Lining Materials Research Articles

Thermal Differences in the Plantar Surface Skin of the Foot after Using Three Different Lining Materials for Plantar Orthotics.

The lining materials of plantar orthoses are chosen for their hardness, breathability, and moisture absorption, but without there being any clear scientific criterion. Thermographic analysis would provide information about the thermal response of the sole of the foot, and would thereby allow the choice to be adapted in accordance with this criterion. The objective of this study was to evaluate plantar temperatures after the use of three materials with different characteristics. Plantar temperatures were analyzed by using a FLIR E60BX thermographic camera on 36 participants (15 men and 21 women, 24.6 ± 8.2 years old, 67.1 ± 13.6 kg, and 1.7 ± 0.09 m). Measurements were made before and after (3 h) the use of three lining materials for plantar orthoses (Material 1: PE copolymer; Material 2: EVA; Material 3: PE-EVA copolymer) on different days. For Material 1 (PE), the temperature under the heel was significantly higher after exercise, increasing from 30.8 ± 2.9 °C to 31.9 ± 2.8 °C (p = 0.008), and negative correlations were found between room temperature and the pre/post temperature difference for the big toe (r = -0.342, p = 0.041) and the 1st metatarsal head (r = -0.334, p = 0.046). No significant pre/post temperature differences were found with the other materials. The three materials thermoregulated the plantar surface efficiently by maintaining the skin temperature at levels similar to those evaluated before exercise. If PE is used as a lining material, it should be avoided for the heel area in patients with hyperhidrosis or those with a tendency to suffer from skin pathologies due to excess moisture.

Peningkatan Kemandirian Belajar Matematika Materi Konsep Segi Empat Dan Segitiga Dengan Metode RBL Pada Siswa SMPN 91

This research examines the learning model of Resource Based Learning is not something new for teachers at all. The Resource Based Learning learning model prioritizes cooperation in solving problems to apply knowledge and skills in order to achieve learning objectives. The research setting was at SMP Negeri 91 East Jakarta with 36 class VII-C students as subjects. The research was conducted for 2 cycles. With 3 meetings each cycle. The conclusions obtained from this study are that when referring to the results of initial observations before using the Resource Based Learning method, it was found that only 27.72% of students could have the ability to work on row and row material well. After the research was carried out by giving the Resource Based Learning method, in cycle 1 there was an increase of 72.22% at the end of the cycle students were able to work on series and line material, then in cycle 2 as many as 94.66% of students were able to work on series and line material and found increased learning outcomes in mathematics due to the Resource Based Learning method.

Similar model test of a mudstone-interbedded–sandstone-bedding rock tunnel

Herein, for the Zhengzhou–Wanzhou high-speed railway mudstone-interbedded–sandstone-bedding rock tunnel, the mechanical parameters of the surrounding rock were tested via uniaxial and triaxial compression tests, and these were converted into rock mass parameters according to the Hoke–Brown theory. Various similar mudstone, sandstone, and tunnel lining materials were prepared in accordance with the similarity theory and orthogonal tests. Based on a similar model test, the effects of the bedding structure and different burial depths on the tunnel lining were simulated. The displacement and contact pressure along the normal direction of the tunnel bedding were evidently greater than those along the tangential direction of the surrounding rock. Further, increasing the burial depth of the bedding tunnel first resulted in longitudinal cracking at the lining invert. Simultaneously, floor heaving occurred in the lining invert, and longitudinal cracks appeared at the lining arch waist corresponding to the normal position of the bedding structure. The similar model test results were found to be in good agreement with the tunnel field test results, indicating that the test model could simulate the mechanical behaviour of bedding rock mass tunnels.

Tensile Bond Strength between Different Denture Base Materials and Soft Denture Liners.

(1) Background: Various materials are available for CAD-CAM denture base fabrication, for both additive and subtractive manufacturing. However, little has been reported on bond strength to soft denture liners. Therefore, the aim of this study was to investigate tensile bond strength, comparing between different denture base materials and soft denture liners. (2) Methods: Seven different materials were used for denture base fabrication: one heat-polymerized polymethyl methacrylate, three materials for subtractive manufacturing, two materials for additive manufacturing and one polyamide. Two materials were used for soft denture lining: one silicone-based and one acrylate-based. The study was conducted according to the specification ISO No. 10139-2:2016, and the type of failure was determined. The Kruskal-Wallis test with Dunn's post hoc test was used to analyse the values of tensile bond strength, and Fisher's exact test was used to analyse the type of failure. p Values < 0.05 were considered statistically significant. (3) Results: The tensile bond strength values were not statistically significantly different combining all the materials used for denture base fabrication with the acrylate-based soft denture liner (p > 0.05), and the average values ranged between 0.19 and 0.25 Mpa. The tensile bond strength values of the different denture base materials and silicone-based denture liner were statistically significantly different (p < 0.05), and the average values ranged between 1.49 and 3.07 Mpa. The type of failure was predominantly adhesive between polyamide and both additive-manufactured denture base materials in combination with the acrylate-based soft liner (p < 0.05). (4) Conclusions: The use of digital technologies in denture base fabrication can have an influence on different tensile bond strength values for soft denture liners, with different types of failure when compared with heat-cured PMMA. Similar tensile bond strength values were found between the acrylate-based soft denture liner and denture base materials. Significant differences in tensile bond strength values were found between the silicone-based soft denture liner and denture base materials, where the additive-manufactured and polyamide denture base materials showed lower values than heat-cured PMMA and subtractive-manufactured denture base materials.

Control of friction hoist head rope tensions revisited

ABSTRACT Matching of head ropes and drum grooves in multi-rope friction winding systems is essential for effective load sharing between the winding ropes. Analytical methods were developed in the 1960s to evaluate rope load disparity when rope groove depths are mismatched. Although this historical analysis ignored flexibility in rope groove lining materials, it is widely accepted that rope groove flexibility has the effect of reducing the disparity in load sharing. This paper recounts the original 1960s work in which rope load disparity was analyzed to provide rope groove depth tolerances of rigid grooves and provides a new rope groove depth tolerance for flexible grooves. Both rigid and flexible groove analyses show the importance of an adequate distance between the conveyance at its uppermost normal position in the shaft and the head ropes’ tangent point on the hoist drum. They also show that ground-mounted hoists are more tolerant to groove depth mismatch. Maintenance methods, including the collar-to-collar test, are revisited to reflect this latest analysis.

Parametric Effects on the Coefficient of Friction of a Novel Composite Material for Automobile Brake Linning

Brake lining, a friction lining material has over the years been produced mainly from asbestos. Asbestos health hazards have necessitated the need to source friction lining materials from other safer directions. A novel composite from local materials was developed. The brake lining production was a dispersion hardening process by the techniques of powder metallurgy of finely divided particles of the raw material powder mix. The raw materials included sawdust, resin, rubber latex, clay, carbon black, brass chips, zinc oxide and sulphur. The friction lining material thus produced, with its friction coefficient was analysed relative to its responses to increasing temperatures and pressures. The environment of increasing temperatures and pressures is its operating condition, in situ. Temperature range studied was from 300C-3000C, while pressure range was from 50KPa-250KPa. Results of the analysis showed the fiction coefficient not adversely affected, with minimum value at 0.31 and maximum value at 0.56.

Hydrogen diffusion in zirconium cladding alloys with an inner liner as quantified by neutron radiography and nanoindentation

Embrittlement caused by hydride precipitates in zirconium claddings constitutes a significant risk factor for the integrity of spent nuclear fuel rods, especially during the handling and transport operations necessary before and after long-term intermediate dry storage. Zircaloy-2 is the most commonly used alloy for cladding tubes in boiling water reactors. It is typically manufactured with an inner liner to better cope with issues related to pellet-cladding interaction. Previous work showed that in clad samples possessing a liner, a significant portion of hydrogen tends to migrate towards the liner region during cool-down. In this work, the hydrogen precipitation and distribution after thermal exposures comparable to service was investigated in different commercial claddings for boiling water reactors. The resulting hydrogen distribution was quantified by means of high-resolution neutron imaging at the SINQ spallation neutron source at Paul Scherrer Institut in Switzerland, and the presence of hydrides was subsequently confirmed by metallography and nanoindentation mapping of selected samples. The results show that when a cooling rate of 30 °C/h is applied, the vast majority of the hydrogen tends to accumulate at the liner/substrate interface when a liner is present. At lower cooling rates, the hydrogen tends to distribute more homogenously into the liner material, and the cladding bulk material is left completely hydrogen-free. Neutron radiography of samples after water quenching from homogenization temperatures between 370 °C and 460 °C revealed a significant amount of hydrogen trapped in the hydrides form at the liner/substrate interface at temperatures up to 400 °C. Undissolved hydrides may act as nucleation seeds for hydrides upon cooling, contributing to the observed hydrogen segregation. A model that takes into account the interfacial properties of the region between the liner and the bulk material is proposed.

Production of galactan phthalates derivatives extracted from Gracilaria birdie: Characterization, cytotoxic and antioxidant profile

The present work explores the esterification reaction in the polysaccharide extracted from the seaweed Gracilaria birdiae and investigates its antioxidant potential. The reaction process was conducted with phthalic anhydride at different reaction times (10, 20 and 30 min), using a molar ratio of 1:2 (polymer: phthalic anhydride). Derivatives were characterized by FTIR, TGA, DSC and XRD. The biological properties of derivatives were investigated by assays of cytotoxicity and antioxidant activity (2,2-diphenyl-1-picrylhydroxyl - DPPH and 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt - ABTS). The results obtained by FT-IR confirmed the chemical modification, there was a reduction related to the presence of carbonyl and hydroxyl groups when compared to the in nature polysaccharide spectrum. TGA analysis showed a change in the thermal behavior of the modified materials. X-ray diffraction, it was shown that the in nature polysaccharide appeared as an amorphous material, while the material obtained after the chemical modification process had increased crystallinity, due to the introduction of phthalate groups. For the biological assays, it was observed that the phthalate derivative was more selective than the unmodified material for the murine metastatic melanoma tumor cell line (B16F10), revealing a good antioxidant profile for DPPH and ABTS radicals.

Research of influence of different shaped charge liner materials on penetration depth using numerical simulations

Research of influence of different shaped charge liner materials on penetration depth using numerical simulations

Influence of liner structure on EFP formation and penetration performance of a Ta-Zr liner

In order to study the formation and penetration performance of reactive liner, in this paper, a Ta-Zr alloy is used as the liner material, and large cone angle liner, spherical liner and arc-cone liner are simulated and analyzed by using AUTODYN software. The following conclusions are obtained: (1) The EFP formed by large cone angle liner has good flight stability, followed by arc cone liner; (2) The length diameter ratio of spherical shaped charge liner is larger than that of arc cone shaped charge liner; (3) The EFP penetration depth of the arc cone shaped liner is larger, and the EFP incident aperture of the large cone angle shaped liner is larger.

Simulation Study on Jet Formation and Penetration Capability of Double-layer Cylinder-cone Shaped Charges with Different Outer Liner Materials

In order to discuss the effect of different outer liner material on the performance of the double cylinder-cone shaped charge, the nonlinear dynamics software Autodyn-2D was used to carry out numerical simulation, and the jet shape and penetration of steel target were analysed when copper, nickel, tungsten, tantalum and steel were used as outer liner materials and copper was used as inner cover material. The result shows that the jet head is formed by the cylindrical part of the inner liner, and all the outer liner forms a slug. The total length of the projectile is the longest when the outer liner material is copper. The jet head velocities are the biggest when the outer liner materials are nickel and steel 4340. The shaped charge with copper outer liner yields much longer depths.

Density distribution characteristics of the explosively formed reactive material jet

The density evolution behaviour and distribution characteristics of the explosively formed reactive material jet were studied based on the SPH algorithm. Numerical simulations show that the reactive material jet has obvious expansion phenomenon under the shaped charge effect. Especially, the expansion and divergence of the jet head are obvious. In general, the density deficit occurs in the whole reactive material jet, and the density increases from the jet head to the tail. Compared with the initial density of the reactive liner material, the density of jet head decreases by about 30%. In addition, the effect laws of the reactive liner thickness, the liner cone angle, and the type of explosive on the jet density distribution were investigated. With increasing of the reactive liner thickness, increasing of the liner cone angle, and decreasing of the explosive detonation pressure, the proportion of the high-density area on the reactive jet and the average density of the jet head increase.

Damage performance of a shaped charge liner fabricated from Ti-29Nb-13Ta-4.6Zr alloy

The change of the liner material directly affects the penetration and damage performance of the shaped charge. In this paper, Ti-29Nb-13Ta-4.6Zr (TNTZ) was used as the charge liner. Autodyn software was used to analyze the jet formation of TNTZ liner, then static explosion test was conducted to analyze the penetration and damage performance of charge liners. The following conclusions were obtained: A charge liner structure was proposed for TNTZ alloy, the simulation shows that a jet with acceptable L/D ratio was formed, and the jet head velocity was around 6000 m/s. The TNTZ charge liner successfully ignited fuel tank after penetrating steel target due to chemical reaction. For the tests on C35 concrete targets, the TNTZ liner has horizontal damage effect which leads to penetration tunnel with large diameter, however the penetration depth is smaller compared to Cu liner. Such behavior makes TNTZ liner a good candidate as forward shaped charge of tandem warheads.

Orthogonal Structure Design of the Linear Shaped Charge Based on Steady-State Velocity Model

The velocity of the linear jet beams/slugs are one of the key factors affecting the penetration performance of the linear shaped charge (LSC). In order to obtain the velocity of the linear jet beams/slugs, we build the steady-state velocity model of the LSC first. Subsequent the LSC structures are designed by the orthogonal method based on the key factors of the LSC velocity model including the liner material, thickness, vertex angle, charge shape, explosive density, etc. The shape and velocity of the linear jet beams after the charge explosion are obtained by numerical simulation. Furthermore, X-ray tests are carried out to verify the simulation results. The average error of theoretical value, simulation and experimental result is less than 6%. The velocity model of the linear jet beams/slugs can guide the structural design of the LSC and play an important role in improving the penetration performance.

Bonding phase formation in eco-friendly periclase−spinel−Al bricks used in RH degassing process

Mere unburnt periclase–spinel–Al bricks have been accepted by steel mills in the chromium-free campaign of the lining materials for Ruhrstahl ̶ Heraeus (RH) degassers, in terms of comparable/optimistic performance to traditional material, low carbon emission due to unburnt manufacturing process and chromium-free material for eco-friendly steel-making process. Investigations are made on the used periclase–spinel–Al bricks for the thermal evolution of their components and the formation of novel phase and bonding structure. Under the working atmosphere of RH degasser, metallic Al particles got molten above its melting point, leaving Al rim at their surroundings, and AlN formed in the gaseous state dispersing into overall matrix of periclase–spinel–Al bricks with rising temperature. AlN formed and Mg reduced in their gaseous state germinated MgAlON whisker initially in the original space of metallic Al particles, and MgAlON whisker grew further everywhere in the matrix. A whisker interwoven network has been full of the matrix behind the hot face and toward the cold face of the used bricks, which is a completely novel type of bond and distinguished from traditional ceramic one. The whisker-interwoven network is somewhat like the stripe graphite containing microstructure of magnesia–carbon brick, which results in low wettability and high flexibility. The superior performance of periclase-spinel-Al brick is attributed to such a bonding structure of whisker-interwoven network, which could reduce slag penetration and facilitate thermomechanical stress resistance.

Study on jet formation and penetration behaviour of shaped charge with reactive material composite liner

The shaped charge with reactive material composite liner could not only meet the requirement of the after-effect damage behavior, but also achieve a deeper penetration capability. Based on the platform of AUTODYN-2D code, the jet formation characteristics of the reactive material-titanium liner shaped charge and its penetration behavior to multi-spaced plates were studied. Numerical simulations showed that with increasing of the detonation pressure of explosive, the tip velocity of the composite jet and its penetration capability increased, but the reactive material liner was subjected to the higher pressure and the temperature rise within the elements was larger. In addition, the influence of the standoff and the protective steel block thickness on the penetration behavior of the reactive composite jet was investigated. As the standoff increases from 0.5 CD to 3.0 CD, the penetration capacity of the composite jet increased, but the mass of reactive materials follow-in the spaced plates decreased. With increasing of the steel block thickness, the penetration capability of the reactive material-titanium jet and reactive material follow-in behavior decreased gradually.

Influence of initiation manner on forming characteristics of reactive material jet

The influence of different initiation manners on the forming features of reactive material jets was investigated using the AUTODYN-3D simulation software. The numerical simulation findings demonstrate that, as compared to center point initiation, annular multi-point initiation greatly improves the velocity of the reactive material jet head created, but the expansion impact is more noticeable during the jet generating process. At the head and axis of the jet, there are noticeable low density zones (density less than 1.2 g/ cm3) and high temperature zones (temperature greater than 1000 K) with annular multi-point initiation. This is due to the superposition of several detonation waves, which raises the detonation pressure pressing on the reactive material liner, resulting in faster liner crushing. Furthermore, when the number of initiation points and the distance between initiation positions increases, the range of low density and high temperature regions extends, reducing the reactive material jet’s penetration capabilities.

On Aftereffects of Shaped Charge Comprised of Reactive Material Liner

Two types of shaped charge comprised of reactive material liner, which can generate exothermal reaction by certain external action, were designed to promote the aftereffect. One design contained two layers of liners, which can form a short and wide explosive formed penetrator (EFP). The other design contained three layers of liners, which can form a long and thin EFP. The composition of reactive material is aluminum/polytetrafluoroethylene (AL/PTFE) mixtures. The results of numerical simulation and experiments show that, for steel target with a thickness of 45 millimeter (mm), the EFP generated by the reactive shaped charge comprised with three layers of liners can penetrate more deeply than that with two layers of liners. The former can also perforate two 500 mm spaced steel targets with a thickness of 5 mm, then the residual EFP delivered the reactive material into the oil box. The reactive material released its energy, and ignited the oil.

Effect of compaction water on strength and hydraulic properties of bentonite-based liner

The abundance of pond ash and its resemblance to natural sand encourages its use as a substitute for sand in sand–bentonite (SB) liner material. Compaction water content influences the geoengineering properties of cohesive soil to a great extent. Accordingly, the compaction, strength, permeability and shrinkage characteristics of both pond ash–bentonite (PAB) and SB mixes are investigated at standard and modified Proctor compaction energies at various water contents to support the recommendation of the PAB mixture as an alternative landfill liner. At similar compaction conditions, the PAB mix exhibits higher unconfined compressive strength (UCS) and hydraulic conductivity than the SB mix. The UCS values of mixes compacted on the dry side of optimum are higher than those of mixes compacted on the wet side. Dry-side compacted mixes exhibit a reduction in hydraulic conductivity with permeation time, whereas no substantial reduction in hydraulic conductivity is noticed for wet-side compacted mixes. Furthermore, the volumetric shrinkage of both PAB and SB mixes is within the permissible value of 4%, for a wide range of water variation from the dry to the wet side of optimum. The observed mechanical properties are correlated to the shape of coarse fraction particles and the corresponding microstructural arrangements of the compacted specimens.

Experimental Investigation on the Frictional Behaviour of Banana Peels Composites for Brake Pad Applications

Abstract: Asbestos is used in the manufacture of automobile brake linings, which has negative effects on both people and the environment. As a result, organic brake lining without the use of asbestos material evolved. Asbestos-free brake lining materials come in a variety of forms, and these novel formulations offer excellent performance too. The material used to replace it ought to maintain qualities of standard brake pad risks. A new brake pad was produced using banana peels waste to replace asbestos. The produced composites were mixed with carbon powders, epoxy and hardener in predetermined ratios. The current study is being conducted to create three different samples of brake pads by altering the combination of carbon powder and banana peel powder. The banana peel was varied from 35 to 25 wt. % with a 5 wt. % interval to create test samples. Morphology, physical, mechanical and wear properties of the brake pad were studied. The results showed that the produced banana peel composite of composition carbon 35% and banana peel powder 25% gives better properties compared with other compositions. According to the findings of this study, banana peel particles may be utilized efficiently as a replacement for asbestos in the fabrication of brake pads.