Safety Critical Components Research Articles

CREATING A CULTURE OF TEAMWORK THROUGH THE USE OF THE TEAMSTEPPS FRAMEWORK: A review of the literature and considerations for Nurse Practitioners

Teamwork is essential for patient safety as highly functioning teams make fewer errors. In high acuity academic medical centers, care delivery is complex and ever-changing, creating a high-risk environment for safety concerns. These intricate settings demand a collaborative approach to care delivery, where structured methods of teamwork and communication are engrained in day-to-day practice. With teamwork being a critical component of patient safety and communication failures likened to preventable medical errors, hospitals are looking to bolster leadership training and improve team dynamics. TeamSTEPPS is a proven method shown to enhance teamwork, communication, leadership, and patient satisfaction. TeamSTEPPS provides an evidence-based framework to optimize patient outcomes by improving communication and teamwork skills among healthcare professionals. Current literature on teamwork and communication demonstrates that nurse practitioners are uniquely positioned to improve team performance through the use of the TeamSTEPPS framework.

EVALUATING AND EMBODYING EXEMPLARY LEADERSHIP

Teamwork is essential for patient safety as highly functioning teams make fewer errors. In high acuity academic medical centers, care delivery is complex and ever-changing, creating a high-risk environment for safety concerns. These intricate settings demand a collaborative approach to care delivery, where structured methods of teamwork and communication are engrained in day-to-day practice. With teamwork being a critical component of patient safety and communication failures likened to preventable medical errors, hospitals are looking to bolster leadership training and improve team dynamics. TeamSTEPPS is a proven method shown to enhance teamwork, communication, leadership, and patient satisfaction. TeamSTEPPS provides an evidence-based framework to optimize patient outcomes by improving communication and teamwork skills among healthcare professionals. Current literature on teamwork and communication demonstrates that nurse practitioners are uniquely positioned to improve team performance through the use of the TeamSTEPPS framework.

An Integrated Method for Bearing State Change Identification and Prognostics Based on Improved Relevance Vector Machine and Degradation Model

Bearings are classified as one of the most safety-critical components in industrial machinery, and their prognostics have proven to be an efficient way to reduce costly unplanned maintenance and guarantee reliability and safety. However, accurate data-driven remaining useful life (RUL) prediction remains a significant challenge because of nonlinear degradation and prediction uncertainty. In this study, an integrated prognostics method is designed for a rolling element bearing to identify its health state changes adaptively and further improve the accuracy of RUL prediction, particularly for its long-term prediction. First, a new health indicator (HI) is proposed based on fuzzy <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$c$ </tex-math></inline-formula> -means clustering and a modified confidence value (CV). The former makes the HI sensitive to state changes, and the latter improves its monotonicity and smoothness. A relevance vector machine (RVM) regression model functions with multikernel widths with a modified degradation model to improve the accuracy of RUL prediction, even when fewer samples are available for long-term prediction. The experimental results of the two case studies indicate that the proposed HI provides a better representation for bearing monotonic and smooth degradation processes while automatically identifying its first predicting time and failure threshold. Moreover, the proposed RUL prediction method exhibits stable performance for various prediction ranges and higher accuracy for bearings with different degradation rates.

Group key agreement protocol for edge computing in industrial internet.

Industrial internet security is a critical component of cyberspace safety. Furthermore, the encryption protocol is a critical component of cyberspace security. Due to the rapid development of industrial internet and edge computing, increasingly more devices are outsourcing their data to cloud servers to save costs. Edge devices should have a secure session key to reduce communication costs and share information. However, most key generation and storage are completed by a centralized third-party organization, which carries some security risks. In this context, this paper will propose a lightweight multi-dimensional virtual iteration of the group key agreement protocol. Group key agreement protocol allows for one-at-a-time encryption and timely key updates without the involvement of a trusted third party, and each device in the network can agreement a large number of keys. According to the analysis of this protocol, it has high security, rapid computation speed, and little storage space.

Empirical Analysis of Mechanical and Thermal Effects on Elastic Workpiece Deformations during Broaching of Safety-Critical Components

Empirical Analysis of Mechanical and Thermal Effects on Elastic Workpiece Deformations during Broaching of Safety-Critical Components

Numerical prediction of machining induced residual stresses when hard cutting AISI 4140

In today’s manufacturing industry, there is a clear focus not only on the accurate manufacturing of geometrically dimensional workpieces but also on maintaining strict tolerances on workpiece rim zone properties. These workpiece rim zone properties, such as grain sizes, deformation zones or, in particular, residual stresses, are generally summarized under the term Surface Integrity. While changes in the Surface Integrity properties of the machined surface can have positive effects, such as compressive stresses induced by hammering, there is at the same time a risk of lasting damage to the rim zone due to a negative change in these properties. As a consequence, a weakening of the workpiece rim zone may later on lead to component failure. For this reason, the design of manufacturing processes for safety-critical components according to the current state of the art is complex, time-consuming and cost-intensive, as it is largely empirical and based on experience. Knowledge-based prediction of process-induced changes in Surface Integrity changes, on the other hand, enables process design times to be shortened and process quality to be increased at the same time. The basis of such a knowledge-based process design is, on the one hand, the knowledge of the physical interactions and, on the other hand, an adequate description of these interactions within the framework of either analytical or numerical models. With the aim of predicting the occurring residual stresses after hard machining of hardened AISI 4140, a numerical chip formation and residual stress model is presented in the following paper and subsequently validated with the aid of experimental test data.

FEA of mechanical behaviour of insulated rail joints due to vertical cyclic wheel loadings

Insulated rail joints (IRJs), safety critical components of railway track, are used to locate trains and broken rails using electrical signalling systems. The bending rigidity of the rail at an IRJ is only 2/3rds that of continuous rail. As a result, stress singularity problems occur at IRJs which therefore degrade faster compared to the continuous rail. Both railhead top surface and sub-surface damage occurs and accelerates the initiation of cracks. Head hardened rails are used to overcome these problems.A thorough study addresses the damage pattern in the railhead sub-surface using a 3D finite element analysis (FEA) employing vertical wheel loadings considering three endpost materials: fibre glass (fb), nylon 66 (ny) and polytetrafluoroethylene (ptfe). A new damage parameter, the vertical residual stress component, is proposed to assess new patterns of railhead damage considering plastic deformation. To rank the influential stress related damage parameters, two other parameters are also considered, namely residual von-Mises and longitudinal stress components. Of these, the residual von-Mises stress component is more prominent with regard to the top surface and sub-surface damage, whereas the longitudinal stress component is responsible for top surface material damage. From these damage patterns, a progressive change in the hardness distribution of railhead material can evolve.

A hybrid experimental and numerical technique for evaluating residual strains/stresses in bonded lap joints

This paper investigates the processing-induced residual strains developed in the adhesive layer of a single lap joint consisting of glass-fiber reinforced polymer (GFRP) adherends bonded with a thermoplastic adhesive , Acrylonitrile Butadiene Styrene (ABS). High-resolution optical fiber sensors were embedded inside the adhesive for in-situ monitoring of strains and temperature during the processing and cooling cycle. The experimental fiber-optic strains are the total strains experienced by the fiber and do not represent the strains in the adhesive because of interfacial effects between the fiber and the adhesive. Hence, a detailed finite element analysis (FEA) model was developed that included the optical fiber within the bondline . The experimentally measured optical fiber strains were first used to calibrate the FE models at each cooling rate. These FE models were then used to predict residual strains and stresses in the bulk adhesive . The FE models showed that the strains calculated along the optical fiber provided a close approximation to the actual strains experienced by the ABS adhesive around it at the center of the overlap region. The experimental technique, with appropriate post-processing, can be used to get a reliable first-hand approximation of the residual strains induced in the bulk adhesive during curing/processing. A critical conclusion from the FE investigation is that, for all cooling rate cases, the von-Mises residual stresses generated inside the bulk ABS adhesive ranged between 65 and 80% of its tensile strength , which showcases the importance of processing-induced residual stresses and their effects on safety-critical components like bonded joints. The hybrid FE-experimental approach used in this work can be extended to other joint geometries and material configurations.

SILENCE IN THE TOWER: ANALYSING THE REASONS OF AIR TRAFFIC CONTROLLERS AVOIDING VOLUNTARY REPORTING

Defined in the organizational behavior literature as employee avoidance of expressing their feelings, thoughts and ideas, the concept of organizational silence refers to the failure to submit reports voluntarily in the context of aviation safety. Due to various factors, aviation employees may avoid reporting. However, managers need voluntary reports from their employees to prevent future accidents. The primary purpose of this study is to find out why air traffic controllers, one of the most critical safety components of flight operation, fail to do voluntary reporting. In addition, whether controllers are involved in real-life voluntary reporting and whether the factors that prevent voluntary reporting vary by demographic variables. The data collected from 212 controllers were subjected to Confirmatory Factor Analysis by using the Statistical Package for Social Sciences (SPSS) 24 program and the reasons for their failure to do voluntary reporting were identified. Furthermore, the study concluded that approximately 27% of controllers did not submit voluntary reporting on unsafe situations or safety-enhancing recommendations they had seen.

A computational study on structural and thermal behavior of modified disk brake rotors

The brake mechanism is one of the inevitable and safety-critical components in an automobile. A proper rotor design and superior heat dissipating material provide better performance during the braking mechanism. In this study, modified ventilated disk brake rotor has been developed with curved vents, holes, and slots and analyzes the stress and temperature distribution. Finite element models of the rotor are shaped with SolidWorks and simulated using ANSYS. Structural and thermal characteristics are compared with a reference disk brake rotor. It is found that the proposed rotors outperformed the conventional one in terms of stress generation, temperature distribution, and factor of safety. Furthermore, computation has been done to find out the best-suitedmaterial for one of the proposed designs. The result provides a physical insight of the structural and thermal characteristics of the geometrically modified rotor that can be implemented in the automotive industry.

Process Induced Preheating in Laser Powder Bed Fusion Monitored by Thermography and Its Influence on the Microstructure of 316L Stainless Steel Parts

Undetected and undesired microstructural variations in components produced by laser powder bed fusion are a major challenge, especially for safety-critical components. In this study, an in-depth analysis of the microstructural features of 316L specimens produced by laser powder bed fusion at different levels of volumetric energy density and different levels of inter layer time is reported. The study has been conducted on specimens with an application relevant build height (&gt;100 mm). Furthermore, the evolution of the intrinsic preheating temperature during the build-up of specimens was monitored using a thermographic in-situ monitoring set-up. By applying recently determined emissivity values of 316L powder layers, real temperatures could be quantified. Heat accumulation led to preheating temperatures of up to about 600 °C. Significant differences in the preheating temperatures were discussed with respect to the individual process parameter combinations, including the build height. A strong effect of the inter layer time on the heat accumulation was observed. A shorter inter layer time resulted in an increase of the preheating temperature by more than a factor of 2 in the upper part of the specimens compared to longer inter layer times. This, in turn, resulted in heterogeneity of the microstructure and differences in material properties within individual specimens. The resulting differences in the microstructure were analyzed using electron back scatter diffraction and scanning electron microscopy. Results from chemical analysis as well as electron back scatter diffraction measurements indicated stable conditions in terms of chemical alloy composition and austenite phase content for the used set of parameter combinations. However, an increase of the average grain size by more than a factor of 2.5 could be revealed within individual specimens. Additionally, differences in feature size of the solidification cellular substructure were examined and a trend of increasing cell sizes was observed. This trend was attributed to differences in solidification rate and thermal gradients induced by differences in scanning velocity and preheating temperature. A change of the thermal history due to intrinsic preheating could be identified as the main cause of this heterogeneity. It was induced by critical combinations of the energy input and differences in heat transfer conditions by variations of the inter layer time. The microstructural variations were directly correlated to differences in hardness.

Field test and numerical analysis of Insulated rail joints in heavy-haul railway

Insulated rail joints (IRJs) are widely used in heavy-haul lines, owing to they are safety critical components of track circuit. However, the IRJs breaks the continuity of the rail, making rail more vulnerable to damage under the long-term wheel-rail interaction. In order to study the performance of IRJs, field investigation and tests were carried out at new IRJ and damaged IRJ. At the same time, a 3D coupling model of heavy haul train-IRJ was established for the further analysis. The result shows that in regards to rail-surface regularity, the new IRJ and the damaged IRJ exhibits convex joint and concave joint respectively. IRJs will gradually turn to concave and dipped in the vicinity of end-post under long-term wheel-rail impact. Since there is a vertical rail displacement difference on both sides of the end-post between the two IRJs, causing the wheel-rail interaction has two different impact modes, of which one is downward height difference impact and the other is upward height difference impact. In normal speed, the impact caused by the damaged IRJ is larger than the new IRJ does and it leads to a severer damage to the whole track. The displacement of sleeper at the damaged IRJ is 7.6 times larger than at the new IRJ due to the void between the sleeper and the ballast. The transfer function of displacement from rail to sleeper at the new IRJ is between 0 and 0.4, while the damaged IRJ is between 0.42 and 6.1. The transfer function can be used as a vital index to evaluate the IRJ service state. With the increase of speed, the displacement of rail and sleeper at the two IRJs increases correspondingly. For the sake of decreasing the occurrence of fatigue damage and plastic deformation of rail and plate as much as possible, the maximum depth of concave should be reined within 0.55 mm.

Higher order training supporting competence, autonomy, relatedness (HOT-CAR): A model to improve learner drivers' higher order skills

Approaches to teaching young Learners to drive on-road often lack a strong, overarching theoretical framework. This paper proposes a transtheoretical model to guide instruction of higher-order skills – that are associated with reduced crash risk in young drivers – including established teaching techniques for effective instruction. Learnings from Self-Determination Theory (SDT) and the Goals for Driver Education framework (widely identified as best-practice but not effectively translated into practice) were integrated into the Higher Order Training supporting Competence, Autonomy, Relatedness (HOT-CAR) model. The model was empirically informed from naturalistic observation of professional in-vehicle lessons (n = 110) and a survey of young adolescent drivers (n = 1627). The HOT-CAR model is presented as a three-component framework that recognises learning to drive occurs within a broader system beyond the Learner and the instructor. The foundation of the model identifies the nature of the relationship between the Learner and the instructor that underlies the success of all other elements. The core of the model is the higher-order driving instruction approach including teaching strategies informed by SDT’s needs-supportive model. The context for the model incorporates some of the immediate considerations relevant to instruction; for example, the graduated driver licensing system, automated vehicle features, and peer influence. An example of the application of the model is provided to reflect the immediate practicality of the HOT-CAR model to driver training. This contributes to the limited road safety literature providing a practical solution to Learner driver training that has potential to reduce the crash risk of young novice drivers. Importantly, the model has potential to be applied and adapted to education and other training environments where higher-order skills are a safety–critical component.

Evaluation of fracture toughness and residual stress in AISI 316L electron beam welds

AbstractWeld residual stress and fracture behavior of 316L electron beam weldments, which are of particular interest in power generation industry, were investigated in this work. Two butt‐weld joints were manufactured in stainless steel 316L plates of 6 mm and 25.4 mm thicknesses. Three complementary methods were used to measure the three orthogonal components of the residual stress in the weld coupons, and fracture tests were conducted on single edge notched bending specimens extracted from different regions of the welds and parent metals.The residual stress measurements showed a maximum value of 450 MPa in longitudinal direction, while it was less than 150 MPa in the other two orthogonal directions, revealing that in our material, and with the chosen weld parameters, the residual stresses were biaxial. The fracture resistance of the weldment and parent material was similar, with material microstructure differences being more significant than the measured residual stresses.The study suggests that 316L electron beam weldments are not susceptible to fracture failure due to their high ductility and ability to relieve residual stresses through gross plasticity. Electron beam welding may therefore be suggested as a reliable manufacturing technology for safety critical 316L components.

A time-domain stepwise fatigue assessment to bridge small-scale fracture mechanics with large-scale system dynamics for high-speed maglev lightweight bogies

Maglev trains with an operation speed higher than 600 km/h show a great advantage during the next generation ground transportation. To tackle the structural integrity of maglev bogies made of forged 6082-T6 aluminum alloys, a time-domain stepwise fatigue assessment (TSFA) approach was proposed to consider complex dynamic fatigue loads. Firstly, a vehicle-bridge coupled maglev vehicle dynamic model was established to obtain the time history of service-simulation fatigue loads. Secondly, these variable-amplitude fatigue spectra were introduced to examine the damage accumulation lifetime of the maglev bogie using classical nominal stress method, the swing bar of high-speed maglev bogies was then identified as the safety critical component. To further enhance the service safety and reliability, the remaining life of the swing bar was investigated using damage tolerance method in terms of a real fatigue failure accident from Shanghai maglev trains. Calculation results indicate that the remaining life is sharply reduced from 34.1 years to 19.7 years when an initial crack length of 3.0 mm is generated at the swing bar. More conservative but practical fatigue life can be acquired when using the new TSFA framework instead of individual damage tolerance or safe-life method.

Modelling the Geometrical Accuracy for Different Part Geometries and Process Parameters when Broaching Fir-Tree Slots in Turbine Disks

Constructive measures in the design of aircraft engines aiming for CO2 and NOx emission reduction result in miniaturization of the components, e.g. the rotating turbine disks. The resulting filigree structures determine a reduction of the resistance against elastic workpiece deformations during the machining process. This leads to increasing demands on the cutting process to maintain the required form and position tolerances. In turbine disks, fir-tree slots as the fixing for the turbine blades are classified as safety-critical components. Currently, the profiled slots are manufactured by broaching. In order to guarantee the required component quality of the resulting fir-tree structure, it is necessary to examine the tool design systematically. By using FE simulations, it is possible to predict geometrical deviations after broaching and to perform counter measurements in tool design.In this paper, an innovative approach is presented, which combines an empirical-analytical cutting force model and numerical FE simulations to model the elastic deformations during the cutting process. Therefore, empirical cutting force information are used as input data for the dynamic FE simulations. The results are then analyzed regarding the achievable form and position tolerances when broaching profile grooves. This paper presents a parameter study on workpiece and process parameters and an evaluation of their impact regarding the geometrical accuracy in broaching.

Deep learning-based optical inspection of rigid and deformable linear objects in wiring harnesses

The wiring harness is responsible for the information and energy flow within automotive vehicles and has become a safety-critical component within the trends of autonomous driving and electrification. As a result, the functionality, correctness, and traceability of the wiring harness need to be ensured with holistic quality assurance in the manufacturing. Addressing this research gap, this paper proposes an image processing pipeline for automated optical inspection of rigid and deformable linear objects in wiring harnesses. The deep learning-based optical inspection is outlined and implemented, the findings are presented, and the effectiveness and the relevance for industrial implementation are discussed.

Fault Injection in Model-Based System Failure Analysis of Highly Automated Vehicles

The active safety control systems of highly automated vehicles for SAE level 3 and higher are still not fully developed and facing some unresolved issues. The deployment of automated driving systems and the functional safety development present challenges in driver – machine control relationship when there is a system failure or malfunction. The current definition of the product development and controllability classes of the road vehicles functional safety (ISO26262) are not feasible in highly automated vehicles (HAV). This research developed an overview of fault or disturbance injection on the steering system of highly automated model to study the impact of steering system sensors malfunction. The approach was to study the fault propagation using a model-based engineering development in a virtual environment of MATLAB. Subsequently, the steering control system of automated vehicle was developed using an adaptive model predictive control structure to study the control system sensors failures on a system-feature level of the vehicle. It was concluded that the steering wheel angle sensor failure has a significant impact on the planned trajectory of the vehicle and thus it was classified as ASIL D, which represents the highest critical safety component and requires comprehensive safety mechanisms to meet the safety goals of the system. The study also introduced a new criterion for controllability classes suitable for highly automated systems based on the global vehicle position relative of the lane marker lines, to deal with the active safety systems and risk handling strategies. The drivers – vehicle control systems are changing significantly in SAE level 3 automated vehicle and above that driving functions are controlled by the vehicle control systems. This presents human factors challenge in this interactive system with moving to SAE levels 4 and 5. Hence, several human machine interfaces and scenario-based testing are introduced to mitigate any risk or safety uncertainty resulting from control handing-over between the driver and the vehicle control system.

State-of-The-Art Cooling and Lubrication for Machining Inconel 718

Abstract Inconel 718 is the most used nickel superalloys with applications in aerospace, oil and gas, nuclear, and chemical industries. It is mostly used for safety-critical components where the condition of the surface is a significant concern. The combination of mechanical, thermal, and chemical properties of Inconel 718 has made it a difficult-to-machine material. Despite recent advances in machining Inconel 718, achieving desired surface integrity with prescribed properties is still not possible. Different machining environments have been investigated for improving the machinability of Inconel 718 and enhance the surface integrity of machined components. This paper provides a new investigation and classification into recent advances in the machining of Inconel 718 regarding surface integrity, mostly concentrated on turning applications. The major findings and conclusions provide a critique of the state-of-the-art in machining environments for Inconel 718 together with future directions for research. Surface integrity has been evaluated in terms of surface topology as well as mechanical and microstructural properties. The impact of various cooling and lubrication methods has been investigated. It has been found that surface integrity is affected by the thermomechanical conditions at the cutting zone which are influenced by the cutting parameters, cutting tool, tool wear, and cooling/lubrication condition. The current technologies are incapable of delivering both productivity and sustainability while meeting surface integrity requirements for machining Inconel 718. High-pressure cooling has shown the potential to enhance tool wear at the expense of higher power consumption.

Fusion of multi-view ultrasonic data for increased detection performance in non-destructive evaluation.

State-of-the-art ultrasonic non-destructive evaluation (NDE) uses an array to rapidly generate multiple, information-rich views at each test position on a safety-critical component. However, the information for detecting potential defects is dispersed across views, and a typical inspection may involve thousands of test positions. Interpretation requires painstaking analysis by a skilled operator. In this paper, various methods for fusing multi-view data are developed. Compared with any one single view, all methods are shown to yield significant performance gains, which may be related to the general and edge cases for NDE. In the general case, a defect is clearly detectable in at least one individual view, but the view(s) depends on the defect location and orientation. Here, the performance gain from data fusion is mainly the result of the selective use of information from the most appropriate view(s) and fusion provides a means to substantially reduce operator burden. The edge cases are defects that cannot be reliably detected in any one individual view without false alarms. Here, certain fusion methods are shown to enable detection with reduced false alarms. In this context, fusion allows NDE capability to be extended with potential implications for the design and operation of engineering assets.