Reduced scale thermal characterization of automotive disc brake

The thermal behaviour of a disc brake is a critical factor that needs to be considered at the design phase. Most researchers utilise a full size brake dynamometer or a simple pin-on-disc rig to experimentally evaluate the performance of a friction pair (disc and pad). In the current paper, a scaling methodology is proposed to evaluate the thermal performance of a disc brake at a reduced scale. The resulting small scale disc brake has the advantage of low cost and reduced development time. The proposed scaling methodology was validated by comparing the results for the full and small scale discs using a conventional brake dynamometer. In addition, a two dimensional axisymmetric transient thermal finite element model was developed using Abaqus software to assist in the validation of the scaling methodology. The numerical simulations confirmed the equivalence between the full and small scale disc thermal performance using the proposed scaling methodology and also gave good agreement with the experimental results. It is concluded that the scaling methodology is an important tool with which to evaluate the thermal performance of disc brakes in the early design phase

Thermal performance of peo coated lightweight brake rotors compared with grey cast iron

Brake rotors play a significant role in converting the vehicle kinetic energy into heat energy that is dissipated through conduction and convection. The automotive industry has been looking for many years to develop lightweight brake rotors to reduce vehicle weight and subsequently improve fuel efficiency and vehicle emissions targets. Uncoated wrought aluminium alloys and metal matrix composite (Al-MMC) rotors have been reported to have insufficient safety margin for most passenger car applications. In this study, the thermal performance of coated and uncoated lightweight aluminium disc brake rotors was investigated numerically and experimentally, using both small scale and full size brake dynamometers. Five small scale solid brake rotors were investigated: grey cast iron, forged aluminium alloy (6082), the same 6082 alloy but with an alumina surface layer applied by plasma electrolytic oxidation (PEO), cast aluminium MMC (AMC640XA), and the same MMC again with PEO alumina surface layer. The disc and pad temperatures, brake pressure, coefficient of friction and brake torque were monitored during the tests for each disc brake material. In addition, a two dimensional axisymmetric finite element model was developed using Abaqus software in order to investigate the temperature distribution through the disc. The 2D FE model demonstrated good overall agreement with the experimental results and showed the same general trends. It was found that the PEO coated aluminium alloy has the best overall performance of the lightweight rotors tested in terms of friction and structural integrity at elevated temperature

Mesenteric lipoma presenting as small bowel volvulus

Many patients will present to the emergency department with bowel obstruction, and here we report a 4-year-old girl, who presented to the pediatric surgery service with intermittent abdominal pain and bilious emesis. Her imaging studies showed a picture of small bowel volvulus without bowel ischemia, with a soft tissue, benign-looking, mesenteric mass, most likely mesenteric lipoma. This case report documents a rare cause of small bowel obstruction in the pediatric age group. Keywords: Mesenteric lipoma, Small bowel volvulus, Pediatric surger

Exploring the Relationship Between Burnout, Resilience, and Dropout Intention Among Nursing Students During Clinical Training in Saudi Arabia

Background The issue of burnout syndrome among health discipline students is gaining heightened attention due to its serious effects, which causes them to have the intention to quit. Despite this, limited studies are available on the extent of burnout and its association with resilience and intention to drop out among clinical-level nursing students. Objective To explore the relationship between burnout, resilience, and intention to quit among nursing students. Methods An online questionnaire was used to conduct a cross-sectional study, targeting nursing students at the clinical level through a nonprobability sample. The participants were required to provide their sociodemographic, Maslach Burnout Inventory, and Connor-Davidson Resilience Scale. Data was analyzed using descriptive, inferential, and correlation tests. Results The study included a group of 564 nursing students and interns, the majority of whom were female at a percentage of 78.9%. Among this group, 65% experienced a high level of burnout, with 42% experiencing emotional exhaustion, 54% experiencing depersonalization (DP), and 77% reporting low personal achievement. A total of 48% of clinical-level students were considering quitting the nursing program. Moreover, the students reported low scores of resilience, with negative correlations observed with DP ( r  = −.12, p  = .04) and positive correlation with low personal achievement ( r  = .43, p  < .001). Conclusion Nursing students and interns faced a significant amount of burnout and showed a desire to drop out nursing program. Their level of resilience was moderately low, and it correlated with burnout subscales DP and personal accomplishment. A collaborative intervention is needed to promote resiliency and alleviate burnout symptoms during clinical training

Material characterisation of lightweight disc brake rotors

Alumina coated lightweight brake rotors were investigated to evaluate the effect of coating properties on their friction performance and thermal durability. An alumina ceramic coating on AA6082 aluminium alloy (Al-Alloy) and on 6061/40SiC aluminium metal matrix composite (Al-MMC) prepared by plasma electrolytic oxidation was studied using a programme of brake dynamometer and material characterisation tests. The results showed that the plasma electrolytic oxidation alumina layer adhered well to the Al-alloy substrate and was more uniform and durable when compared to that on the aluminium metal matrix composite. The plasma electrolytic oxidation layer significantly improved the hardness of the rotor surface for both Al-alloy and aluminium metal matrix composite substrate. The coated Al-alloy disc brake rotor was demonstrated to give good thermal and friction performance up to high rubbing surface temperatures of the order of 550 ℃, but the rotor eventually failed due to temperature build-up at a critical location