Experimental investigation of modified co-curing process for carbon fiber/epoxy-laminates

In this study, thermoset-based carbon fiber-reinforced polymer structures manufactured by the so-called modified co-curing process are analyzed and compared to well-established co-curing and co-bonding. The modified co-curing process allows manufacturing geometrically complex parts without traditional core technologies by producing laminates from a un-cured half and a pre-cured half in contrast to using two un-cured halves (co-curing) or a fully cured half plus an un-cured half (co-bonding). The interlaminar fracture toughness under Mode I loading, [Formula: see text], was determined in double cantilever beam (DCB) tests. [Formula: see text] displays a correlation of the degree of cure and the joint properties, with the co-curing laminates having 11% and 33% higher fracture toughness than the modified co-curing configurations. However, modified co-curing in all cases results is superior or equal to co-bonding. To assess the influence of surface properties for the bonding quality, different peel plies were compared with respect to the resulting joint properties. The results with up to 50% loss in [Formula: see text] values indicate the high importance of appropriate surface preparation. Subsequent tests also show that the negative influence of the peel ply on the joint properties can be reversed by abrasive surface treatment. It was found that at higher degrees of partial curing before co-curing, crack growth increasingly occurs in the interface of the bonded laminates. Therefore, the properties of the surface before joining were analyzed and modified to assess its relevance for the bonding properties and the potential for improvement.

Abrasive Surface Finishing on SLM 316L Parts Fabricated with Recycled Powder

Improving the surface roughness quality of 3D printed components, especially metallic ones, which are fabricated from the selective laser melting (SLM) method, has drawn enormous attention from the research community. It should be noted that various studies on this topic have reported that precise surface roughness results can be obtained with various techniques that are indeed not cost-effective. Differing itself from these studies, this manuscript investigates an economical solution for fabricating and surface treating SLM components. Specifically, the inspected specimens were printed with recycled 316L stainless steel powder and treated solely with two abrasive surface finishing methods. In the manuscript, two scanning strategies namely meander and stripes, and three types of surfaces were investigated. Subsequently, their 2D and 3D surface roughness results were elaborated. After the proposed herein abrasive treatment, 3D surface roughness arithmetical mean height of a surface (Sa) value of 0.9 µm can be achieved.

Performance and Reuse of Steel Shot in Abrasive Waterjet Cutting of Granite

Steel shots are suitable for abrasive waterjet rock cutting and recycling because of the high hardness and magnetic properties of steel. This study evaluated the rock-cutting performance and recycling characteristics of steel shot waterjet. The rock-cutting responses of steel shot and garnet were compared at the same waterjet conditions. The used steel shot was collected and the particle-size changes were evaluated before reuse, and its cutting performance was re-evaluated. Overall, the steel shot waterjet yielded improvements in performance in the range of 30–50% compared with the garnet waterjet. Moreover, the recycled steel shot yielded a 50% reduction in cutting performance. Rust was observed on the surface of the used steel shot, the used steel shots were partially destroyed, and the debris on the abrasive surface needed to be removed by drying. The reusable steel shot left on the 80th sieve converged to 60% in each recycling run. The results of this study can be used to reduce the cost of abrasive waterjet and industrial waste.

Development of a Technique for the Study of the Coated Abrasive Surface Wear

Wear of abrasive tools, including coated abrasives, is an important performance feature. A large number of theoretical works and practical studies are devoted to wear assessment issues. In practice, there are many direct and indirect approaches to measuring wear of an abrasive tool. At the same time, many of them have significant shortcomings such as assessment complexity, high time costs, a significant share of manual labor, low measurement accuracy, the need to use specialized equipment, etc. Based on the foregoing, the development of an effective technique for assessing the coated abrasive wear with the use of information and analytical technologies is very relevant and promising. This work is devoted to the development of an original technique for determining the wear of coated abrasives and studying of the tool surface texture. Some results of studies on the wear of coated abrasives of various grain sizes and manufacturers are presented in the article.

Development and Performance Evaluation of a Double Barrel Cassava Grating Machine

In this study, a double barrel cassava grating machine with double discharge outlet has been developed and its performance evaluated and optimized. The machine was designed to ensure very high throughput, easy decoupling and coupling and reduction in grating time. The performance evaluation of the grating machine was carried out using Design Expert Software. A central composite rotatable design of response surface methodology (RSM) was adopted in determining the optimum operating condition of the machine. The optimum operating condition obtained from the machine shows an optimum abrasive surface hole size of 6mm, feed rate of 11.8kg/min and an optimum feed rate of 20.16 kg/min; a through put capacity of 730.8kg/hr. The average mass loss, partially grated and completely grated were found to be 1.43kg, 1.48kg and 22.09kg, respectively for 25kg sample; which indicates effective grating and waste was drastically reduced with an average grating efficiency of 86.23%.

Synthesis of Core–Shell Micro/Nanoparticles and Their Tribological Application: A Review

Owing to the diverse composition, adjustable performance, and synergistic effect among components, core–shell micro/nanoparticles have been widely applied in the field of tribology in recent years. The strong combination with the matrix and the good dispersion of reinforcing fillers in the composites could be achieved through the design of core–shell structural particles based on the reinforcing fillers. In addition, the performance of chemical mechanical polishing could be improved by optimizing the shell material coated on the abrasive surface. The physical and chemical state of the core–shell micro/nanoparticles played important effects on the friction and wear properties of materials. In this paper, the synthesis methods, the tribological applications (acted as solid/liquid lubricant additive, chemical mechanical polishing abrasives and basic units of lubricant matrix), and the functionary mechanisms of core–shell micro/nanoparticles were systematically reviewed, and the future development of core–shell micro/nanoparticles in tribology was also prospected.

Substantiation of work quality indicators of the universal seeds scarificator of the eastern galega (Galega Orientalis)

Eastern galega (Galega orientalis) contains amino acids and vitamins necessary for the normal functioning of the animal organism. In addition, it is a good precursor to many cultures. One of the drawbacks of Eastern galega is the hard shell of the seeds, which leads to increased seed consumption, a prolonged time of seedlings and an irrevocable loss of part of the sown seeds. The most affordable, simple and productive is the mechanical method of violating the tightness of the coating film of seeds. The aim of the study was to conduct comparative experiments with the existing scarifier, to create an improved design of a disk scarifier, which allows to improve the quality of seed treatment, and the theoretical justification of its structural and technological parameters. The original design of the disk scarifier on the seeds of the Eastern galega was investigated. The working bodies of the blades of the scarifier disc and their changing installation angle allows to adjust the contact angle of the seeds with the abrasive surface of the grinding wheel, thereby scratching the hard shell of the seeds without injuring them. In contrast to the used designs of scarifiers, the device under development provides for a pneumatic system for removing dust and impurities from the abrasive surface of the grinding wheel by the air flow and additional seed treatment with the microbiological preparation rhisotorfin. In the study of qualitative indicators of scarification of Eastern galega at an average moisture content of 9%, the following parameters were determined: seed germination,%; the degree of scarification,% and the degree of crushing of seeds,% with disk rotation modes - 700, 900, 1100, 1300, 1500 rpm. The studies have shown high-quality seed treatment compared to its counterpart. In the recommended range of disk revolutions of 900 ... 1100, the proposed scarifier showed a decrease in the degree of crushing of seeds by 0.2 ... 0.4%, an increase in the degree of scarification by 2 ... 3% and the degree of germination by 4 ... 5%. The use of the developed design of the scarifier in international practice will reduce the damage of the treated seeds and increase the yield of legumes.

Development of a multi-roller abrasive Cassava peeling machine

A simple to operate, maintain and affordable multi-roller abrasive cassava peeling machine comprising a feed section, peeling chamber, abrasive surface, tuber discharge chute and waste peel chute was designed, fabricated and evaluated. The machine development was based on engineering standards and specification while considering crop, machine and operational factors to include the physical and mechanical properties of cassava tubers, abrasive property of peeling surface, material and speed of the machine. The machine was evaluated for performance with commonly used varieties NR 8082, 8083, 8208, 09/0581 and UMUCAS 38 having moisture content of 63.33%, 64.50%, 65.40%, 63.50% and 84.33% respectively. The performance evaluation results at a roller speed of 360rpm showed peeling efficiency of 91%, throughput capacity of 2.17kg/min, and a proportion by weight of peel of 0.9%. The cassava peeling machine fabricated, eliminated the drudgery, loss of time and tuber flesh encountered in manual peeling with better product quality when compared with the existing machines.