Pin Diameter Research Articles

Use of a novel indentometer to evaluate skin stiffness in healthy and diseased human skin.

Mechanical behavior of the skin can be evaluated by different non-invasive methods. In this study, we applied a new measurement device based on indentometry to determine the skin mechanical properties in healthy individuals and in patients with systemic sclerosis (SSc). Three studies were performed. Study 1 included 100 healthy individuals (46 male and 54 female) divided into four age groups with mean ages of 21.5, 28.9, 51.2, and 69.3 years, respectively. Test sites were located on the center of the forehead and the middle of both volar forearms. Study 2 included 16 healthy individuals (two males and 14 females). Test sites were on both volar forearms. Measurements were made before and after the application of Vaseline and emulsion with 12% urea. Study 3 included 20 patients (one male and 19 females) with SSc and 60 age-matched healthy individuals (23 males and 37 females). Test sites were on the center of the forehead and the middle of both volar forearms. Skin stiffness was measured with skin Indentometer IDM 800 (Courage + Khazaka, Cologne, Germany) equipped with two probes with pin diameters of 3 and 5mm, respectively. The stiffer the skin, the less deep the displacement by the indenter. The smaller the diameter, the deeper the pin will go into the skin when using the same force. In addition, the Corneometer CM 820 (Courage + Khazaka) was used to determine epidermal water content in study 2. Indentometric (IDM) values of healthy subjects measured with both probes were lower on the forehead compared to volar forearms. There was no significant difference between both forearms. In all age groups, the IDM values on the male forearms were lower than on the female forearms whereas there was no significant difference on the forehead. In both sex and on all test locations a significant positive correlation between age and IDM values measured with both probes was observed. There was a significant positive correlation between IDM values measured with both probes. The application of moisturizers induced significant changes in epidermal water content whereas the IDM values remained unchanged. At both the forehead and volar forearms, the IDM values in patients with SSc were significantly lower compared to the healthy control skin. The non-invasive indentometric method used can successfully distinguish the changes in normal skin mechanical properties related to age, sex, and anatomical location, as well as in patients with SSc. The method is not appropriate to study the changes related to epidermal hydration.

Pin-bearing mechanical behaviour of composites fabricated via fused filament fabrication as a function of reinforcing, pin diameter and W/D ratio

Additive manufacturing is an advanced technology able to produce parts with different grades of complexity, including its shape, microstructure, functionality and material. Regarding material complexity nowadays, it is possible to produce polymer parts with customized reinforced fibre filling such as carbon, Kevlar or glass. However, their mechanical behaviour is still under investigation and no data are available on the bearing strength for additively manufactured composites. The aim of this work is to provide a contribution on this topic to ensure safe joint design with the current and innovative technologies. In this article the authors present the experimental characterization of polymer filled with Kevlar to pin bearing test. Samples have been designed as a function of filling and geometry parameters. Results have been analysed with statistical methods. Finding highlight similar and different behaviour regarding samples produced with conventional process. The most interesting result is that the authors demonstrate how the pin diameter is significant for the results, particularly for the stiffness keeping constant the bearing strength.

Mechanical Testing of Connections Blind Bolted to the Thick Glass-Fiber-Reinforced Polymer Spar Cap of a Decommissioned GE37 Wind Turbine Blade

Millions of tons of glass-fiber-reinforced polymer (GFRP) composite wind turbine blades are expected to age out of service over the next 30 years. Research is being conducted on repurposing these structures as new civil infrastructure products. The GFRP material in these decommissioned wind blades has been shown to retain significant strength and stiffness for second-life applications. However, for repurposing as new products, they will need to be connected to other structural members. The connections employed for this need to be designed, evaluated, and tested prior to their use. Here, we present the results of detailed testing of bolted connections for load-carrying appurtenances that will carry the phases and shield wires (e.g., insulators, crossarms, davits, guy wires, posts) to the spar cap of an 11-year-old 1.5 MW GE37 wind blade, intended for use as a repurposed transmission pole (i.e., a BladePole). Details of ASTM-type pull-out and bearing capacity tests using different types of blind bolts, and tests of a full-scale steel bracket connection called a “universal connector,” are reported. The effects of the different blind bolts, pin diameters, and loading directions relative to the composite laminate structure (longitudinal or transverse) for both the coupon- and full-scale connector bracket tests are described. The ability to design and construct robust connections for repurposed wind blade structures was demonstrated.

Contact reliability modeling and assessment of electrical connectors with multi-aperture slotted leaf spring contacts

Multi-aperture electrical connectors are widely used in the aerospace system to provide high-reliability and high-quality connections. The existing reliability assessment methods only focus on the single-aperture electrical connectors, and ignored the influence of the aperture difference on the reliability of electrical connectors, which may lead to errors in the evaluation results. In order to assess the contact reliability of multi-aperture electrical connectors at storage environment, this paper build a mathematical relationship between structure parameter of contact pairs and contact force by analyzing the slotted leaf spring jack reed structure of the contact pair and using the cantilever beam model. Based on the growth law of the oxide layer on the surface of the contact pair, the degradation trajectory model of the contact pair performance was set up which incorporating the structure parameters of contact pairs, such as pin diameter, reed length, radius of curvature of the inner and outer surfaces, and the acceleration model was established by combining the Arrhenius equation. Then based on the established degradation trajectory model, the degradation failure distribution model of contact pairs was derived, and the contact reliability evaluation model of multi-aperture electrical connectors was established by using the weakest ring model. The test scheme of constant stress accelerated degradation of electrical connectors was formulated and carried out. Finally, this paper verified the correctness of the model through analyzing the test data, and obtained the reliable life of multi-aperture electrical connectors under the storage environment temperature, which realized the contact reliability assessment of multi-aperture electrical connectors.

The Effect of Reeds and Washed Rice Water on The Growth and Production of White Oyster Mushroom (Pleurotus Ostreatus)

This study aims to determine the effect of reeds as a planting medium and washed rice water on the growth and production of white oyster mushroom. The research was conducted in April-July 2021 in Polopadang, Kapala Pitu District, North Toraja Regency.The research was carried out in the form of a factorial experiment with 2 different factors arranged in a randomized block design (RBD), namely: As the treatment used Imperata and washed rice water. Imperata (reeds) as 1st factor consists of three treatment levels, namely R0 = control, R1 = 10% Reeds, R2 = 20% reeds, while washed rice water as 2nd factor consists of five treatment levels, namely W0 = control, W1 = 10 ml of washed rice water, W2 = 20 ml of washed rice water, W3 = 30 washed rice water, W4 = 40 ml of washed rice water. The results showed that the treatment of 10% Imperata (L1) and 10 ml water leri (L2) gave the best results on the growth and production of white oyster mushrooms in this case, namely: number of mushroom pin head, fresh fruit body weight, and mushroom diameter. Number of pin head and diameter of mushroom hood have a positive and significant correlation to weight of mushroom, each with a correlation coefficient 0.799 and 0.807. This research implies that the use of reeds and rice washing water in the cultivation of white oyster mushrooms has promising potential. This combination can promote mold growth, reduce production costs, and contribute to financial sustainability.

An algorithm for automatically establishing a multi- parameter RVE model for z-pin composite laminates

Z-pinning is an effective method to improve the delamination resistance of composite laminates. The microstructure and manufacturing parameters have a great influence on the properties of z-pin composite laminates. In order to explore the influence of microscopic characteristic parameters on material properties and damage analysis, a parameterized RVE finite element model algorithm for automatic establishment of z-pin reinforced composites was proposed. The algorithm involves avoiding in-plane fibers to pin, generating fiber waviness, and assembling pin-fiber–matrix. Moreover, the statistical distribution of fiber misalignment angle can also be controlled. The developed program can generate RVE models with different parameters efficiently and quickly, such as fiber volume fraction, pin volume fraction, pin diameter, RVE size and fiber waviness. The statistical verification of the distribution of fiber misalignment angle can satisfy the probability distribution modeling of fiber angle. The generated model is divided into meshes, and finite element calculation can be realized. This work is of great significance to study the effects of microscopic characteristics on the properties and to optimize the design of z-pin reinforced composites.

Design & Optimization Gudgeon Pin for C.I. Engine

Abstract: Premature wear of the Gudgeon pin is the major concern for the company. Gudgeon pin connects the piston and the small end of the connecting rod of IC engines. This paper deals with Stress analysis and Fatigue analysis of Gudgeon pin used in diesel engine. In stress analysis frictional stresses and von-Mises stresses coming on Pin are determined using finite element analysis tool ANSYS 16. Effect of different factors on frictional stresses and Von-Mises stresses such as change in internal diameter of pin and application of diamond-like carbon (DLC) coating are analyzed. In Fatigue analysis, fatigue life of Pin is determined using fatigue analysis tool FEMFAT 5.0 b. Effect of change in surface roughness of connecting rod small end bush and change in internal diameter of pin on fatigue life is analyzed.

A comprehensive investigation on the effect of controlling parameters of ultrasonic peening treatment on residual stress and surface roughness: Experiments, numerical simulations and optimization

This paper aims to study the effect of controlling parameters of ultrasonic peening treatment (UPT), including the pin diameter, the vertical velocity of the pin, friction coefficient etc. on the residual stress, PEEQ and surface roughness. A method was promoted to simulate the UPT process using the ability of the ABAQUS scripting interface and transferring results between ABAQUS analyses. The finite element results of the proposed method were consistent with the UPT simulation. Moreover, the finite element results agreed well with experimental measurements of residual stress, surface roughness and surface deformation. The results revealed that increasing the pin diameter, the vertical velocity of the pin and also the number of impingements increased the depth of the compressive residual stress layer. Decreasing the vertical and horizontal velocity of the pin and increasing the pin diameter and the distance between two adjacent impingements resulted in a decline of surface roughness parameters (Ra and Rq). A combination of finite element model and multi-objective optimization technique was implemented to determine the optimum controlling parameters of UPT for reaching the maximum compressive residual stress and the minimum surface roughness. For the optimum proposed controlling UPT parameters, the values of −386 MPa, 16.7 μm and 20.9 μm were obtained for the surface residual stress, Ra and Rq, respectively.

Biomechanical comparison of one pin versus two pin fixation in a canine tibial tuberosity avulsion fracture model.

To determine whether one larger or two smaller diameter pins used for tibial tuberosity avulsion fracture (TTAF) stabilization provides greater axial tensile strength and stiffness when subjected to monotonic mechanical load to failure in normal skeletally mature canine cadavers. Paired ex vivo biomechanical study. Eleven pairs of adult cadaveric dog tibias. Twenty-two tibias from 11 dogs were collected to model a TTAF. Each limb of a pair was randomly assigned a one or two-pin fixation. Tibias were subjected to monotonic, axial load to failure. Fixation stiffness, strength, and pin insertion angles were analyzed with parametric testing. Significance was set at p < .05. The mean strength of the single-pin fixation was 426.2 ± 50.5 N compared to two-pin fixation at 639.2 ± 173.5 N (p = .003). The mean stiffness of the single-pin fixation was 57.3 ± 18.7 N/mm and the two-pin fixation was 71.7 ± 20.5 N/mm (p = .029). The normalized ratio between one and two-pin fixation had a mean stiffness of 68% ± 25.8% and strength of 82.8% ± 24.6%. In an ex vivo cadaveric TTAF model, vertically aligned two-pin fixation offers greater strength and stiffness when compared to a single-pin fixation. When repairing TTAF, surgeons should aim to apply two vertically aligned pins rather than a single pin for greater strength and stiffness.

Fiber orientation in continuous fiber-reinforced thermoplastics/metal hybrid joining via multi-pin arrays

Abstract Continuous fiber-reinforced thermoplastics (CFRTs) can in combination with high-strength metals offer characteristics that cannot be achieved with mono-material parts. One possible example is the combination of locally high-temperature resistance in the metal component with superior weight-related mechanical properties due to the CFRT component. This approach requires a reliable and durable joining technology, which considers the material-specific properties and allows to exploit the full potential of CFRT/metal hybrid parts. A promising approach in the field of CFRT/metal joining is the use of metallic pins, which can be embedded in the locally heated CFRT component to create a form-fitting joint. In the current state of the art, primarily single-pins are investigated and characterized: especially the distinct fiber orientation in the direct pin pressing process is only described for single-pin joints. Behind this background, the present study aims at creating an understanding of the fiber orientation mechanism for multi-pin arrays. Therefore, in the scope of this study, unidirectional reinforced glass fiber/polypropylene samples are joined via direct pin pressing and infrared heating with different 1D and 2D multi-pins arrays with different pin-diameters, spacing and pin distributions. The resulting joint morphology is consequently analyzed using micro-computer-tomography. Based on the performed investigations, a model for the fiber displacement mechanism is proposed, and the first recommendations for the design of fiber-friendly multi-pin joints with unidirectional reinforcements are given. It showed that especially pin-spacing in fiber orientation in dependency of the pin diameter is critical for a fully reconsolidated joint quality, and it is suggested that a pin-offset in the fiber direction is beneficial for a fiber-friendly joining process.

Material flow and channel geometry evolution during friction stir channeling process – Impact of tool geometry and process parameters

The capability of manufacturing controlled and uniform geometry of channels is critical for potential application of friction stir channeling in thermal systems. The channel geometry is governed by the material flow around the tool during the channeling process. The heat generation and material flow are closely dependent on the friction stir channeling parameters (tool geometry and process parameters). In the present investigation the interrelation between the friction stir channeling parameters with material flow and channel geometry is analysed. The channel geometry is found to be function of tool geometry for constant process parameters. The channel area and height increase with reduction in the pin diameter, the shoulder diameter and with increase in the pin length. The process parameters govern the channel geometry for constant tool geometry. The increase in tool rotation speed, and reduction in tool travel speed and shoulder clearance resulted in reduction in channel area and height.

Process parameters for friction stir welding on A319 aluminium alloy using hybrid technique for order of preference by similarity to an ideal solution and grey relational analysis multi-criteria decision-making method

The major goal of this study is to look into friction stir welding process parameter optimization with the combined decision model, the tensile strength of the best parameter combinations is higher. The recommended hybrid strategy for order preference by similarity to ideal solution (technique for order of preference by similarity to an ideal solution) and grey relational analysis method are used to discover the optimum process parameters. It is also suitable for welding aluminium alloy A319 is Tool rotational speed (r/min), Feed for welding (mm/min), and diameter of tool pin (mm) are all considered while using the friction stir welding process. This operation is primarily implemented through various experiments using Taguchi L9 orthogonal arrays. To this problem, the (technique for order of preference by similarity to an ideal solution) and (grey relational analysis) models are used. Hence, this technique has demonstrated the technology used to identify multi-criteria decision-making in friction stir welding and process parameter optimization for the best results.

Miniaturization of Non-Assembly Metallic Pin-Joints by LPBF-Based Additive Manufacturing as Perfect Pivots for Pantographic Metamaterials.

This work introduced additively manufactured non-assembly, miniaturized pin-joints for pantographic metamaterials as perfect pivots. The titanium alloy Ti6Al4V was utilized with laser powder bed fusion technology. The pin-joints were produced using optimized process parameters required for manufacturing miniaturized joints, and they were printed at a particular angle to the build platform. Additionally, this process optimization will eliminate the requirement to geometrically compensate the computer-aided design model, allowing for even further miniaturization. In this work, pin-joint lattice structures known as pantographic metamaterials were taken into consideration. The mechanical behavior of the metamaterial was characterized by bias extension tests and cyclic fatigue experiments, showing superior levels of performance (no sign of fatigue for 100 cycles of an elongation of approximately 20%) in comparison to classic pantographic metamaterials made with rigid pivots. The individual pin-joints, with a pin diameter of 350 to 670 µm, were analyzed using computed tomography scans, indicating that the mechanism of the rotational joint functions well even though the clearance of 115 to 132 µm between the moving parts is comparable to the nominal spatial resolution of the printing process. Our findings emphasize new possibilities to develop novel mechanical metamaterials with actual moving joints on a small scale. The results will also support stiffness-optimized metamaterials with variable-resistance torque for non-assembly pin-joints in the future.

Evaluation of End-threaded Positive and Negative Profile Intramedullary Pins for Management of Long Bone Fractures in Dogs

Background: Intramedullary pinning (IMP) is the most commonly used internal skeletal fixation technique. Threaded pins (also called Schanz Screws) provide a comparatively better holding strength than non-threaded tipped intramedullary pins. The present study was planned to evaluate and compare the efficacy of positive and negative profile end threaded intramedullary pins in the management of long bone fractures in dogs. Methods: Eleven clients owned dog suffering from fracture of long bones were randomly divided in to two groups. Animals of group I (n=5) and group II (n=6) were treated with end threaded positive and negative profile intra medullary pin, respectively. The intramedullary pinning was done using 3 to 5.5 mm diameter pins under general anesthesia, the time taken for surgery, size of end threaded intramedullary pin used in each case was noted down. Radiographs were taken preoperatively, immediately after fixation and then at regular intervals till signs of radiographic healing were evident. Result: There was no significant difference between the two groups in terms of time taken for fixation/surgery and in healing time, with a gradual improvement in weight bearing postoperatively in both the groups. There was mild periosteal callus formation in all the cases when observed radiographically and the pins were removed after radiographic healing was evident in an anticlockwise manner using Jacob’s chuck and key, under mild sedation. There was no complication like implant failure or pin tract sepsis or pin migration or pin breakage in any of the cases of two groups. However, passing the positive profile end threaded intramedullary pin in distal fragment is comparatively smoother and easier as compared to negative profile end threaded intra medullary pin.

Multi-Objective Modified Differential Evolution Methods for the Optimal Parameters of Aluminum Friction Stir Welding Processes of AA6061-T6 and AA5083-H112

This study introduces a modified differential evolution approach (MoDE) for evaluating the optimal objective and parameter values of the friction stir welding (FSW) process of dissimilar materials: AA5083 and AA6061. The aim of this study is to investigate the ultimate (UTS), maximum hardness (MH), and minimum heat input (HI) of the weld zone. The controlled welding parameters were shoulder diameter, rotation speed, welding speed, tilt angle, pin type, reinforcement particle type, and tool pin movement direction. The D-optimal experimental design method was used to create the experiment and obtain the mathematical model for optimizing the targeted objectives. The optimal rotational speed, welding speed, shoulder diameter, tilt angle, pin-type, additive type, and tool pin movement are 1162.81 rpm, 52.73 mm/min, 21.17 mm, 2.37 degrees, straight cylindrical, silicon carbide, and straight movement direction, respectively. The optimal values for UTS, MH, and HI are 264.68 MPa, 105.56 HV, and 415.26 °C, respectively. The MoDE outcome exceeded particle swarm optimization (PSO), the original differential evolution algorithm (DE), and the D-optimal design (experiment) results. The MoDE provides better UTS, MH, and HI than other approaches by an average of 8.04%, 4.44%, and 2.44%, respectively. In particular, when comparing results produced by using various approaches, we discovered that the MoDE results are 7.45%, 4.45%, and 3.50% better than PSO, DE, and the experimental results, respectively. All methods were evaluated for their reliability by comparing the results of actual experiments to those predicted by theory, and we discovered that the MoDE yielded the smallest percentage difference between the two, at 1.49%, while PSO and DE yielded differences of 5.19% and 3.71%, respectively.

Experimental and Numerical Investigation on Effects of Pin Diameter on Multi-Point Forming

Multi-point forming (MPF) is an advanced and flexible method to form sheet metal workpieces. Although there are studies investigating different aspects of this method, the studies on the effects of pin diameter on sheet and pin contact on MPF are insufficient. In this study, pins with diameters of 10, 12, and 14 mm were used to investigate the damage factor, effective stress distribution, and required forming loads of three forms of aluminum 1100 parts in finite element simulations. In addition, experimental works were conducted for the 12 mm pin and the forming loads and the thinning on the contact points of pin and formed sheet metal parts were compared with the simulations. The 14 mm pin forming provided the highest effective stress distributions and the damage factors of 0.448, 0.770, and 0.329 were obtained for form1, form2, and form3, respectively. The percentage errors between experimental works and simulations using 12 mm pin forming were calculated as 7.4, 5.1, and 2.4% for all forms 1 to 3. In conclusion, pin diameter was shown to have significant effects on the MPF process. Larger diameter pins resulted in higher loads and tearing of sheet metal.

Multiparametric experimental analysis of the pin disc rotational cavitation generator

The alarming increase in water pollution is driving research into novel, environmentally friendly treatment solutions such as hydrodynamic cavitation. This study is part of the research on the pin disc rotational generator of hydrodynamic cavitation, which utilises the low pressure wake behind the rotor pins to induce cavitation and the short gap between the rotor and stator pins to enhance cavitation cloud fluctuation. Due to the lack of understanding of the effects of cavitation treatment, a laboratory device was built to investigate the mechanisms of cavitation generation and the effects of various geometric features such as the diameter, number, and shape of the rotor pins and the gap size between the rotor and stator pins. Using simultaneously measured pressure fluctuations and high-speed visualisation, a method was developed to quantify the extent of cavitation, and it was found that throttling the high-pressure side had an order- of- magnitude smaller effect on cavitation than the number of rotor pins. It was found that a smaller number of rotor pins with large downstream area produced the most aggressive cavitation conditions. The weak spectral response and lower mean vapour cloud area, as well as the lower fluctuation in the case without stator, demonstrated the key role of the stator in the onset and aggressiveness of cavitation.

A comparison of pin site complications between large and small pin diameters in robotic-assisted total knee arthroplasty

PurposeRobotic-assisted total knee arthroplasty typically necessitates use of tracking pins, which can vary in diameter. Complications such as infections and fractures at the pin-site have been observed, but clarification of the effect of pin diameter on complication is needed. The aim of this study is to compare the pin-related complication rates following robotic-assisted total knee arthroplasty between 4.5 mm and 3.2 mm diameter pins.MethodsIn this retrospective cohort study, 90-day pin-site complication rates after robotic-assisted total knee arthroplasty were compared between 4.5 mm diameter and 3.2 mm diameter groups. In total, 367 patients were included: 177 with large pin diameter and 190 with small pin diameter. All four pin sites were evaluated using postoperative radiographs. Cases without orthogonal views or visualization of all four pin tracts were noted. Multivariate logistic regression was used to control for age, which differed between the two cohorts.ResultsThe rate of pin-site complications was 5.6% in the large pin diameter cohort and 2.6% in the small pin diameter cohort, with no statistically significant difference between the groups. The adjusted odds ratio for complications in small compared to large diameter group was 0.48, with a p-value of 0.18. The most common pin-site complication was infection/persistent drainage, found in 1.9% of patients, followed by intraoperative fracture of the second cortex in 1.4%. Intraoperative fracture could not be ruled out in 96 cases due to inadequate radiographic visualization of all pin sites. There was one postoperative pin-site fracture in the large diameter cohort, which required operative fixation.ConclusionThis study demonstrates no statistically significant difference in pin-site complication rates after robotic-assisted total knee arthroplasty between 4.5 mm and 3.2 mm pin diameter cohorts, although there was a trend towards increased intraoperative and postoperative pin-site fractures in the 4.5 mm group.

Mathematical and experimental examination of the effect of the stepped pin tool profile on the characterization of AA 6061-T6 underwater friction stir welding

This research paper presents the mathematical model to design a stepped pin profile tool and its durability index. A mathematical model is being developed by considering tools that should generate the same heat as conventional conical tools and stepped tools by varying the shoulder to pin diameter ratio (D/d). Aluminum alloy AA6061-T6 with a thickness of 6 mm fabricated using a butt-type weld configuration and newly developed conical stepped pin profile tools with water as a cooling medium. The result shows that a conical stepped tool shows better mechanical properties of the welded joints compared with a conventional conical tool. When compared to other stepped conical pin profile tools, one with a (D/d) of 3 has superior mechanical and microstructural properties and as the D/d ratio increases, the tool pin durability index falls.

Optimization of Pin Position and Angle for Z-Pin-Reinforced Foam Core Sandwich Structures

Sandwich panels (SP) are very promising components for structures as they ally high levels of specific stiffness and strength. Civil, marine and automotive industries are some examples of the sectors that use SPs frequently. This work demonstrates the potential of manufacturing Z-pin-reinforced foam core SPs, using a design strategy that indicated optimal values for both pin position and angle, keeping the same pin diameter as determined in a previous study. A simple search algorithm was applied to optimize each design, ensuring maximum flexural stiffness. Designs using optimal pin position, optimal pin angle and optimal values for both parameters are herein investigated using numerical and experimental approaches. The optimal pin position yielded an increase in flexural stiffness of around 8.0% when compared to the non-optimized design. In this same comparison, the optimal pin angle by itself increased the flexural stiffness by about 63.0%. Besides, the highest increase in the maximum load was found for those composites, molded with optimized levels of pin position and pin angle, which synergistically contributed to this result. All results were demonstrated with numerical and experimental results and there was a good agreement between them.