Influence of Hydrothermal Aging under Two Typical Adhesives on the Failure of BFRP Single Lap Joint

Facing increasingly serious resource crises, energy conservation is becoming the development trend of various delivery vehicles, and lightweight is an important way to achieve energy conservation. In this paper, the basalt fiber-reinforced resin composite material (BFRP) was selected to study the effect of its bonding structure, and it was used to make BFRP-BFRP joints. Two adhesives, Araldite®2012 and Araldite®2015, were used to make single-lap joints and dumbbell-shaped specimens. Aging environments of 80 °C/95% RH and 80 °C/pure water were used for the 0-day (unageing), 10-day, 20-day, and 30-day aging tests, respectively. According to Fick’s second law, the moisture absorption change model of two adhesives was established, and it was found that the water absorption process could be divided into two stages, which explains the precipitation of water molecules and the reaction of water molecules with functional groups. The maximum average failure load and load-displacement curves under different environments and different joints were obtained by using the electronic universal tensile machine, and the exposure time was more important than the effect of humidity. At the same time, the change law of failure strength and ductility were analyzed. The change of Tg (Glass transition temperature) was analyzed by differential scanning calorimetry (DSC) equipment, and the results showed that molecular chain rupture was the reason for the decrease of Tg. It could be seen from the joint failure mode distribution that Araldite®2012 adhesive was easily affected by the environment, and the joint of Araldite®2015 adhesive was affected by the combined effect of the adhesive and BFRP

Effects of Different Surface Treatment Processes on Bonding Properties of Aluminum Alloys under Full Temperature Field Environment

Our aim was to study the influence of the surface treatment process on the mechanical properties of an adhesive. This study takes aluminum alloy 6061 as the substrate; carries out grinding, sandblasting, plasma, grinding + plasma, and sandblasting + plasma surface treatment processes; and chooses the ISR 7008 adhesive to make aluminum alloy butt joints, and the joints Connectors are in −40 °C, −20 °C, 0 °C, 40 °C, 60 °C, and 80 °C environments, respectively (1–3 days of a constant-temperature test). The results show that the plasma surface treatment process helps to improve the activity and hydrophilicity of the bonding surface; the plasma surface treatment process helps to improve the adhesive strength of the joints under the environment of −40 °C and 80 °C; and under the environment of −20–60 °C, the sandblasting + plasma surface treatment process helps to improve the adhesive strength of the joints. By analyzing the infrared spectra of the ISR 7008 adhesive, it was found that the contents of γN−H, νC−C, νC−N, and νC−O were higher in the interval from 25 °C to 80 °C than those in the interval from −40 °C to 0 °C, which resulted in the decrease in adhesive properties

A novel mechanical design of broken rope protection device for enhancing the safety performances of overhead manned equipment in coal mine

A novel mechanical design of the broken rope protection device is proposed to enhance the safety performances of the overhead manned equipment. According to the operating characteristics and functional requirements of the overhead manned equipment, a three-dimensional mechanical model of the broken rope protection device was redesigned. Based on the known parameters of the mechanical model, the stress and strength of the main components are readjusted using the statics characteristics of finite element analysis. To ensure the reliability of the control system of the broken rope protection device, the process of people’s falling, the response performance of the tension sensor, and the signal extraction of the broken rope are analyzed under different loading and unloading speeds. The working principle of the broken rope protection device is expounded in detail. The experimental results showed that better effect is obtained by the new broken rope protection device, which is characterized by good durability, low investment, and high reliability

Numerical Simulation of Droplet Filling Mode on Molten Pool and Keyhole during Double-Sided Laser Beam Welding of T-Joints

The effects of droplets filling the molten pools during the double-sided laser beam welding (DSLBW) of T-joints was established. The dynamic behavior of the keyhole and the molten pool under different droplet filling modes were analyzed. The results indicated that compared with the contact transition, the stability of metal flow on the keyhole wall was reduced by free transition and slight contact transition. At the later stage of the droplet entering the molten pool via free transition, slight contact transition, and contact transition, the maximum flow velocity of the keyhole wall was 5.33 m/s, 4.57 m/s, and 2.99 m/s, respectively. When the filling mode was free transition or slight contact transition, the keyhole collapsed at the later stage of the droplet entering the molten pool. However, when the filling mode was contact transition, the middle-upper part of the interconnected keyholes became thinner at the later stage of the droplet entering the molten pool. At the later stage of the droplet entering the molten pool via free transition, the flow vortex at the bottom of the keyhole disappeared and the melt at the bottom of the keyhole flowed to the rear of the molten pool, however, the vortex remained during slight contact transition and contact transition

Numerical Simulation of Droplet Filling Mode on Molten Pool and Keyhole during Double-Sided Laser Beam Welding of T-Joints

The effects of droplets filling the molten pools during the double-sided laser beam welding (DSLBW) of T-joints was established. The dynamic behavior of the keyhole and the molten pool under different droplet filling modes were analyzed. The results indicated that compared with the contact transition, the stability of metal flow on the keyhole wall was reduced by free transition and slight contact transition. At the later stage of the droplet entering the molten pool via free transition, slight contact transition, and contact transition, the maximum flow velocity of the keyhole wall was 5.33 m/s, 4.57 m/s, and 2.99 m/s, respectively. When the filling mode was free transition or slight contact transition, the keyhole collapsed at the later stage of the droplet entering the molten pool. However, when the filling mode was contact transition, the middle-upper part of the interconnected keyholes became thinner at the later stage of the droplet entering the molten pool. At the later stage of the droplet entering the molten pool via free transition, the flow vortex at the bottom of the keyhole disappeared and the melt at the bottom of the keyhole flowed to the rear of the molten pool, however, the vortex remained during slight contact transition and contact transition

Sequential Paleotetraploidization shaped the carrot genome

Background Carrot (Daucus carota subsp. carota L.) is an important root crop with an available high-quality genome. The carrot genome is thought to have undergone recursive paleo-polyploidization, but the extent, occurrences, and nature of these events are not clearly defined. Results Using a previously published comparative genomics pipeline, we reanalysed the carrot genome and characterized genomic fractionation, as well as gene loss and retention, after each of the two tetraploidization events and inferred a dominant and sensitive subgenome for each event. In particular, we found strong evidence of two sequential tetraploidization events, with one (Dc-alpha) approximately 46-52 million years ago (Mya) and the other (Dc-beta) approximately 77-87 Mya, both likely allotetraploidization in nature. The Dc-beta event was likely common to all Apiales plants, occurring around the divergence of Apiales-Bruniales and after the divergence of Apiales-Asterales, likely playing an important role in the derivation and divergence of Apiales species. Furthermore, we found that rounds of polyploidy events contributed to the expansion of gene families responsible for plastidial methylerythritol phosphate (MEP), the precursor of carotenoid accumulation, and shaped underlying regulatory pathways. The alignment of orthologous and paralogous genes related to different events of polyploidization and speciation constitutes a comparative genomics platform for studying Apiales, Asterales, and many other related species. Conclusions Hierarchical inference of homology revealed two tetraploidization events that shaped the carrot genome, which likely contributed to the successful establishment of Apiales plants and the expansion of MEP, upstream of the carotenoid accumulation pathway

Alignment of Common Wheat and Other Grass Genomes Establishes a Comparative Genomics Research Platform

Grass genomes are complicated structures as they share a common tetraploidization, and particular genomes have been further affected by extra polyploidizations. These events and the following genomic re-patternings have resulted in a complex, interweaving gene homology both within a genome, and between genomes. Accurately deciphering the structure of these complicated plant genomes would help us better understand their compositional and functional evolution at multiple scales. Here, we build on our previous research by performing a hierarchical alignment of the common wheat genome vis-à-vis eight other sequenced grass genomes with most up-to-date assemblies, and annotations. With this data, we constructed a list of the homologous genes, and then, in a layer-by-layer process, separated their orthology, and paralogy that were established by speciations and recursive polyploidizations, respectively. Compared with the other grasses, the far fewer collinear outparalogous genes within each of three subgenomes of common wheat suggest that homoeologous recombination, and genomic fractionation should have occurred after its formation. In sum, this work contributes to the establishment of an important and timely comparative genomics platform for researchers in the grass community and possibly beyond. Homologous gene list can be found in Supplemental material