Effect Of Section Thickness Research Articles

Buckling resistance of axially loaded cold-formed steel built-up stiffened box sections through experimental testing and finite element analysis

The use of cold-formed steel (CFS) built-up sections in engineering practice is widely gaining popularity due to their ability to provide sustainable solutions and optimised section design opportunities. This paper presents an experimental and numerical investigation conducted on CFS built-up stiffened box section columns under axial compression. A total of 13 new experimental tests were conducted with specimens having an overall web depth up to 550 mm. Detailed nonlinear elasto-plastic finite element (FE) models were then developed and verified against the test results. Upon verification, a parametric study involving 144 FE models was carried out to investigate the effects of section thickness, column length, and screw spacing on the buckling resistance of CFS built-up stiffened box sections. The test and finite element analysis (FEA) results were compared with the buckling resistances determined by the American Iron and Steel Institute (AISI S100) and Australian and New Zealand Standards (AS/NZS 4600). It was found that the buckling resistances determined by the AISI S100 and AS/NZS 4600 for CFS built-up stiffened box sections were conservative by 9.3% on average, compared to experimental and FEA results. Modified Direct Strength Method (DSM) design equations for predicting the buckling resistances of CFS built-up stiffened box sections were then proposed, and a reliability analysis was conducted to assess the feasibility of the proposed equations.

Web crippling resistance of cold-formed steel built-up box sections through experimental testing, numerical simulation and deep learning

This study proposes a deep-learning framework, namely a deep belief network (DBN), for investigating the web crippling resistance of cold-formed steel (CFS) built-up stiffened box sections. A total of 12 new web crippling tests are presented initially, which were carried out under interior-two-flange (ITF) and end-two-flange (ETF) loading conditions. In the experimental tests, two cross-section dimensions were considered, and the overall web depth varied from 290 mm to 550 mm. The yield strength of the specimens varied from 371.7 MPa to 643.6 MPa. The specimens were characterised by different screw spacing, varying between 50 mm and 300 mm. An elasto-plastic finite element (FE) model was developed and validated against the test results. Subsequently, a total of 1,356 data points for training the DBN were generated based on the validated FE model. When a comparison was made against the test results, the absolute percentage error of the DBN predictions was found to be around 10%. Using the DBN predictions which were based on the validated FE model, a comprehensive parametric study was undertaken to investigate the effects of section thickness, yield strength, bearing length and screw spacing on the web crippling resistance of CFS built-up stiffened box sections. New design equations for predicting the ITF and ETF web crippling resistances of CFS built-up stiffened box sections were then proposed, and a reliability analysis was undertaken to assess the feasibility of the proposed equations.

Improvement of Nodularity Value of Graphite in Ductile Iron and Its Effect on Mechanical Properties

AbstractDuctile iron is becoming popular in many industrial applications due to its comparatively high strength and a considerable amount of ductility, which is because of the presence of spheroidal graphite in the microstructure. An effort has been made to improve the nodularity value of graphite in ductile iron by varying the fineness of inoculant, that is, ferro‐silicon (Fe‐Si) and section thickness of the casting. Further, the effects on mechanical properties are also studied. The spheroidal graphite iron specimens for different inoculant treatments, such as without any inoculation, in‐mold inoculation with coarse, and fine Fe‐Si, are prepared. The results have shown that the nodularity increased with in‐mold inoculation with Fe‐Si, and for the same amount of inoculated Fe‐Si, the nodularity is higher for fine Fe‐Si. Ultimate tensile strength is also found to increase with the increase in nodularity, and maximum strength of ≈460 MPa is recorded for a specimen having in‐mold inoculation with fine Fe‐Si. Stepped bar specimens of different thicknesses are also prepared by casting with the same composition for studying the effect of section thickness, and nodularity value is found to be higher for the thinnest section and is about ≈48%.

Effect of section thickness on cavitation behaviour of selective laser sintered polyamide 12

The present study focuses on the results of cavitation resistance of samples obtained by the Selective Laser Sintering technology. All samples are made from Nylon 12 - Polyamide 12 powder, known as PA2200 in the industry, produced by EOS GmbH. The powder, which has been used for building of samples, represent mixture of 50% new powder and 50% of the recycled powder. In the work, samples with different section thicknesses (0.4mm; 0.8mm and 1.0mm) were subjected to the ultrasonically induced cavitation test method to investigate the effect of geometry on their cavitation behaviour. The change in mass loss during different cavitation times was measured on the tested samples. The morphology of cavitation damage was characterized using Scanning Electron Microscopy (SEM). Results obtained in this paper have shown that section thickness of the samples have a significant influence on the cavitation resistance. The highest cavitation resistance was obtained for the samples with 0.4mm thickness.

Effects of Section Thickness on Volumetric Porosity in Aluminum Die Casting: A Case Study

Effects of Section Thickness on Volumetric Porosity in Aluminum Die Casting: A Case Study

Effect of section thickness on microstructure and mechanical properties of compacted graphite iron for diesel engine applications

Compacted (vermicular) graphite iron (CGI) is used in many substantial applications because its vermicular microstructure has superior mechanical properties at higher temperatures. Production of vermicular graphite cast iron diesel engine cylinder block with various sections’ thicknesses is a great challenge especially, if compacted graphite iron is made by controlling the pouring duration. Investigations on microstructure and hardness have been conducted on four different thicknesses (5, 10, 15, and 20 mm) of compacted graphite iron. Results demonstrated that pouring duration affects both cooling rate, and Mg/S content. These two parameters to decide the nodularity percentage and the matrix microstructure. Longer pouring duration lowers Mg/S content and decreases the cooling rate for the similar section thickness, however shorter pouring duration acts in the opposite direction. Microstructure and hardness are also affected by casting sections with the same pouring duration through different cooling rates. An increase in the cross-sectional thickness for the same pouring duration decreases the rate of cooling that encourages the formation of compacted graphite with pearlitic rather than martensitic a matrix in addition to lowers the nodular graphite count. Magnesium fading and compacted graphite ratio increased with longer pouring duration. Hardness decreased with larger section thickness and longer pouring duration due to the elimination of the martensite phase in the matrix.

Laser Capture Microdissection-Based RNA Microsequencing Reveals Optic Nerve Crush-Related Early mRNA Alterations in Retinal Ganglion Cell Layer.

PurposeTo establish a method of laser capture microdissection (LCM) and RNA microsequencing for exploring optic nerve crush (ONC)–related early mRNA alterations in retinal ganglion cell (RGC) layer.MethodsAn LCM protocol was developed using retinal tissue sections to obtain high-quality RNA for microsequencing. Cells in the RGC layer were collected by laser pressure catapulting (LPC) using a PALM Zeiss UV LCM system. The effect of section thickness and slide type on tissue capture success and RNA yield and the integrity after LCM were evaluated. The optimal LCM protocol was used to explore ONC-related early mRNA alterations in the RGC layer. Candidate genes were validated by real-time polymerase chain reaction of the RGC layer tissue dissected by “cut and LPC” using the same LCM system.ResultsWe successfully established an optimal LCM protocol using 30-µm–thick retinal tissue sections mounted on glass slides and laser pressure catapulting (LPC) to collect cells in the RGC layer and to obtain high-quality RNA for microsequencing. On the basis of our protocol, we identified 8744 differentially expressed genes that were involved in ONC-related early mRNA alterations in the RGC layer. Candidate genes included Atf3, Lgals3, LOC102551701, Plaur, Tmem140, and Maml1.ConclusionsThe LCM-based single-cell RNA sequencing allowed a new sight into the early mRNA changes of RGCs highlighting new molecules associated to ONC.Translational RelevanceThis technique will be helpful for more accurate transcriptome analysis of clinical pathological samples of ophthalmology and provide important reference for the discovery of new pathological diagnosis indicators and drug development targets.

Is it possible to estimate volume of bone defects formed on dry sheep mandibles more practically by secondarily reconstructing section thickness of cone beam computed tomography images?

The purpose of this study was to evaluate the effect of section thickness on volume estimations of bone defects scanned using cone beam computed tomography (CBCT). 25 bone defects were prepared on sheep mandibles and scanned using a KaVo 3D eXam (KaVo Dental, Biberach, Germany) CBCT device. Section thickness of images were reconstructed at 0.25, 0.5, and 0.75 mm to estimate the volume of these defects using the semiautomatic segmentation method. The volume averages obtained using microcomputed tomography and Archimedes' method served as reference values. The estimated volumes at each section thickness were compared with the actual volumes using the Friedman test. The accuracy of volume estimation was determined by the percentage error with respect to the reference values, and the mean absolute error (MAE) was calculated. Volumetric values of bone defects obtained with CBCT at section thicknesses up to 0.5 mm were compatible with the actual volumes (p > 0.05). The percentage errors at section thicknesses of 0.25, 0.5, and 0.75 mm were -5.4%, -7.3%, and -13.1%, respectively. The mean absolute errors were 13.6 mm3, 15.7 mm3, and 18.2 mm3, respectively. The section thickness values of CBCT images can be increased to a reasonable level to obtain accurate volume estimation results and save time. The semiautomatic segmentation method can be used reliably for volume estimations of bone defects.

Effect of section thickness on cone beam computed tomography-based measurements of intrabony defects compared with clinical measurements.

It is unknown whether cone beam computed tomography (CBCT) image reconstruction characteristics, including section thickness, may affect linear bone measurements of periodontal intrabony defects. The aim of this study was to compare intrasurgical and CBCT-based linear measurements of intrabony defects focusing on CBCT section thickness. Sixty-six intrabony defects were assessed in 21 patients with chronic generalized severe periodontitis. Linear measurements of alveolar bone (radiographic bone level [rBL]), assessed in CBCT images at diverse section thicknesses: 0.25mm (voxel size), 1mm, and 3mm, were compared with clinical bone level (cBL) measurements obtained intrasurgically. To provide identical reference points for rBL and cBL measurements, individually adjusted grooves on the reference stent were prepared for each periodontal defect site. CBCT measurements were performed in two rounds by two trained observers. Observer agreement was assessed by intraclass correlation coefficients (ICC). ANOVA assessed the difference among cBL and rBL at different section thicknesses. Intra- and inter-observer agreement was excellent (ICC>0.99) and highly significant independent of the observer, evaluation round, and CBCT section thickness. Mean rBL in the diverse CBCT section thicknesses was very close to that measured clinically (cBL). There was no statistically significant difference between cBL and rBL for any section thickness, neither for the overall evaluated sites, nor the maxilla or mandible separately. No statistically significant difference between clinical and radiographic bone level for 0.25-, 1-, and 3-mm CBCT section thicknesses were observed when assessing intrabony periodontal defects.

Numerical investigation of CFRP strengthened RHS members under cyclic loading

Rectangular hollow section (RHS) steel members are commonly utilized in various mechanical and civil engineering applications, but they have shown to be quite vulnerable under cyclic loading. In both onshore and offshore infrastructure, steel members can be subjected to cyclic loading produced by earthquakes, currents, wind and waves. Considering multiple factors, such as design errors, the influence of environmental conditions, an increase in applied loads and material deterioration, steel members may require strengthening to withstand cyclic loadings. This study presents numerical simulations using finite element (FE) modelling techniques to analyse carbon fibre reinforced polymer (CFRP) strengthened RHS steel members subjected to cyclic loading to predict their behaviour and modes of failure. The predicted results are compared with available results from experimental tests to validate the numerical models and ensure their accuracy. Results imply that CFRP strengthened RHS steel members demonstrate enhanced cyclic performance in which the moment-rotation hysteresis behaviour, secant stiffness and the energy dissipating capacity are improved compared those in bare steel RHS members. Furthermore, the effects of section thickness, bond length of CFRP, number of CFRP layers, wrapping orientation of CFRP and elastic modulus of CFRP on the response of these structural members are also investigated through detailed parametric studies.

Friction stir welding of thick section reduced activation ferritic–martensitic steel

Full penetration friction stir welding was conducted on 12 mm thick reduced activation ferritic–martensitic steel at tool rotational speeds of 500 and 900 rev min−1. Comparator welds at 500 rev min−1 were also produced in 6 mm thick reduced activation ferritic–martensitic steel plate to evaluate section thickness effects. Increase in section thickness led to an increase in heat input, which strongly influenced the microstructure evolution in stir zone (SZ), thermo-mechanical affected zone and the overall hardness in the SZ of this steel. In the as-welded condition, the base metal microstructure was significantly altered and resulted in carbide-free grain boundaries. The desirable microstructure and mechanical properties were achieved by subjecting the as-welded joints to appropriate post-weld heat treatments.

Effect of Section Thickness on Heat Transfer during Quenching in Vegetable Oils

In the present work, mineral, sunflower, karanja, and neem oil were used as quench media. 304 stainless steel probes with diameters of 25 mm and 50 mm were quenched in these oils to assess the effect of section diameter on heat transfer during quenching. Cooling curve analysis was carried out by instrumenting the probes at various locations with thermocouples. The heat extraction ability of oil quench media was quantified using an inverse heat conduction method. Thermal data and the predicted hardness values showed the suitability of nonedible vegetable oils as potential quenchants to heat treat steels. The predicted hardness was higher during quenching in karanja oil compared to other oil media.

Effect of section thickness on fatigue performance of laser sintered nylon 12

Laser Sintering offers manufacturers freedom of design, which enables creating parts with complex geometries. However, very little investigation has been made into the effects of geometry on mechanical properties of the parts. In the present study, Laser Sintered Nylon 12 parts with different section thickness are subjected to displacement controlled tension-tension and force-controlled fully reversed fatigue loading to investigate the effect of geometry on their fatigue behavior. Section thickness of the parts is shown to have no significant influence on the fatigue behavior under tension only loading. However, fatigue life of parts under fully reversed loading is shown to increase with section thickness.

Microstructure and material soundness in liquid and rheocast AZ91: effect of section thickness

Rheocast and liquid cast AZ91 magnesium alloy were compared to explore the feasibility of Rheocasting commercial Mg alloys using the RheoMetal process. A close-to industrial scale squeeze casting machine was used, with a mold having rectangular shaped cavities of section thicknesses 7, 13 and 20 mm. The pore content and its distribution as well as the microstructure of the castings were analyzed. The average size of the globular primary α-phase particles in the rheocast samples was around 50 μm. The shape factor of the primary particles in the rheocast samples had a bell-shaped distribution with a peak at 0,4-0,6 while the conventionally cast material had more stochastic distributions. The porosity in the rheocast samples was coarser than in the liquid cast samples, even though both types had similar levels of overall porosity. There was a layer of segregated porosity at around 30% of the section thickness from the sample surface; severe in the liquid cast samples and slight or non-existent in the rheocast samples.

Microstructure and material soundness in liquid and rheocast AM50 and effect of section thickness

Commercial grade AM50 magnesium alloy was diecast to varying wall thickness using both the RheoMetal process and conventional liquid casting. The resulting microstructure and pore structure were analysed. The rheocast material had larger pores than the conventionally cast material, scattered over the central 50% of the cross-section, while the pores in the conventionally cast material was concentrated to a segregation band at a depth corresponding to approximately 30% of the wall thickness. In the Rheocast samples, there was a correlation between thicker sections and larger primary α-Mg globules with a lower shape factor.

Effect of Section Thickness on the Microstructure and Hardness of Ductile Cast Iron

Abstract Ductile cast irons have several engineering and manufacturing advantages compared to other cast materials such as steels. These include high damping capacity, wear resistance, to and lower manufacturing cost. The combination of good mechanical properties and casting abilities of ductile cast iron makes its usage successful in structural applications especially in the energy and automotive industries. In this study, the influence of the section thickness on the microstructure and hardness of spheroidal graphite cast iron was investigated with a cascaded model using the full mold casting method. By the high linear correlation coefficient, R2 > 0.90, it was observed that the section thickness directly affected the microstructure and hardness. An increase in the cross-sectional thickness decreases hardness and number of graphite nodules per square millimeters, however, percentage of ferrite was increased.

Investigation of surface roughness of aluminium solid mould investment castings

Solid investment moulds are used for precious or non-precious metals and alloys castings, the most common application areas are dental prosthesis and jewellery fabrications. Investment casting is known for high dimensional accuracy and smooth surface finish. Casting of ultra-thin sections and small complex parts require vacuum assisted or centrifugal filling. In this study, solid investment casting of aluminium has been tried and surface quality of the castings was investigated. Specially designed steppedwedge surface roughness specimens were produced with A413 aluminium alloy casting into gypsum bonded solid moulds. Casting operations were carried out in two ways; the first only with gravitational force and the second with vacuum assistance. Surface roughness of as cast specimens were measured, effects of section thickness, vacuum assistance and location of the pattern on the wax tree were determined.

The Effect of Slice Thickness on the Assessment of Bone Defect Volumes by the Cavalieri Principle Using Cone Beam Computed Tomography

The purpose of this study was to investigate the possible effects of section thickness on volume estimations obtained by cone beam computed tomography. Intraosseal cavities representing bone defects on vestibular sides of the two dry sheep mandibles were scanned by a cone beam computed tomography system. Consecutive sections at 0.2, 0.6, 1, 1.4, and 2.2 mm thickness were used to estimate the volumes of the cavities using the Cavalieri principle of stereological methods. Estimated volumes are then compared with the volumes obtained by the Archimedean principle. In 0.2-, 0.6-, and 1-mm-thick slices, the volumes estimated by the Cavalieri principle did not differ from the volumes by the Archimedean principle (p > 0.05). The 0.2 mm slice-thickness group had the highest asymptotic significance value (p = 0.6). Although the thinnest slice appears to provide the most accurate values, slice thickness up to 1 mm can be chosen for volume calculations on CBCT images.

Effect of slice thickness on detectability in breast CT using a prewhitened matched filter and simulated mass lesions

Dedicated breast CT (bCT) is an emerging technology with the potential to improve the detection of breast cancer in screening and diagnostic capacities. Typically, the 3D volume reconstructed from the scanner is displayed as sectional images. The purpose of this study was to evaluate the effect of section thickness on the detectability of simulated masses using a prewhitened matched filter (PWMF) as a model observer. A breast CT scanner has been designed and fabricated in the authors' laboratory with more than 200 women imaged in IRB-approved phase I and phase II trials to date. Of these, 151 bilateral data sets were selected on the basis of low artifact content, sufficient breast coverage, and excluding cases with breast implants. BIRADS breast density ratings were available for 144 of these patients. Spherical mass lesions of diameter 1, 2, 3, 5, 11, and 15 mm were mathematically generated and embedded at random locations within the parenchymal region of each bCT volume. Microcalcifications were not simulated in this study. For each viewing plane (sagittal, axial, and coronal) and section thickness (ranging from 0.3 to 44 mm), section images of the breast parenchyma containing the lesion were generated from the reconstructed bCT data sets by averaging voxels over the length of the section. Using signal known exactly (SKE) model observer methodology, receiver operating characteristic (ROC) curve analysis was performed on each generated projected image using a PWMF based model observer. ROC curves were generated for each breast data set, and the area under the ROC curve (AUC) was evaluated as well as the sensitivity at 95% specificity. For all lesion sizes, performance rises modestly to a peak before falling off substantially as section thickness increases over the range of the study. We find that the optimal section thickness tracks the size of the lesion to be detected linearly with a small positive offset and slopes ranging from 0.27 to 0.44. No significant differences were observed between left and right breasts. Performance measures are negatively correlated with measures of breast density, with an average correlation coefficient of -0.48 for the BIRADS breast density score and -0.81 for the proportion of glandular tissue in the breast interior. This study shows quantitatively how PWMF detection performance of a known lesion size is influenced by section thickness in dedicated breast CT. While the optimal section thickness is tuned to the size of the lesion being detected, overall performance is more robust for thin section images compared to thicker images.

Human skeletal muscle glycogen utilization in exhaustive exercise: role of subcellular localization and fibre type

Although glycogen is known to be heterogeneously distributed within skeletal muscle cells, there is presently little information available about the role of fibre types, utilization and resynthesis during and after exercise with respect to glycogen localization. Here, we tested the hypothesis that utilization of glycogen with different subcellular localizations during exhaustive arm and leg exercise differs and examined the influence of fibre type and carbohydrate availability on its subsequent resynthesis. When 10 elite endurance athletes (22 ± 1 years, VO2 max = 68 ± 5 ml kg-1 min-1, mean ± SD) performed one hour of exhaustive arm and leg exercise, transmission electron microscopy revealed more pronounced depletion of intramyofibrillar than of intermyofibrillar and subsarcolemmal glycogen. This phenomenon was the same for type I and II fibres, although at rest prior to exercise, the former contained more intramyofibrillar and subsarcolemmal glycogen than the latter. In highly glycogen-depleted fibres, the remaining small intermyofibrillar and subsarcolemmal glycogen particles were often found to cluster in groupings. In the recovery period, when the athletes received either a carbohydrate-rich meal or only water the impaired resynthesis of glycogen with water alone was associated primarily with intramyofibrillar glycogen. In conclusion, after prolonged high-intensity exercise the depletion of glycogen is dependent on subcellular localization. In addition, the localization of glycogen appears to be influenced by fibre type prior to exercise, as well as carbohydrate availability during the subsequent period of recovery. These findings provide insight into the significance of fibre type-specific compartmentalization of glycogen metabolism in skeletal muscle during exercise and subsequent recovery. .