Investigation of Crack Propagation Behaviour in Thin-Rim Gears: Experimental Tests and Numerical Simulations

Thin-rim gears are widely used in industrial fields such as aerospace and electric vehicles due to the advantage of light weight. Yet, the root crack fracture failure of thin-rim gears significantly limits their application and further affects the reliability and safety of high-end equipment. In this work, the root crack propagation behavior of thin-rim gears is experimentally and numerically investigated. The crack initiation position and crack propagation path for different backup ratio gears are simulated using gear finite element (FE) models. The crack initiation position is determined using the maximum gear root stress position. An extended FE method coupled with commercial software ABAQUS is used to simulate the gear root crack propagation. The simulation results are then verified by conducting experimental tests for different backup ratio gears based on a dedicated designed single-tooth bending test device

Evaluation of different hydrocolloids to improve dough rheological properties and bread quality of potato-wheat flour

peer reviewedThe aim of study was to investigate the effect of hydroxylpropylmethylcellulose (HPMC), arabic gum (AG), konjac glucomannan (KG) and apple pectin (AP) at 2% (w/w, potato-wheat flour basis) on the potato-wheat dough (the mass ratio was 1:1) rheological, fermentation properties and its bread quality. The tan δ of potato-wheat dough was significantly increased by adding HPMC compared to those of without adding hydrocolloids (from 0.337 to 0.425), which was close to wheat dough (0.531). Moreover, the dough height during fermentation process was significantly improved by adding hydrocolloids, with the order of HPMC (23.1mm) > AP (19.3mm) > AG (18.6mm) > KG (13.6mm). In addition, the potato-wheat protein bands of potato-wheat dough turned pale by adding hydrocolloids, suggesting higher molecular weight aggregation formed between proteins-hydrocolloids or proteins-proteins after fermentation process. Furthermore, HPMC significantly increased specific volume (from 1.45 to 2.22 ml/g), and hydrocolloids restrained the starch retrogradation of potato-wheat breads.Research Project: Research and Demonstration of Key Technology System of Potato Staple Food (201503001-2

Assembly strategies for rubber-degrading microbial consortia based on omics tools

Numerous microorganisms, including bacteria and fungus, have been identified as capable of degrading rubber. Rubber biodegradation is still understudied due to its high stability and the lack of well-defined pathways and efficient enzymes involved in microorganism metabolism. However, rubber products manufacture and usage cause substantial environmental issues, and present physical-chemical methods involve dangerous chemical solvents, massive energy, and trash with health hazards. Eco-friendly solutions are required in this context, and biotechnological rubber treatment offers considerable promise. The structural and functional enzymes involved in poly (cis-1,4-isoprene) rubber and their cleavage mechanisms have been extensively studied. Similarly, novel bacterial strains capable of degrading polymers have been investigated. In contrast, relatively few studies have been conducted to establish natural rubber (NR) degrading bacterial consortia based on metagenomics, considering process optimization, cost effective approaches and larger scale experiments seeking practical and realistic applications. In light of the obstacles encountered during the constructing NR-degrading consortia, this study proposes the utilization of multi-omics tools to discern the underlying mechanisms and metabolites of rubber degradation, as well as associated enzymes and effective synthesized microbial consortia. In addition, the utilization of omics tool-based methods is suggested as a primary research direction for the development of synthesized microbial consortia in the future

The effects of tensile and compressive dwells on creep-fatigue behavior and fracture mechanism in welded joint of P92 steel

The creep-fatigue interactions on the long-term service damage of P92 welded joint were investigated on the tensile and compressive holdings with a series of applied strains, respectively. The local mechanical properties including hardness, elastic modulus and creep resistance of welded joint were uncovered using nanoindentation. The features of fracture morphology and internal defects after CF tests were studied by scanning electron mi- croscope. Based on the characteristic of microstructural evolution and the variation in local mechanical prop- erties, holding type effects of creep-fatigue interaction on the local creep behavior and fracture mechanism of the welds were systematically investigated

Evaluation of different hydrocolloids to improve dough rheological properties and bread quality of potato-wheat flour

The aim of study was to investigate the effect of hydroxylpropylmethylcellulose (HPMC), arabic gum (AG), konjac glucomannan (KG) and apple pectin (AP) at 2% (w/w, potato–wheat flour basis) on the potato–wheat dough (the mass ratio was 1:1) rheological, fermentation and bread making properties. The tan d of potato–wheat dough was significantly increased upon addition of adding HPMC which was close to wheat dough (0.531). Moreover, dough height during fermentation process was significantly improved on addition of hydrocolloids, with the order of HPMC (23.1 mm)[AP (19.3 mm)[AG (18.6 mm)[ KG (13.6 mm). Protein bands of potato–wheat dough were pale in the presence of hydrocolloids, suggesting the formation of higher molecular weight aggregates formed between proteins–hydrocolloids or proteins–proteins after fermentation process. Furthermore, HPMC significantly increased specific volume (from 1.45 to 2.22 ml/g), and hydrocolloids restricted the retrogradation of starch in potato–wheat breads.Centro de Investigación y Desarrollo en Criotecnología de AlimentosFacultad de Ciencias Exacta

Assembly strategies for polyethylene-degrading microbial consortia based on the combination of omics tools and the “Plastisphere”

Numerous microorganisms and other invertebrates that are able to degrade polyethylene (PE) have been reported. However, studies on PE biodegradation are still limited due to its extreme stability and the lack of explicit insights into the mechanisms and efficient enzymes involved in its metabolism by microorganisms. In this review, current studies of PE biodegradation, including the fundamental stages, important microorganisms and enzymes, and functional microbial consortia, were examined. Considering the bottlenecks in the construction of PE-degrading consortia, a combination of top-down and bottom-up approaches is proposed to identify the mechanisms and metabolites of PE degradation, related enzymes, and efficient synthetic microbial consortia. In addition, the exploration of the plastisphere based on omics tools is proposed as a future principal research direction for the construction of synthetic microbial consortia for PE degradation. Combining chemical and biological upcycling processes for PE waste could be widely applied in various fields to promote a sustainable environment

Revealing Nanoindentation Size-Dependent Creep Behavior in a La-Based Metallic Glassy Film

We systematically studied nanoindentation size effect on creep deformation in a La-based metallic glassy film, including holding depth effect and indenter size effect. Creep displacement was mainly dependent on both holding strain and deformation volume beneath indenter. Under elastic holding, creep strain was merely holding strain–dependent. While for plastic holding, creep strain was greatly enhanced by adopting smaller indenter and/or decreasing holding depth at the same holding strain. A strong nanoindentation size effect on creep resistance was validated. Strain rate sensitivities (SRS) were calculated, which were obviously higher at elastic regions than at plastic holdings. The relationship between SRS value and creep mechanism in metallic glass was discussed