Development of carbonaceous tin-based solder composite achieving unprecedented joint performance

Weight reduction and improved strength are two common engineering goals in the joining sector to benefit transport, aerospace, and nuclear industries amongst others. Here, in this paper, we show that the suitable addition of carbon nanomaterials to a tin-based solder material matrix (C-Solder® supplied by Cametics Ltd.) results in two-fold strength of soldered composite joints. Single-lap shear joint experiments were conducted on soldered aluminium alloy (6082 T6) substrates. The soldering material was reinforced in different mix ratios by carbon black, graphene, and single-walled carbon nanotubes (SWCNT) and benchmarked against the pristine C-solder®. The material characterisation was performed using Vickers micro-indentation, differential scanning calorimetry and nano-indentation, whereas functional testing involved mechanical shear tests using single-lap aluminium soldered joints and creep tests. The hardness was observed to improve in all cases except for the 0.01 wt.% graphene reinforced solders, with 5% and 4% improvements in 0.05 carbon black and SWCNT reinforced solders, respectively. The maximum creep indentation was noted to improve for all solder categories with maximum 11% and 8% improvements in 0.05 wt.% carbon black and SWCNT reinforced ones. In general, the 0.05 wt.% nanomaterial reinforced solders promoted progressive cohesion failure in the joints as opposed to instantaneous fully de-bonded failure observed in pristine soldered joints, which suggests potential application in high-performance structures where no service load induced adhesion failure is permissible (e.g. aerospace assemblies). The novel innovation developed here will pave the way to achieving high-performance solder joining without carrying out extensive surface preparations.

Automated System for Restaurant Services

The study proposes a smart restaurant system and analyses its benefits to be able to determine system potential advantages in restaurants. Service time is one of the main criteria that can be improved to enhance the speed of the customer service as well as to increase the number of restaurant visitors. To develop the system, solutions found in scientific literature, software and their different architectures are analysed. It has been found out that it is possible to decrease the average restaurant service load time by 52.76 %. Two hypotheses have been proposed for further research in order to determine how a smart restaurant service system can increase chef’s efficiency and how the use of different algorithms can decrease chef’s workload during peak hours.

Behavior of Reactive Powder Concrete Beams Exposed to Fire

In this paper, the effect of direct fire flame and steel fiber ratio on some mechanical properties and behavior of the relationship between load and deflection of rectangular reinforced concrete beams under the influence of fire exposure was studied. Concrete specimens were exposed to fire at temperatures ranging from (25- 400 ºC). Three temperature levels of (200, 300, 400 ºC) where chosen for exposure duration of 2.0 hours. After conducting the test, it was found that increasing the proportion of steel fibers in percentages 0.5% to 1% and 1.5% decreases the mid-span deflection at service load by 33%, 50% and 37.5 and increases the ultimate load by 36.36%, 41.6% and 53% respectively. After the beams are exposed to fire, it was noticed that the maximum crack width increases with increasing fire temperature.

Behaviour of Reinforced Concrete Beams with and Without Web Openings using Direct Displacement Based Design

This paper describes analysis at the reinforced concrete building that contain web openings at the beam element in certain location. In the analytical modelling, the beams as treated as structural members comprising several segments which has a different dimension, and the equivalent stiffness of the opened beams has been derived. The whole structure including the beams are then analysed by the direct displacement based designed method. As the result from three analytical modelling within the variety of web openings and literature studies are compared with the evaluation of deflections and support reactions under service load. A numerical modelling is also supported the study to corroborate findings. In general, a good agreement has been obtained.

Impact of Live Load on Changes of Backfill Properties of Buried Flexible Steel Railway Structure

The article attempts to assess the changes in the properties of the soil backfill on the basis of studies carried out on the soil compaction indicator for a buried flexible steel structure located in a section of the Pan-European railway line. Initial tests on soil compaction showed that the backfilling does not meet the standard for railway structures. On this basis, it was decided to conduct additional studies taking into account the probability of compacting the soil during the operation of the structure. In order to verify any changes, the compaction indicator tests were repeated after 7 months of use under intensive railway load. On this basis, it can to be stated that there is relationship between the impact of a service load and the parameters of a soil backfill over time. As a result of the intense exploitation of a structure, an increase in the soil compaction index even up to 6.0% (average 2.5%) occurs.

A Novel Convex Hull Coverage Algorithm for the Deployment of Electric Taxi Swap Stations Based on Urban Traffic Flow

Electric taxis have been adopted as a new energy public transportation tool as opposed to traditional taxis in modern city. Designing an efficient swapping station deployment scheme has become an important issue to improve the endurance capability of electric taxis. In this study, based on real operation trajectory data from 3997 taxis in Suzhou city, the battery swapping demand of taxis based on urban traffic flow is obtained to construct a network coverage deployment model under rule constraints, where the main optimization goal is to minimize the number of swapping stations and load balancing. According to this model, a traffic drive planning algorithm based on computational geometry is presented. The experimental results illustrate that the deployment scheme obtained by the proposed algorithm is significantly optimized in terms of the deployment cost and service load and has a lower algorithm time complexity than the typical unified deployment scheme. Therefore, the proposed method can be applied to improve the operating efficiency of the urban electric taxi system.

Development and testing of carbonaceous tin-based solder composites achieving unprecedented joint performance

Weight reduction and improved strength are two common engineering goals in the joining sector to benefit various engineering sectors ranging from transport, aerospace, nuclear to many others. Here, in this paper, we show that the suitable addition of carbon nanomaterials to a tin-based solder material matrix (C-Solder® supplied by Cametics Ltd.) results in two fold strength of soldered composite joints. Single-lap shear joint experiments were conducted on soldered aluminium alloy (6082 T6) substrates. The soldering material was reinforced in different mix ratios (0.01 wt% and 0.05 wt%) by carbon black, graphene and single-walled carbon nanotubes. and benchmarked against the pristine C-solder®. The material characterisation was performed using Vickers micro-indentation, differential scanning calorimetry and nano-indentation whereas functional testing involved mechanical shear tests using single-lap aluminium soldered joints and creep tests. The 0.05 wt.% nanomaterials reinforced solders promoted progressive cohesion failure in the joints as opposed to instantaneous fully disbond failure observed in pristine soldered joints, which suggests potential application in high performance structures where no service load induced adhesion failure is permissible (e.g., aerospace assemblies). The novel innovation developed here will pave the way to achieving low-cost high-performance solder joining without carrying out extensive surface preparations.

Effect of the Service Temperature on the Strength Plasticity and Fracture Mechanism of Cr-Mo Casing Steel

In recent years, the oil and gas well casing is confronted with more complex service environment, and the casing is subjected to higher service load and temperature. In this study, the strength and plasticity of Cr - Mo low alloy casing steel of 80, 90 and 110 steel grades commonly used under high temperature service conditions was studied. The results show that with the increase of temperature, the yield strength and tensile strength of casing steel decreased. The sensitivity of high steel grade to temperature change was higher than that of lower steel grade; with the increase of steel grade, the fracture mechanism of casing steel changed from microporous polymerization fracture induced by large size second phase particles to shear propagation fracture induced by sub grain boundary microporous polymerization. This study has important guiding significance for the service safety and strain design of high grade steel under high temperature conditions.