Small Pin Research Articles

A critical comparison of dynamometer data with pin-on-disc data for the same two friction material pairs – A case study

Friction and wear behavior of brake materials is often investigated using Pin-on-Disc (PoD) or dynamometer tests. Dynamometer tests reproduce the real braking conditions since they are carried out on real parts. whereas PoD tests are carried out using small pins, under constant sliding velocity and contact pressure. In the present technical note, the friction and wear behavior of two commercial friction materials, a low-met and a non-asbestos organic (NAO) material, dry sliding against a pearlitic cast iron counterface disc was investigated. The PoD tests were carried out at room temperature and at 300 °C; the dynamometer tests were conducted simulating urban braking conditions. The experimental data were compared and the main wear mechanisms were identified. The wear mechanisms observed with the PoD at room temperature turned out to be similar to those observed with the dynamometer tests. On the other hand, the PoD tests carried out at 300 °C revealed particular features in the friction layer that were not detected in the dynamometric tests. As far as the tribological data are concerned, the average friction coefficients recorded during the dynamometric tests were similar to the values recorded in the PoD tests, whereas the wear coefficients were one order of magnitude lower, most probably due to the limited area of contact of the pins.

Divergent Linkage Reconfigurable Mould For Rapid Prototyping

Abstract Rapid prototyping (RP) is a manufacturing technology, where parts are built rapidly, without using traditional machining processes. Reconfigurable mould techniques are one of the rapid prototyping techniques for building parts. Mould cavity is created with the use of discrete array of movable pins. With the use of reconfigurable mould, mass customization of product can be done easily. In this article, we have discussed the basic set-up of reconfigurable mould, its mechanism, and limitations. One of the limitations of large screw size, and small pin size is discussed in detail. A proposed model of divergent linkage is discussed to solve this problem. With the use of this proposed model, pin size can be reduced for surface finish (high resolution) without reducing the lead screw size. Hence, divergent linkage is promising method to increase pin resolution and make it more valuable in industries rapid prototyping.

GE ANALYSIS MEASUREMENTS AND THEIR CORRELATIONS WITH EGG QUALITY TRAITS AND EGG CHEMICAL COMPOSITION OF DIFFERENT EGGSHELL PATTERNS OF JAPANESE QUAIL

The present study was carried out to identify the effect of colour and pattern varieties of Japanese quail eggshell on image analysis measurements for the eggshell, egg quality traits and chemical composition of whole egg components, as well as the correlations between image analysis measurements for eggshell with egg quality traits. Image analysis parameters of eggshell, egg quality traits, chemical composition for egg components were evaluated at 19 weeks of age for a total 744 Japanese quail eggs collected from 186 identified females classified by their egg shell imprints according to egg shell color and pattern into five groups of egg-type [1st group: white eggshell (Non-pigmented), 2nd group: greyish white egg shell pigmented with small black pigments spots (Black-spotted), 3rd group: small black pin dots on greyish brown shell background (Pin dotted), 4th group: slightly blue pigments (Sandy gray), 5th group: brown eggshell with heavily dark pigmentation (Heavily dark)]. There are significant differences (P≤0.05) between studied egg shell patterns for image analysis measurements. Sandy gray eggs had significantly the highest values, while white egg had the lowest values for all studied external egg quality traits comparing with other egg groups. No significant influence of egg shell patterns on chemical composition analysis for egg components for different gropes except moisture and fat % in white eggs (71.3 and 9.7% respectively) which were significantly lower compared to other egg shell groups. Significant correlations, whether positive or negative were found between image analysis measurements of eggshell and some egg quality traits for different studied groups which can be used in future studies.

User-oriented novel electric upper limb prosthesis with flexible sensors for detecting skin deformation

Conventional myoelectric hands need to detect muscle activities in stumps; therefore, they are not applicable in amputees with short stumps or with paralyzed limbs. We developed a novel electric upper limb prosthesis that functions without myoelectricity, based on the shape deformation of the amputated upper limb. This bioinstrument includes a bridge circuit and multiple amplifier circuits that are calibrated to amplify minute voltages from a skin sensor with multiple strain gauges placed on the soft and stretchy skin surface within a specified range of output voltages. The aim of this study is to compare the novel electric upper limb prosthesis with a conventional myoelectric hand (Myoboy system with System Electric Hand DMC plus, Ottobock). Eight healthy participants were enrolled in this study. Clinical evaluation of each hand was performed using the Simple Test for Evaluating Hand Function (STEF) and the Action Research Arm Test (ARAT). Additional tests based on activities of daily living, such as holding a ballpoint pen, grasping an eraser, holding a plastic bottle, and holding an umbrella, were also performed. Each hand was fixed to the participants’ forearm after placing sensors to detect myoelectricity or the shape deformation of the forearm. Performing the last 4 tasks of the STEF; that is, pinching small metallic circular disks, small wooden circular disks, small pins, and pieces of cloth—and the first task of ARAT; that is, grasping a big wooden block—was difficult with both prosthetic hands. The remaining tasks could be performed only with the novel prosthesis. We developed a novel prosthetic hand with unique sensors to detect skin deformation that enables better grasping than that with conventional myoelectric hands. Additional tests on activities of daily living will be effective in evaluating the function of this prosthesis.

Radius regeneration after open fracture and extrusion: a case report

Level 4; case report.

Microstructural and Electrochemical Characterization of Friction Stir Welded Aluminum Alloys

Aluminum alloys of 2000 and 7000 series containing cooper and zinc, respectively, as the main alloying element are extensively used in aircraft structures. However, these classes of aluminum alloys are difficult to join by conventional fusion welding techniques because the dendritic structure formed in the fusion zone can seriously compromise the mechanical and corrosion resistance properties of the joint. Friction Stir Welding (FSW) is attractive for joining high strength aluminum alloys since there is far lower heat input during the process compared with conventional welding methods. FSW is produced by rotating and plunging a specially-designed cylindrical, shouldered tool with a small diameter pin into the joint line between two butted plates. Frictional heat causes the metal to soften and allows the tool to traverse along the joint line [1]. The FSW process generates three distinct microstructural zones: the nugget, the thermomechanically affected zone (TMAZ) and the heat-affected zone (HAZ). These microstructural modifications generally interfere in the performance of the corrosion resistance of welded alloys. In the present study, FSW was used to join two dissimilar aluminum alloys, AA2024-T3 (Al-Cu-Mg) and AA7475-T651 (Al-Cu-Mg-Zn) and the effect of this process on the corrosion resistance of the welded joints and on the microstructure of the alloys was evaluated. Microstructural characterization was carried out by optical microscopy, scanning electron microscopy and atomic force microscopy. The weld zone regions showed significant microstructural changes. Electrochemical impedance spectroscopy (EIS) and Electrochemical noise measurements (ENM) were used to evaluate the corrosion resistance of the different zones of the weld in NaCl solution. Local electrochemical measurements using an electrochemical microcell were carried out across the transverse cross section of the welds. The cell containing the solution, counter and reference electrodes is attached to the carousel of an optical microscope. The electrochemical results showed that the corrosion behavior of the AA2024-T3 / AA7475-T651 alloy is dominated by the electrochemical activity within the intermetallics (IMs). The weld zone regions containing copper IMs have a more noble character than the regions containing Zn and Mg IMs. Therefore, the results showed an increased susceptibility of welded joints to these forms of corrosion in comparison to the unaffected base metal by a more severe attack related to AA7475-T651 alloy. Reference [1] M. Jariyaboon et al. Corrosion Science 49 (2007) 877–909. [2] J.-Q. Su et al. Acta Materialia 51 (2003) 713–729 Acknowledgement: Fapesp 2013/132356

Deposition of strontium phosphate coatings on magnesium by hydrothermal treatment: Characteristics, corrosion resistance and bioactivity

Deposition of strontium phosphate (Sr-P) coatings on magnesium using 0.1 M Sr(NO3)2 and 0.06 M NH4H2PO4 (pH: 3.00) by hydrothermal treatment at 80, 120, 150 and 200 °C for 30 min and, evaluation of its characteristic properties, corrosion resistance and bioactivity are addressed. The surface morphology of the Sr-P coatings revealed that they are uniform and compact. The coating weight, density and average surface roughness of the coating are increased with an increase in treatment temperature from 80 to 200 °C. X-ray diffraction patterns confirmed that the Sr-P coatings are highly crystalline and consisted of Mg phosphates and Sr phosphates as the major constituents along with minor quantities of Mg(OH)2 and Sr(OH)2. SrHPO4 is the predominant phase along with moderate amounts of Sr3(PO4)2 and Mg phosphate phases, when the deposition temperature is increased from 80 to 200 °C. The formation of these phases are further supported by the presence of stretching and bending vibrations pertaining to HPO42− and PO43− groups in the FT-IR and Raman spectra. The Sr-P coated Mg offered a higher corrosion resistance when compared to the uncoated Mg in HBSS. Among the Sr-P coated ones, those prepared at 200 °C for 30 min exhibited a better stability. The higher coating weight, better surface coverage, increase in crystallinity and increase in volume fraction of strontium phosphate phases are considered responsible for this behaviour. The formation of apatite phase after immersion in SBF for 240 h confirmed the bioactivity of Sr-P coated Mg. The study concludes that Sr-P coatings deposited on Mg by HT exhibit good structural integrity, higher corrosion resistance and bioactivity. It is believed that deposition of Sr-P coatings on Mg by HT is a useful surface modification approach for the development of Mg based cardiovascular stents, small pins, screws and needles.

Editorial

Editorial Drake Stutesman Framework 59.1 looks at various mediums in which creativity flourishes in unexpected ways. Television, as a vehicle for the poetic as much as for the prosaic, is examined by two writers. Ben Olin's "Reframing the New York School: Public Access Poetry and the Screening of Poetic Coterie" details the 1970s and '80s New York cable television show Public Access Poetry, which featured poets, most of whom were in emerging avant-garde literary movements, and discusses how the visual medium reflected and played with the verbal medium and how central it was to the development of the new writing. In his piece "Lyrical Television" Scott MacDonald, critic, programmer, and advocate of independent/avant-garde cinema, work that is often regarded as poetic, considers the way television also employs "lyrical," as he names it, avant-garde practices. Scholar and costume designer Lauren Boumaroun, in her essay "Costume Designer/Everything: Hybridized Identities in Animation Production," reveals the surprising world of costume design in animation, especially focusing on particular designers by exploring their experience in the workplace as well as their ingenuity in executing the task of creating outfits for stop-frame and drawn characters. One of the Framework 59.1 cover images, showing a close-up of fingers knitting a sweater on knitting needles the size of small straight pins, tells part of that story. In the section "New Looks: Film Review," in which authors reexamine a film released in the past few years, Susan Potter and Matias Perez ponder Nuri Bilge Ceylan's 2014 film, Winter Sleep, in "Melodramatic Ends: Winter Sleep (Kiş Uykusu)." [End Page 5] Copyright © 2018 Wayne State University Press

The Effects of Antimony Addition on the Microstructural, Mechanical, and Thermal Properties of Sn-3.0Ag-0.5Cu Solder Alloy

In this study, we investigated the effects produced by the addition of antimony (Sb) to Sn-3.0Ag-0.5Cu-based solder alloys. Our focus was the alloys’ microstructural, mechanical, and thermal properties. We evaluated the effects by means of scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), differential scanning calorimetry (DSC), and a universal testing machine (UTM). The results showed that a part of the Sb was dissolved in the Sn matrix phase, and the remaining one participated in the formation of intermetallic compounds (IMCs) of Ag3(Sn,Sb) and Cu6(Sn,Sb)5. In the alloy containing the highest wt pct Sb, the added component resulted in the formation of SnSb compound and small particle pinning of Ag3(Sn,Sb) along the grain boundary of the IMCs. Our tests of the Sn-3.0Ag-0.5Cu solder alloys’ mechanical properties showed that the effects produced by the addition of Sb varied as a function of the wt pct Sb content. The ultimate tensile strength (UTS) increased from 29.21 to a maximum value of 40.44 MPa, but the pct elongation (pct EL) decreased from 48.0 to a minimum 25.43 pct. Principally, the alloys containing Sb had higher UTS and lower pct EL than Sb-free solder alloys due to the strengthening effects of solid solution and second-phase dispersion. Thermal analysis showed that the alloys containing Sb had a slightly higher melting point and that the addition amount ranging from 0.5 to 3.0 wt pct Sb did not significantly change the solidus and liquidus temperatures compared with the Sb-free solder alloys. Thus, the optimal concentration of Sb in the alloys was 3.0 wt pct because the microstructure and the ultimate tensile strength of the SAC305 solder alloys were improved.

The Effects Of Critical Welding Parameters On Tensile-Shear Properties Of Friction Stir Spot Welded Polyethylene

The aim of this study was to investigate the weldability of high density polyethylene via friction stir spot welding method. Polyethylene sheets were joined with dwell times of 60 to 100 s, three different pin profiles (M6×1, M6×1.25, M6×1.5) and pin lengths of 3.75 to 4.75 mm by using rotational speed of 900 rpm and delay time of 45 s. During welding processes, the temperatures were measured under the welding centers. The tensile-shear tests were performed to welded samples. Also, macrostructures of welding nuggets were examined. The small welding nuggets were formed by using the lower dwell time. The melting in welding nugget occurred in the all dwell times during the welding. The dwell time affected on the friction temperature. The key (pin) hole closed when sufficient friction temperature (dwell times of 80 and 100 s). The pin profiles directly affected the welding quality. Large screw pitch range of the pin and the small pin length from 4.5 mm negatively affected the weld fracture load. Pin length of the stirring tool directly affected the quality of welding.

Heat Loads Due To Small Penetrations In Multilayer Insulation Blankets

The main penetrations (supports and piping) through multilayer insulation systems for cryogenic tanks have been previously addressed by heat flow measurements. Smaller penetrations due to fasteners and attachments are now experimentally investigated. The use of small pins or plastic garment tag fasteners to ease the handling and construction of multilayer insulation (MLI) blankets goes back many years. While it has long been understood that penetrations and other discontinuities degrade the performance of the MLI blanket, quantification of this degradation has generally been lumped into gross performance multipliers (often called degradation factors or scale factors). Small penetrations contribute both solid conduction and radiation heat transfer paths through the blanket. The conduction is down the stem of the structural element itself while the radiation is through the hole formed during installation of the pin or fastener. Analytical models were developed in conjunction with MLI perforation theory and Fourier’s Law. Results of the analytical models are compared to experimental testing performed on a 10 layer MLI blanket with approximately 50 small plastic pins penetrating the test specimen. The pins were installed at ∼76-mm spacing inches in both directions to minimize the compounding of thermal effects due to localized compression or lateral heat transfer. The testing was performed using a liquid nitrogen boil-off calorimeter (Cryostat-100) with the standard boundary temperatures of 293 K and 78 K. Results show that the added radiation through the holes is much more significant than the conduction down the fastener. The results are shown to be in agreement with radiation theory for perforated films.

Effect of ultrasonic nanocrystal surface modification on residual stress and fatigue cracking in engineering alloys

AbstractThe effects of ultrasonic nanocrystal surface modification (UNSM) on residual stresses and fatigue crack initiation were investigated in various engineering alloys. It was found that higher contact force and smaller pin in UNSM produced higher compressive residual stresses at the surface and subsurface of the alloys. The compressive residual stresses were found to be higher in high yield strength alloys. A deeper compressive residual stress field was observed in alloys with higher elastic modulus and strain hardening exponent. Fatigue crack initiation was found to occur subsurface in the material where the effect of UNSM hardening was saturated. It was concluded that deeper UNSM hardening produces higher fatigue life.

A cell culture technique for human epiretinal membranes to describe cell behavior and membrane contraction in vitro.

To introduce a human cell culture technique for investigating in-vitro behavior of primary epiretinal cells and membrane contraction of fibrocellular tissue surgically removed from eyes with idiopathic macular pucker. Human epiretinal membranes were harvested from ten eyes with idiopathic macular pucker during standard vitrectomy. Specimens were fixed on cell culture plastic using small entomological pins to apply horizontal stress to the tissue, and then transferred to standard cell culture conditions. Cell behavior of 400 epiretinal cells from 10 epiretinal membranes was observed in time-lapse microscopy and analyzed in terms of cell migration, cell velocity, and membrane contraction. Immunocytochemistry was performed for cell type-specific antigens. Cell specific differences in migration behavior were observed comprising two phenotypes: (PT1) epiretinal cells moving fast, less directly, with small round phenotype and (PT2) epiretinal cells moving slowly, directly, with elongated large phenotype. No mitosis, no outgrowth and no migration onto the plastic were seen. Horizontal contraction measurements showed variation between specimens. Masses of epiretinal cells with a myofibroblast-like phenotype expressed cytoplasmatic α-SMA stress fibers and correlated with cell behavior characteristics (PT2). Fast moving epiretinal cells (PT1) were identified as microglia by immunostaining. This in-vitro technique using traction application allows for culturing surgically removed epiretinal membranes from eyes with idiopathic macular pucker, demonstrating cell behavior and membrane contraction of primary human epiretinal cells. Our findings emphasize the abundance of myofibroblasts, the presence of microglia and specific differences of cell behavior in these membranes. This technique has the potential to improve the understanding of pathologies at the vitreomacular interface and might be helpful in establishing anti-fibrotic treatment strategies.

Evaluating the ability of non-rectangular electrical pulse forms to preferentially activate nociceptive fibers by comparing perception thresholds

Abstract Aims Selective activation of nociceptive fibers is difficult using electrical stimulation as the activation threshold is higher than for non-nociceptive fibers. It remains unclear to what extent accommodation of non-nociceptive fibers during slowly rising electrical pulses can be utilized to reverse this activation order. The aim of this study was to evaluate the ability of different pulse forms to activate nociceptive fibers with minimal co-activation of non-nociceptive fibers by comparing subjective perception thresholds (PT). Methods Electrical pulses were applied on the volar forearm of 25 subjects with (1) small diameter pin electrodes providing high current density in the skin epidermis, where primarily nociceptive fibers terminate and (2) standard patch electrodes (2.63 cm2). PTs were obtained for exponential current increase, linear current increase, increasing form of exponential current decay (ED), and standard rectangular current pulses. All pulse forms were tested at two relatively long durations (5 and 50 ms). The PT ratio between patch- and pin electrode was calculated as an estimate of the ability of a pulse form to preferentially activate nociceptive fibers. The short form McGill pain questionnaire (SF-MPQ) was used to assess perceived quality of pain for all pulse forms. Results For the pin electrode, PT tended to decrease with increasing pulse area. Patch electrode PT tended to increase for increasing pulse area for non-rectangular 50 ms pulses, in contrast to 5 ms pulses, indicating accommodation of non-nociceptive fibers. Largest PT ratio was obtained for the 50 ms ED. SF-MPQ scores were higher for the pin- compared to the patch electrode. Pin electrode pain qualities were mainly described as stabbing and sharp. SF-MPQ scores did not differ between pulse forms. Conclusions Long duration ED pulses seem to activate nociceptive fibers better than regular, short duration pulses; most likely reflecting accommodation of non-nociceptive fibers.

A Dental Prosthesis from the Early Modern Age in Tuscany (Italy).

During archaeological excavation, carried out in the S. Francesco Monastery at Lucca (Tuscany, Italy), a golden dental appliance was discovered. The prosthesis was found, together with commingled human remains, in the collective tomb of the aristocratic family of the Guinigi, a powerful family who governed Lucca from 1392 until 1429. The exact archaeological dating of the prosthesis was not possible, but some elements suggest a dating to the beginning of the 17th century. Aim of the paper is to study and describe the dental appliance trough a multidisciplinary approach. Macroscopical and micro-CT examinations were performed to investigate the technics used for the realization of the dental prosthesis. SEM analysis was performed to study alloy composition of the metallic fixing lamina and microstructure of the deposits on the dental surface. The dental prosthesis consists in five mandibular teeth: three central incisors and two lateral canines linked together by a golden band inserted into the dental roots to replace the anterior arch of the jaw. Micro-CT scan revealed the presence of two small golden pins inserted into each tooth crossing the root and fixing the teeth to the internal gold band. SEM examination of the lamina indicated a homogeneous composition, with average contents of 73 wt% gold, 15.6 wt% Ag, and 11.4 wt% Cu. Apposition of dental calculus on the teeth indicated that the prosthesis had been worn for a long period. This dental prosthesis provides a unique finding of technologically advanced dentistry in this period. In fact, during the Early Modern Age, some authors described gold band technology for the replacement of missing teeth; nevertheless, no direct evidences of these devices have been brought to light up so far.

High power experimental studies of hybrid photonic band gap accelerator structures

This paper reports the first high power tests of hybrid photonic band gap (PBG) accelerator structures. Three hybrid PBG (HPBG) structures were designed, built and tested at 17.14 GHz. Each structure had a triangular lattice array with 60 inner sapphire rods and 24 outer copper rods sandwiched between copper disks. The dielectric PBG band gap map allows the unique feature of overmoded operation in a ${\mathrm{TM}}_{02}$ mode, with suppression of both lower order modes, such as the ${\mathrm{TM}}_{11}$ mode, as well as higher order modes. The use of sapphire rods, which have negligible dielectric loss, required inclusion of the dielectric birefringence in the design. The three structures were designed to sequentially reduce the peak surface electric field. Simulations showed relatively high surface fields at the triple point as well as in any gaps between components in the clamped assembly. The third structure used sapphire rods with small pin extensions at each end and obtained the highest gradient of $19\text{ }\text{ }\mathrm{MV}/\mathrm{m}$, corresponding to a surface electric field of $78\text{ }\text{ }\mathrm{MV}/\mathrm{m}$, with a breakdown probability of $5\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}1}$ per pulse per meter for a 100-ns input power pulse. Operation at a gradient above $20\text{ }\text{ }\mathrm{MV}/\mathrm{m}$ led to runaway breakdowns with extensive light emission and eventual damage. For all three structures, multipactor light emission was observed at gradients well below the breakdown threshold. This research indicated that multipactor triggered at the triple point limited the operational gradient of the hybrid structure.

Comparative studies on standard and new test methods for evaluating the effects of structural firefighting gloves on hand dexterity

This research identifies laboratory test methods designed to advance assessment of the effects of structural firefighter gloves on a firefighter’s ability to perform tasks with their hands. Two new hand dexterity test methods are discussed: a modified tool test for measuring glove effects on gross or whole hand motor control, and a novel cylinder lift method for evaluating glove effects on fine or fingertip hand dexterity. Data generated by testing a representative group of structural firefighter and other responder gloves are used to show that these new test methods provide less variable data and a more useful and informative assessment of the effects of glove construction on hand dexterity than that provided by standard small pin pegboard tests. Based on these comparisons, a combination of the newly developed tool and cylinder lift test methods are recommended for evaluating the effects of structural firefighter gloves on hand dexterity in standards used as the basis of certifying the performance of structural firefighter clothing.

The Rhetoric of Occupation

The Rhetoric of Occupation

Increased pin diameter improves torsional stability in supracondylar humerus fractures: an experimental study.

BackgroundPediatric supracondylar humerus fractures are the most common elbow fractures seen in children, and account for 16 % of all pediatric fractures. Closed reduction and percutaneous pin fixation is the current treatment technique of choice for displaced supracondylar fractures of the distal humerus in children. The purpose of this study was to determine whether pin diameter affects the torsional strength of supracondylar humerus fractures treated by closed reduction and pin fixation.MethodsPediatric sawbone humeri simulating a Gartland type III fracture were utilized. Four different pin configurations were compared. Specimens were subjected to a torsional load producing internal rotation of the distal fragment. The stability provided by 1.25- and 1.6-mm pins was compared.ResultsThe amount of torque required to produce 15° and 25° of rotation was greater using larger diameter pins in all models tested. The two lateral and one medial large pin (1.6 mm) configuration required the highest amount of torque to produce both 15° and 25° of rotation.ConclusionsIn a synthetic pediatric humerus model of supracondylar humerus fractures, larger diameter pins (1.6 mm) provided increased stability compared with small diameter pins (1.25 mm). Fixation using larger diameter pins created a stronger construct and improved the strength of fixation.

Comparison of Hybrid Metal-Composite Small-Pin Joints with Conventional Ones in Terms of Static and Fatigue Strength

The current research deals with special hybrid metal-composite joints (MCJ) which use thin sheet-metal reinforcement with small die-fixed pins (2-3 mm) embedded into the composite part of the joint. This technological trick significantly and positively influences strength of the metal-composite bolted joints loaded in out-of-plane direction. This fact was proved by comparison of pull-off static and fatigue tests results of MCJs with and without reinforcement.