Study on Composite Design Suitable for High Hardness and Strong Abrasive Formation

PDC (Polycrystalline Diamond Compact bit) composite is the most important cutting element of petroleum bit, which performance directly affects the service effect and service life of the bit. During the drilling process, the cutter will produce a large amount of friction heat when cutting the rock, resulting in a sharp increase in the internal temperature of the cutter. When the temperature reaches a certain value, thermal wear and tear are very easy to occur, which will not only cause diamond delamination but also reduce the wear resistance of the cutter. Under the action of impact load, impact failure is more likely to occur, which greatly reduces the service life of the cutter and the rock-breaking efficiency of the drill bit. Therefore, this paper studies the composite interface suitable for high-temperature drilling through the changes of cutting tooth temperature field and stress field with different interface shapes, which shows that the non-planar interface is more suitable for improving the cutting tooth life of composite under the action of comprehensive stress field.

Moisture Vapor Permeability and Thermal Wear Comfort of Ecofriendly Fiber-Embedded Woven Fabrics for High-Performance Clothing

This study examined the moisture vapor permeability and thermal wear comfort of ecofriendly fiber-embedded woven fabrics in terms of the yarn structure and the constituent fiber characteristics according to two measuring methods. The moisture vapor permeability measured using the upright cup (CaCl2) method (JIS L 1099A-1) was primarily dependent on the hygroscopicity of the ecofriendly constituent fibers in the yarns and partly influenced by the pore size in the fabric because of the yarn structure. On the other hand, the moisture vapor resistance measured using the sweating guarded hot plate method (ISO 11092) was governed mainly by the fabric pore size and partly by the hygroscopicity of the constituent ecofriendly fibers. The difference between the two measuring methods was attributed to the different mechanisms in the measuring method. The thermal conductivity as a measure of the thermal wear comfort of the composite yarn fabrics was governed primarily by the pore size in the fabric and partly by the thermal characteristics of the constituent fibers in the yarns. Lastly, considering market applications, the Coolmax®/Tencel sheath/core fabric appears useful for winter warm feeling clothing because of its the good breathability with low thermal conductivity. The bamboo and Coolmax®/bamboo fabrics are suitable for summer clothing with a cool feel because of their high thermal conductivity with good breathability. Overall, ecofriendly fibers (bamboo and Tencel) are of practical use for marketing environmentallyfriendly high-performance clothing.

Mechanical performance of lightweight ceramic structures via binder jetting of microspheres

Geometrically-complex and lightweight ceramic parts manufactured via 3D printing are prospective structures that seem to provide excellent thermal, wear and dielectric performance. In the present work, binder jetted parts based on synthetic lightweight ceramic hollow microspheres were manufactured and evaluated under different testing conditions in order to characterize their mechanical performance. The resulting structures were assessed in terms of quasi-static flexural and compressive strength, and density. Furthermore, microscopy analyses highlighted the composition of the final structures and fracture mechanisms. The printed system mainly consisted of aluminum silicon dioxide, fly ash and traces of metal. The samples yielded similar strength as that achieved on conventional bulk-based 3D printed ceramic structures. It was observed that the strength of the printed microspheres increased by sintering the parts to near-fusion temperatures due to viscous flow of material during sintering. The combination of the proposed process and feedstock represents an attractive manufacturing method for fabricating lightweight structures for applications like composite tooling molds, electromagnetic devices, and biomedical implants.

Effects of hip protective clothing on thermal wear comfort of clothing ensembles

Purpose This paper aims to examine the influence of hip protective clothing on ensemble performance attributes related to thermal comfort. It also explores the effect on protective pads of various materials and the arrangements of material. The thermal comfort characteristics are thermal insulation and moisture vapour resistance. Design/methodology/approach For this research, four ensembles of clothing were used: one ensemble without hip protective clothing and three ensembles with hip protective clothing. A thermal manikin was used to test the thermal insulation and moisture vapour resistance of the ensembles. Findings The findings revealed that incorporating hip protective clothing into the clothing ensembles influenced the thermal resistance and moisture vapour resistance of the ensemble. In the “all zones group,” the influence of the hip protective clothing depended on clothing style, with hipster-style clothing producing insignificant changes. In the “hip zones group” and “stomach and hip zones group,” hip protective clothing strongly influenced the thermal comfort attributes of ensembles. Pad material and volume play important roles in these changes in thermal comfort attributes. Originality/value These outcomes are useful for the design and engineering of hip protective clothing, where maximizing protection while minimizing thermal and moisture vapour resistance is critical for wear comfort and adherence in warm or hot conditions. The designer should consider that material, volume and thickness of protective pad affect the overall thermal comfort attributes of the hip protective clothing.

On rheological, mechanical, thermal, wear and morphological properties of melamine formaldehyde reinforced recycled ABS for sustainable manufacturing

This study outline the procedure of filament fabrication for fused deposition modelling (FDM), based upon rheological, mechanical, thermal, wear and morphological characterization as a case study of acrylonitrile butadiene styrene (ABS) - melamine formaldehyde (MF) composite. It has been ascertained that with increase in proportion of MF in ABS, viscosity is improved and melt flow index (MFI) is reduced significantly. As regards to the wear behavior is concerned it has been observed that ABS-MF (12.5 wt.%) composite has shown minimum weight loss and porosity. For the mechanical properties of the composite, experimental results show increased brittleness of the samples with addition of MF reinforcement. The thermal stability analysis was performed using differential scanning calorimetry (DSC) for virgin ABS and samples having 12.5% MF in ABS and results show the increased heat capacity of the material with increase in MF percentage. Further for sustainability analysis (based upon thermal stability), matrix of ABS-MF12.5% was subjected to three repeated thermal (heating-cooling) cycles and it has been ascertained that no significant loss was noticed in heat capacity of recycled composite matrix. The results are also supported by Fourier transform infrared spectroscopy (FTIR) analysis. Overall the results of the rheological, mechanical, wear, morphological and thermal properties suggested that 12.5% proportion of MF can be reinforced into selected grade of ABS thermoplastic for 3D printing as a sustainable solution.

Intelligent automation of dental material analysis using robotic arm with Jerk optimized trajectory

Many types of biomaterial analysis require numerous repetition of the same operations. We suggest applying the principles of Total Laboratory Automation (TLA) for analysis of dental tissues in in-vitro conditions. We propose an innovative robotic platform with ABB high precision industrial robotic arm. We programmed the robot to achieve 3000 cycles of submerging for analysis of the stability and thermal wear of dental adhesive materials. We address the problem of robot trajectory planning to achieve smooth and precise trajectory while minimizing jerk. We generate different variants of trajectory using natural cubic splines and adopt the NSGA II multiobjective evolutionary algorithm to find a Pareto-optimal set of robot arm trajectories. The results demonstrate the applicability of the developed robotic platform for in-vitro experiments with dental materials. The platform is suitable for small or medium size dental laboratories.

Performance attributes relevant to thermal wear comfort of hip protective garment: influence of comprising pad materials, pad thickness, pad area, and pocket fabric structure

PurposeThis study aimed to evaluate the performance attributes relevant to thermal wear comfort of the commercially available hip protective pads and materials intended for impact protection that can be used for the hip protective pad.Design/methodology/approachThe performance attributes relevant to thermal wear comfort (i.e. dry thermal resistance and evaporative resistance) of the pads were tested using MTNW Integrated Sweating Guarded Hotplate (iSGHP).FindingsIt was found that: the pad with more porous structure has more advantages in terms of evaporative resistance; the permeability index will be higher on the pad with an opening such as a segmented pad; the permeability index will be lower on the thicker and larger pad. The pocket fabric with open structure will have lower dry thermal resistance and evaporative resistance.Originality/valueThe study results showed that the properties of the utilised materials influenced thermal comfort performance. These results could be useful for designing and engineering hip protective garments.