Material Specimens Research Articles

Comparative Analysis of the Influence of Mineral Engine Oil on the Mechanical Parameters of FDM 3D-Printed PLA, PLA+CF, PETG, and PETG+CF Materials.

Polymer materials and composites play a pivotal role in modern industry, prized for their durability, light weight, and resistance to corrosion. This study delves into the effects of mineral engine oil exposure on the mechanical parameters of 3D-printed materials created through fused deposition modeling (FDM). The research scrutinizes prototype materials under diverse environmental conditions, with a particular focus on the tensile parameters. The primary aim is to analyze and compare how mineral engine oil affects the mechanical parameters of four commonly used FDM 3D-printed materials: PLA, PLA+CF composites, PETG, and PETG+CF composites. In the case of the PLA specimens, the tensile strength decreased by approximately 36%, which, considering the 30% infill, remained acceptable. Simultaneously, the nominal strain at the point of breaking increased by 60.92% after 7 days and 47.49% after 30 days, indicating enhanced ductility. Interestingly, the PLA's Young's modulus remained unaffected by the oil. The 3D-printed PLA+CF materials exposed to 30 days of mineral engine oil displayed a substantial Young's modulus increase of over 49.93%. The PETG specimens exhibited intriguing behavior, with a tensile strength decrease of 16.66% after 7 days and 16.85% after 30 days, together with a notable increase in the nominal strain at breaking by 21.34% for 7 days and 14.51% for 30 days, signifying enhanced ductility. In PETG material specimens, the Young's modulus increased by 55.08% after 7 days and 66.27% after 30 days. The PETG+CF samples initially exhibited increases in tensile strength (1.78%) and nominal strain at breaking (6.08%) after 7 days, but later experienced an 11.75% reduction in the tensile strength after 30 days. This research underscores the critical role of material selection in oil-exposed environments and suggests avenues for future exploration, encompassing microstructural analysis, the long-term impact of oil exposure, and broader considerations related to environmental and oil-specific factors. It contributes to a deeper understanding of the intricate interactions between polymer materials and mineral engine oil, offering valuable insights that can enhance industrial applications.

Effect of layering strategy and prolonged water aging on masking ability of composite resins

Statement of problemLayered composite resins may adequately mask discolored substrates. However, whether color changes that occur over time affect masking ability is unclear. PurposeThe purpose of this in vitro study was to investigate the effect of layering and water aging on the masking ability of 2 composite resins. Material and methodsDisk specimens (1.5 mm-thick and shade A1) from Charisma Diamond (CD) and Filtek Z350XT (Z350) were made according to the composite resin shade combination used in the layering strategies: bilayer for CD (enamel/dentin) and for Z350 (enamel/body and enamel/dentin) and trilayer for Z350 (enamel/body/dentin) (n=5). Color measurements were obtained with a spectrophotometer over an A3.5 ceramic substrate, and the whiteness index for dentistry (WID) was calculated. The specimens were aged in water at 37 °C and evaluated at different times: 24 hours, 1 week, 1 month, 2 months, 6 months, 12 months, 18 months, and 24 months. CIEDE2000 color differences (ΔE00) and WID differences (ΔWID) were calculated and interpreted by 50:50% color and whiteness perceptibility and acceptability thresholds. Changes among strategies and aging times were analyzed using the Kruskal-Wallis test (α=.05). Contrasts were made using the Mann-Whitney U test with Bonferroni correction (α=.001). ResultsΔE00 decreased from 24 hours to 2 months of aging. From 2 months onwards, ΔE00 increased for all layering strategies and times, without significant changes in lightness for CD (P>.004). Overall, for the CD restorative system, an increase in ΔWID was observed after 1 month of aging (P<.001), while for the Z350 restorative system, ΔWID decreased after aging (P<.001), except for the Z350 bilayer strategy (enamel + dentin) at 1 week and 2 months (P>.004). For all layering strategies and aging times, color differences were higher than the 50:50% perceptibility threshold for ΔE00 and, after 6 months, higher than the 50:50% acceptability threshold for ΔE00 and the 50:50% whiteness acceptability threshold. ConclusionsThe ability of the tested composite resins to mask a discolored substrate was affected by the layering approach applied and by prolonged water aging.

The effect of bedding planes on the bending strength of rock-like material and evaluation of the crack propagation mechanism

Bedding planes affects various material properties, including the bending strength and the crack propagation mechanism of rocks. In this paper, laboratory studies on rock-like material specimens were conducted to investigate the effect of bedding planes on the failure and crack propagation mechanism and to reduce the effect of secondary factors on the results. To this end, semi-circular bend (SCB) specimens were prepared with two concrete mixing designs using aggregate and geopolymer concretes as materials. Next, they were subjected to compressive and three-point bending tests. The crack propagation mechanism, changes in the bending strength, maximum fracture load, relative midspan displacement, fracture energy, and fracture toughness were analyzed for the anisotropic and isotropic specimens. Also, different bedding angles were examined for the anisotropic specimens. The results revealed that bedding planes generally affected the crack propagation mechanism and changed the fracture mode from pure opening mode for the isotropic specimens to mixed modes for different bedding angles. Hence, the strength and fracture parameters were generally smaller in the anisotropic specimens than in the isotropic ones. With an increase in the bedding angle in the specimens, the maximum fracture load and the fracture surface energy increased, and the midspan displacement behaved differently. Moreover, the fracture toughness displayed an increasing trend with increasing the bedding angle in the anisotropic specimens. The rate of changes in the parameters were different for different bedding angles. This may be attributed to the changes in the stress distribution and to the fracture and crack propagation modes in the anisotropic specimens compared to the isotropic ones.

Carbon footprint evaluation of routine anatomic pathology practices using eco-audit: Current status and mitigation strategies

Because of global warming, integrating an ecological dimension to the practice of pathology is crucial, as already performed in other medical specialties. The aim of the study was to estimate the greenhouse gas emissions (GHE) of one biopsy/surgical specimen hematoxylin-phloxine-saffron (HPS) slide, one frozen section examination, and one immunohistochemistry (IHC) slide, and to propose environmentally friendly recommendations.The different steps of the pathological procedures, from sample transport to slide/block destruction, were considered for the GHE evaluation. Consumables and reagents used at each step were noted, as well as the electricity consumption of the premises/equipment, specific wastes, and staff travel. The GHE analyses were performed according to the eco-audit method.The GHE attributable to one HPS slide of a biopsy, one HPS slide of a surgical specimen, one frozen section examination, and one IHC slide were 0.589 kgCO2e (CO2 equivalent), 0.618 kgCO2e, 1.481 kgCO2e, and 0.363 kgCO2e, respectively. For a one-year activity in the pathology department, the GHE for HPS was estimated at 91,897 kgCO2e, equivalent to 422,321 km of thermal car ride. The main GHE sources were staff travel for one biopsy HPS slide (34.2 %) and one surgical specimen HPS slide (32.6 %), materials (39.1 %) and staff travel (27.2 %) for one frozen section examination, and staff travel (28.2 %) and reagents and their packaging (44.9 %) for one IHC slide.The present study highlighted the most significant sources of GHE for routine practices in a pathology department, underlining that, from pathologists to policy makers, each actor has a responsibility to implement sustainable changes.

Characterization of dynamic confinement response of potting materials at different strain rates and temperatures

A Kolsky compression bar was modified with an instrumented confining tube for characterizing dynamic confinement response of materials at various strain rates. A thin film polyvinylidene fluoride (PVDF) force transducer was designed and integrated to the confining tube for direct in-situ measurement of confining pressure when the specimen is subjected to dynamic axial compressive load such that the mean stress-volumetric strain response of the specimen material is able to be determined. An environmental chamber was also implemented to the Kolsky compression bar for characterizing dynamic confinement response of materials at different environmental temperatures. After careful calibration of the instrumental confining tube, five different potting materials (EPON 828, EPON 828 filled with glass microballoons (GMBs), Sylgard 184, Sylgard 184 filled with GMBs, and expanded polystyrene (EPS) foam) were characterized with the modified Kolsky compression bar at different strain rates and environment temperatures. The effects of strain rate and temperature on the mean stress-volumetric strain response were determined for all five potting materials. Experimental uncertainties were also presented.

Checklist of newly-vouchered annelid taxa from the Clarion-Clipperton Zone, central Pacific Ocean, based on morphology and genetic delimitation.

We present a checklist of annelids from recent United Kingdom Seabed Resources (UKSR) expeditions (Abyssal Baseline - ABYSSLINE project) to the eastern abyssal Pacific Clarion-Clipperton Zone (CCZ) polymetallic nodule fields, based on DNA species delimitation, including imagery of voucher specimens, Darwin Core (DwC) data and links to vouchered specimen material and new GenBank sequence records. This paper includes genetic and imagery data for 129 species of annelids from 339 records and is restricted to material that is, in general, in too poor a condition to describe formally at this time, but likely contains many species new to science. We make these data available both to aid future taxonomic studies in the CCZ that will be able to link back to these genetic data and specimens and to better underpin ongoing ecological studies of potential deep-sea mining impacts using the principles of FAIR (Findable, Accessible, Interoperable, Reusuable) data and specimens that will be available for all. We include genetic, imagery and all associated metadata in Darwin Core format for 129 species of annelids from the Clarion-Clipperton Zone, eastern abyssal Pacific, with 339 records.

Parametric investigation of bonded composite joints under Mode II using a new methodology based on design of experiments

ABSTRACT In the pursuit of a sustainable future with limited resources and growing environmental concerns, adhesive joining stands out as a pivotal technology for the advancement of lightweight structures. This study aims to investigate the influence of various variables on the critical strain energy release rate in mode II (GIIc) for End-Notched Flexure (ENF) bonded composite joints, employing a new methodology based on Design of Experiments (DoE) approach. Two-dimensional finite element models of the ENF bonded composite joints are developed using commercial software, with all numerical models generated via Python™ scripts linked with AbaqusⓇ. Eleven design parameters related to the specimen geometry and material properties are systematically evaluated to determine the influence of each variable on GIIc. Numerical force–displacement curves are obtained, followed by the application of the Compliance-Based Beam Method (CBBM) to estimate the critical fracture energy in mode II, represented by a numerical envelope. The influence of each parameter is assessed using the main effect (ME) metric. The top five most influential variables affecting GIIc and CBBM are identified as the adhesive’s critical strain energy release rate in mode II (GIIc), effective laminate longitudinal elastic modulus (), adhesive thickness (tA), adherent thickness (h), and pre-crack length (). Furthermore, the study highlights the epistemic uncertainty associated with the geometric variables. Despite the limitations inherent in the computational model, the Plackett-Burman method consistently proves effective in conducting sensitivity analysis of the variables in the ENF test. These findings demonstrate promising prospects for the application of this procedure in the design of composite joint structures.

The Ball-on-Three-Balls strength test: Effective volumes and surfaces for Weibull strength scaling

In order to compare the strength results of brittle materials from various testing methods or use the data for design purposes, it is essential to know the effective volume (Veff) or surface (Seff) for every loading scenario. For the Ball-on-Three-Balls-test (B3B), Veff and Seff have to be determined and investigated through Finite-Element-Analysis due to the lack of an accurate analytical description of the stress field. Through this work, the effective volume and surface of the B3B-test are made available as tabulated data for a wide range of specimen geometries and materials, along with the tools to utilize the data. A fitting model for the dependency of Veff and Seff on the Weibull-modulus for any given specimen geometry is provided. The influence of load-dependent non-linear effects on Veff and Seff is discussed. Finally, the necessity of Veff and Seff for statistical strength analysis is demonstrated through a practical example.

Correlation analysis of the gradation design parameters and mechanical performance of semi-flexible pavement

Semi-flexible pavement (SFP) has been widely used for ant-rutting performance and resistance in heavy load conditions. The asphalt mixture skeleton was the central part in the complex-skeleton material system. However, few studies have been made on the connection of asphalt mixture skeleton composition and performance on semi-flexible pavement material. Therefore, the relationship between the skeleton gradation volumetric characteristic and mechanical properties of semi-flexible pavement material was investigated. Eight gradations with different coarse aggregate contents were constituted. The mechanical performances were conducted to establish the relationship between primary gradation performance. The result shows that the porosity of the asphalt matrix and Cantabro abrasion test are related to the composition of gradation. The tensile performance, shear characteristics, and compressive strength were affected by the voids filled asphalt (VFA), porosity, and fine aggregate to asphalt ratio (FB), respectively. The Burgers model accurately reflected the creep curves of the semi-flexible pavement material specimens. The creep modulus was related to the VFA, porosity, and effective asphalt content (Pbe). The gradation design parameters of open-gradation asphalt mixtures for semi-flexible pavement materials could be obtained based on the target performance. It is possible to reduce material testing times based on the correlation analysis effectively.

Study of Using Alginate Material as an Alternative Method for Foot Orthoses Casting

Background: Orthosis molding utilizes POP Bandages, Foam Impression Box (FIB), and 3D foot scanning media. Printing with FI B produces accurate prints, consistent sizes, and fast procedures. The availability of FIB in Indonesia is still difficult due to imported goods. Alginate material dental molding material in the form of powder. Objective: To determine whether the Alginate Material specimen can be used as a Foot Orthosis molding medium referring to the gold standard based on the size difference of the positive cast, the surface condition of the negative cast, and the 3 contact areas on the positive cast. Methods: Experimental, 1 participant with normal arch, comparing the dimensions of size, shape of positive cast and negative cast and 3 contact areas using univariate and bivariate tests. Results: Specimen 1 and specimen 2 have a p value ? 0.05, which means that the size results of specimens 1 and 2 are not significantly different from the gold standard. The observation results of positive cast specimens 1 and 2 have results that are close to the gold standard. Conclusion: Alginate material specimens can be used as a medium for molding Foot Orthosis. Suggestion: Can expand the scope of research on the feet of participants who have deformities and add variables to be measured in order to get more detailed and specific results.

An investigation on tensile strength of 3D printed parts of Acrylonitrile butadiene styrene (ABS) material

Fused Deposition Modelling (FDM) components' mechanical properties reflect processing parameters' effectiveness. Tensile Strength’s parameter sequence of a FDM 3D-printed Acrylonitrile butadiene styrene (Abs) material specimen is examined. Design Expert tools were utilized to conduct a variance analysis (ANOVA) to assess tensile strength components and interactions. Four FDM processing parameters—layer thickness, raster angle, infill pattern, and infill width—are examined using the Taguchi DOE. The ASTM D638-compliant specimen measurements were compared to the 3D computer-aided design model. When there are ranges of processing parameters and no linear processing criteria, design of experiments (DOEs) become difficult to determine. Identifying the best processing parameters requires a certain number of specimens. Optimum tensile strength of ABS component was 9.22 MPa at 0.3 mm layer thickness, 60° raster angle, infill width of 0.25 mm.

A Fatigue Method in the Tension-Compression Axial Stress Control Test of Automotive Sheet Steel

Abstract Focused on the common problem of easy buckling of specimens in the tension-compression axial stress control fatigue test of automobile sheet steel, a stress fatigue test method for thickness less than 2.5 mm was proposed. For two kinds of automobile sheet materials with different strength levels and thicknesses, fatigue specimens with different widths of test section, parallel lengths, and fillet radii are designed. Without the anti-buckling device, high-cycle fatigue tests with a stress ratio Rs = −1 at different stress levels were carried out, and the shape and size of the fatigue specimens of automobile sheet materials were determined by the number of fatigue life cycles of specimens with different sizes under the same stress cycle form. The results show that for automobile sheet steel with a thickness of 1.0–2.5 mm, the recommended sizes of the uniform-gauge fatigue specimens are width of test section w = (1–3) t, parallel length Lp = (1–3) w, and fillet radius r = (3–10) t. For automobile sheet steel with a thickness less than 1 mm, because the time-displacement curve jitters during the test, it is recommended to install an anti-buckling device, specifically the anti-buckling device with mortise and tenon structure by self-design and with a flattop structure recommended by ISO 1099-2017, Metallic Materials—Fatigue Testing—Axial Force-Controlled Method.

Monotonic and cyclic response of mild, stainless, and high‐strength steels, and their welded connections

AbstractIn the last decades, a significant number of studies have been devoted to the use of high‐performance steels in construction industry, due to their superior mechanical properties. High‐performance steels include, among others, austenitic stainless steel for its large ductility and excellent toughness and high‐strength steel for its high proof stress. When several steel grades are adopted in the same structural component, welded connections between dissimilar steels have a decisive importance in the seismic performance of a dissipative member. An experimental assessment of the monotonic and cyclic response of the of S235 mild‐carbon steel, 1.4404 austenitic stainless steel and S690 high‐strength steel is presented in this paper. The experimental program concerns a series of tensile tests and low‐cycle fatigue tests in several different protocols, performed both on base materials specimens, and on welded connections between dissimilar steels. Besides the material characterization which could provide reliable data for further calibration of the numerical models, the investigation of welded connections allows assessing the feasibility of combining dissimilar steels in dissipative structures.

Comparasion of composition of brake pad hardness and wearness

This study aims to identify the most optimal material composition in achieving the best combination of hardness and wear. The experimental method was conducted using a special test bed designed to test the mechanical properties of various material compositions. The material specimens used were weighed before and after the test to calculate the wear rate by observing the change in specimen mass. The results showed that the 50:50 material composition performed significantly better than the 60:40 composition in terms of hardness and wear properties. These findings suggest that the 50:50 composition may be a superior choice in various applications where a combination of strength and wear resistance is required, such as in the manufacturing industry, materials engineering, or the automotive sector. This research provides valuable insights into material selection that can improve the performance and durability of the final product.

High cycle fatigue behavior of spot welds in DP 780, TRIP 780 and DC04 steel

In this study, a methodology was successfully developed and validated to evaluate the behavior of spot welded joints of DP780, TRIP780 and DC04 steels in high cycle fatigue. Test specimens were made with three spot welds and Wohler curves were developed using the uniaxial tensile/traction load adopting the Owen R90C90 method. The spot welds showed an increase in fatigue life and a reduction in the maximum load, similar to steels. The influence of mechanical strength and material thickness tested and the types of fractures that occurred were compared. In low cycle regions, spot welds showed greater dispersion at maximum loading, between the different materials, and in higher cycle regions, this dispersion was reduced. The results obtained by adopting this method using three spot welds showed greater repeatability and less variation between the specimens of the same material. This developed method can be used with increased reliability to develop automotive bodies and spot welded components.

Intervertebral Canals and Intracanal Ligaments as New Terms in Terminologia anatomica.

This study addresses the cervical part of the vertebral column. Clinical pictures of dystrophic diseases of the cervical part of the vertebral column do not always correspond only to the morphological changes-they may be represented by connective tissue formation and nerve and vessel compression. To find out the possible reason, this morphometric study of the cervical part of the vertebral column in 40 cadavers was performed. CT scans were performed on 17 cadaveric material specimens. A total of 12 histological samples of connective tissue structures located in intervertebral canals (IC) were studied. One such formation, an intracanal ligament (IL) located in the IC, was found. Today, there is no term "intervertebral canal", nor is there a detailed description of the intervertebral canal in the cervical part of the vertebral column. Cervical intervertebral canals make up five pairs in segments C2-C7. On cadavers, the IC lateral and medial apertures were 0.9-1.5 cm and 0.5-0.9 cm, correspondingly. According to our histological study, the connective tissue structures in the IC are ligaments-IL. According to the presence of these ligaments, ICs were classified into three types. Complete regional anatomy characterization of the IC of the cervical part of the vertebral column with a description of its constituent anatomical elements was provided. The findings demonstrate the need to include the terms "intervertebral canal" and "intervertebral ligament" in the Terminologia anatomica.

Diagnostic clues for hyalinizing trabecular tumor on fine needle aspiration cytology.

The hyalinizing trabecular tumor (HTT) is a rare benign neoplasm of the thyroid gland. This neoplasm has overlapping cytological features with Papillary Thyroid Carcinoma, Medullary Carcinoma and Follicular Neoplasm with Nuclear Features of Papillary Carcinoma. This can lead to misdiagnosis of malignancy in fine needle aspiration (FNA) cytology specimens with unnecessary total thyroidectomy. The aim of this study is to determine if there are some cytological features that could help us to suspect HTT on FNA specimens and avoid radical surgery. With this purpose we have collected 6 cases diagnosed of HTT in Hospital Clínico San Carlos of Madrid (Spain) in the last 10 years and reviewed the cytological specimens. We conclude that the presence of hyaline material in FNA specimens of HTT is a constant feature being a diagnostic clue. We must be cautious not to confuse it with dense colloid or amyloid material, the latter seen in Medullary Carcinoma. Papillary architecture and fibrovascular cores are not present in a HTT. Special stains as ki-67, calcitonin and Congo Red staining could help us in achieving the correct diagnosis. We feel the cytopathologists must be aware of the distinguishing features of this lesion, mainly the typical hyaline material to achieve a proper diagnosis and be able to reduce unnecessary aggressive management of these patients.

Experimental Investigation of the Pyrolysis of Synthetic Materials Exposed to External and Internal Fires

Consideration was given to the issue of flammability during the thermal decomposition of synthetic materials used for the constructions to isolate the process equipment and building structures. The experimental research data obtained for the thermal decomposition of synthetic materials with the measurements of temperature as a function of the time of thermal radiation were given including a change in the mass and structure of the specimens of synthetic materials exposed to the thermal radiation during the fire. The obtained experimental data enabled the substantiation of the process of the thermal decomposition of synthetic materials depending on time and temperature and also a change in the mass of the specimens of synthetic materials before and after the tests.

Color stability of nanohybrid and microhybrid composites after immersion in common coloring beverages at different times: a laboratory study

Objective/AimThis in vitro study aimed to evaluate the color stability of microhybrid and nanohybrid restorative composites after exposure to immersion media common in Yemen for different periods.Materials and methodsTwo composite materials, nanohybrid Tetric N-Ceram and microhybrid Te-Econom Plus, were investigated. Six groups of 30 cylindrical specimens (n = 5/group; diameter, 10 mm; thickness, 2 mm; shade A2) of each restorative material were immersed for 1 week in distilled water, qat solution, Yemeni coffee, traditional Yemeni coffee (qishr), red tea, and Dilsi cola. Color changes were evaluated by colorimetry. The color data and pH were measured before and 1, 3, and 7 days after immersion. The data were statistically analyzed.ResultsTetric N-Ceram showed lesser discoloration than did Te-Econom Plus. Qat, coffee, and red tea caused highly significant discoloration than did Dilsi cola and distilled water (p < 0.05). The role of low pH in discoloration depended on the colorant.DiscussionNanohybrid Tetric N-Ceram composites are more resistant to discoloration than are microhybrid Te-Econom Plus composites. Qat and coffee have the highest effect on composite discoloration.ConclusionsThese findings will aid in selecting composite materials and patient instruction.

Experimental and Numerical Prediction of Surface Crack Growth in Fatigue in a Finite Width Plate

In the thick components such as gas turbine disks, the cracks usually manifest in the form of part-through or embedded elliptical cracks. The shape of surface crack varies during the crack propagation and significantly affects the fatigue life predictions of the surface cracked components. In present work, crack propagation of semi-elliptical cracks in a finite width specimen of a gas turbine material subjected to fatigue load has been studied experimentally and numerically. The numerical simulation was accomplished by first extending the applicability of available stress intensity factor empirical equation for semi-elliptical cracks to finite width solid. Using this empirical equation for stress intensity factor, the effect of change in the crack shape on the crack propagation life is simulated by numerical models. Also, in order to include the effect of crack closure in the numerical prediction of growth of surface cracks, a ratio of crack closure factor between depth and surface locations of a semi-elliptical crack was obtained by experiments. The experimental observations were used in correlating the numerical predictions for crack shape progression and crack propagation life.