metabolic stress in Wfs1 heterozygous mice

Wolfram syndrome is a rare autosomal recessive disorder caused by mutations in the wolframin ER transmembrane glycoprotein (WFS1) gene and characterized by diabetes mellitus, diabetes insipidus, optic atrophy and deafness. In experimental models the homozygous Wfs1 mutant mice have a full penetrance and clearly expressed phenotype, whereas heterozygous mutants have a less-pronounced phenotype between the wild-type and homozygous mutant mice. Heterozygous WFS1 mutations have been shown to be significant risk factors for diabetes and metabolic disorders in humans. In the present study we analyzed the response of heterozygous Wfs1 mice to high fat diet (HFD) by exploring potential outcomes and molecular changes induced by this challenge. The HFD treatment increased the body weight (BW) similarly both in Wfs1 wild-type (WT) and heterozygous (HZ) mice, and therefore HFD also prevented the impaired BW gain found in Wfs1 mutant mice. In Wfs1HZ mutant mice, HFD impaired the normalized insulin secretion and the expression of ER stress genes in isolated pancreatic islets. These results suggest that Wfs1HZ mice have a decreased insulin response and pronounced cellular stress response due to a higher sensitivity to HFD as hypothesized. In Wfs1HZ mice, HFD increased the expression of Ire1α and Chop in pancreas and decreased that of Ire1α and Atf4 in liver. The present study shows that HFD can disturb insulin function with an increased ER stress in Wfs1HZ mice and only one functional Wfs1 gene copy is not sufficient to compensate this challenge. In conclusion, our study indicates that quantitative Wfs1 gene deficiency is sufficient to predispose the carriers of single functional Wfs1 copy to diabetes and metabolic syndrome and makes them susceptible to the environmental challenges such as HFD.

Multi-keyhole separation during multi-spot laser welding of duplex steel

Separated keyholes generated during a multi-beam laser welding process were observed, analyzed, and quantified. Two high-speed cameras were utilized to capture process phenomena of bead on plate experiments, with a near vertical and a horizontal view. The films were analyzed for: the ability to form a unique keyhole for each beam, the time and location of observed fully penetrated keyhole, and other associated trends. The number of beams was correlated to fully penetrated, separate keyholes. Keyhole separations were observed to be stable while full penetration was less regular. The location of a fully penetrating keyhole correlated with the position of the stronger beam. The dynamic melt wall width separating the keyholes was measured with beam orientation and power ratios between beams having a significant impact. Beam orientation showed that the lagging inter-keyhole wall of a quad-beam process was impacted by the presence of a fully molten front in the in-line beam arrangement. For the cross-beam orientation, the lagging wall did not seem impacted by the melt front. Large power differences between leading beams for the quad-beam, in-line orientation formed a melt column in the location of the weaker beam and spattering from the column.

Water Ice Detection Research in Utopia Planitia Based on Simulation of Mars Rover Full-Polarimetric Subsurface Penetrating Radar

The probe of China’s first Mars exploration mission, Tianwen-1, has been successfully launched. It will carry out scientific exploration on the topography, soil characteristics, water ice, climate, ionosphere, and physical fields of Mars. Different from other rovers landing on the moon and Mars, the Zhurong rover is equipped with a full polarimetric subsurface penetrating radar (FP-SPR) system for the first time. The radar’s mission is to depict the shallow subsurface structure of Mars and search for possible water ice. Therefore, in this paper, a 3D realistic structure model is established and numerically simulated based on the possible subsurface structure of Utopia Planitia (the landing area). Influencing factors such as topographical fluctuations, rocks, water ice, and the variation of dielectric constant of different layers are added to the model. The analysis of the acquired FP-SPR data set shows that the two-dimensional principal component analysis (2D-PCA) method can extract effective reflected signals from the radar data with noise interference and improve the data quality. These clearly imaged targets may be water ice blocks, so the application of 2D-PCA to FP-SPR data increases the imaging quality of suspected water ice targets. The results of this paper are the basis for future processing of the measured FP-SPR data on Mars, which will help to identify more details of subsurface structures.

Crossed-Field Demagnetization of a EuBa2Cu3O7 Coated Conductor with BaHfO3 Nanorods

Superconductors can trap large magnetic fields. However, magnetic fields perpendicular to the trapped field reduces the trapped field effective, which is known as crossed-field demagnetization. Crossed-field demagnetization becomes a problem for the application of stacked magnet. We investigated the crossed-field demagnetization of a EuBa2Cu3O7 coated conductor with BaHfO3 nonorods which has large critical current density. When an AC transverse field is applied after the magnetization of the coated conductor, the decay of trapped field was significantly accelerated. However, for the AC field smaller than the full penetration field parallel to the ab-plane, the decay becomes slow enough. All these results suggests that we can apply the stacked magnet for rotating machines if the alternating transverse magnetic field is reduced below the penetration field.

Two novel variants in DYRK1B causative of AOMS3: expanding the clinical spectrum

BackgroundWe investigated pathogenic DYRK1B variants causative of abdominal obesity-metabolic syndrome 3 (AOMS3) in a group of patients originally diagnosed with type 2 diabetes. All DYRK1B exons were analyzed in a sample of 509 unrelated adults with type 2 diabetes and 459 controls, all belonging to the DMS1 SIGMA-cohort (ExAC). We performed in silico analysis on missense variants using Variant Effect Predictor software. To evaluate co-segregation, predicted pathogenic variants were genotyped in other family members. We performed molecular dynamics analysis for the co-segregating variants.ResultsAfter filtering, Mendelian genotypes were confirmed in two probands bearing two novel variants, p.Arg252His and p.Lys68Gln. Both variants co-segregated with the AOMS3 phenotype in classic dominant autosomal inheritance with full penetrance. In silico analysis revealed impairment of the DYRK1B protein function by both variants. For the first time, we describe age-dependent variable expressivity of this entity, with central obesity and insulin resistance apparent in childhood; morbid obesity, severe hypertriglyceridemia, and labile type 2 diabetes appearing before 40 years of age; and hypertension emerging in the fifth decade of life. We also report the two youngest individuals suffering from AOMS3.ConclusionsMonogenic forms of metabolic diseases could be misdiagnosed and should be suspected in families with several affected members and early-onset metabolic phenotypes that are difficult to control. Early diagnostic strategies and medical interventions, even before symptoms or complications appear, could be useful.

Distortion Control for Dissimilar Welding of SS321 to Hastelloy C-276 with CO2 Laser Beam Butt Joints Using Taguchi Methods

The laser beam welding process is a promising technology because of its reliability and ability to automate the process easily. This study aims to analyze distortion for dissimilar laser weld joints. Hastelloy C276 and SS321 plates are joined by using the CO2 Laser beam welding. Welding current, welding speed and shielding gas flow are chosen as process parameters for preparing butt joints. Each of the factors has two levels to control the parameters of the output. Experimentation was conducted with four trails by using an L4 orthogonal array. The quality of the welds and bead geometry are verified through macrostructure examination. The Vernier height gauge was used for the measurement of distortion in the weldments. Lower the better-quality characteristic is chosen for the response. ANOVA studies identified laser power at 81%, the weld speed at 16% parameters is a contribution with a statistical of about 95%. Full penetration was observed for all the experimental trails.

Optimization of Activated Tungsten Inert Gas Welding Process Parameters Using Heat Transfer Search Algorithm: With Experimental Validation Using Case Studies

The Activated Tungsten Inert Gas welding (A-TIG) technique is characterized by its capability to impart enhanced penetration in single pass welding. Weld bead shape achieved by A-TIG welding has a major part in deciding the final quality of the weld. Various machining variables influence the weld bead shape and hence an optimum combination of machining variables is of utmost importance. The current study has reported the optimization of machining variables of A-TIG welding technique by integrating Response Surface Methodology (RSM) with an innovative Heat Transfer Search (HTS) optimization algorithm, particularly for attaining full penetration in 6 mm thick carbon steels. Welding current, length of the arc and torch travel speed were selected as input process parameters, whereas penetration depth, depth-to-width ratio, heat input and width of the heat-affected zone were considered as output variables for the investigations. Using the experimental data, statistical models were generated for the response characteristics. Four different case studies, simulating the real-time fabrication problem, were considered and the optimization was carried out using HTS. Validation tests were also carried out for these case studies and 3D surface plots were generated to confirm the effectiveness of the HTS algorithm. It was found that the HTS algorithm effectively optimized the process parameters and negligible errors were observed when predicted and experimental values compared. HTS algorithm is a parameter-less optimization technique and hence it is easy to implement with higher effectiveness.

Fatigue failure of welded details in steel bridge pylons

Multi-span suspension bridges show special structural characteristics compared with conventional suspension bridges. The mid-pylon is vulnerable to fatigue failure due to the effects of wind loads and traffic loads. In this study, based on the engineering context of the Taizhou Yangtze River Bridge, some investigations were conducted on the structural behaviour of this multi-span suspension bridge. Fatigue strength tests of two critical details on the steel mid-pylon were carried out. The two details were the butt weld of two segments near the longitudinal full penetration weld and the longitudinal full penetration weld near the diaphragm. Crack propagation was observed in the tests, and it was found that the initial crack propagation directions of the two details were different. S-N curves for these two details are not included in relevant bridge design codes, and in this study, fatigue strength values of the two details are proposed based on their fatigue tests. It is suggested that the fatigue strength value corresponding to two million-cycles for the detail of the butt weld of two segments near the longitudinal full penetration weld is 85.6 MPa, and the fatigue strength value corresponding to two million-cycle for the detail of the longitudinal full penetration weld near the diaphragm is 101.5 MPa.

I-beam-to-CHS-column moment resisting joints using passing-through plates

Conventional connections of I-beam-to-CHS-column are prone to local distortion of the tube-wall in presence of bending moment that reduce its resistance and rigidity, and limit the use of these connections in multi-storey portal frames. Elements passing-through the CHS column may be a good solution to increase the resistance and stiffness of connections between I-beams and tubular members. Passing-through I-beam-to-CHS-column joints develop important stiffness and resistance, although the profile cross-section dimensions variability raises the problem of slot clearance. An alternative consists in using passing-through plates and connect the flanges and the web of the I-beam outside the CHS-column. The plates dimensions are known with a good accuracy and the slot clearance can thus be reduced.This paper presents an experimental campaign performed on 14 passing-through plates-to-CHS-column joints tested under two loading configurations: equal hogging bending moments and opposite hogging/sagging bending moments. The first loading case is representative of gravity loads whereas the second loading case occurs under seismic actions, for instance. The main parameters investigated are the tube-wall thickness, the welding type, full and partial penetration butt welds or fillet welds, and the dimensions of the web/flange plates. The behaviour of these connections is compared to that of conventional directly welded I-beam-to-CHS-column joints. Cyclic tests have been performed for the second loading configuration (opposite bending moments). To reproduce the effect of upper storeys, one cyclic test has been performed with an additional constant compressive force acting on the column. Based on the test results, an analytical model is suggested for the evaluation of the bending resistance for both loading cases and the initial rotational stiffness for the symmetric loading case only. The load transfer mechanism between the different components of the joint, tube-wall, flange and web plates, is addressed.