Failure Modes Research Articles

Environment Risk Assessment of Healthcare Waste Using Ensemble Learning Technique-Based EFMEA

Healthcare waste (HCW) affects the sustainable development of the environment greatly. The choice of medical waste treatment methods has become a significant concern for public health and safety due to the rapid surge in the volume and diversity of medical waste. As an important aspect of environmental risk assessment (ERA), HCW risk assessment plays a crucial role in environmental protection to develop sustainability strategies. Failure Mode and Effects Analysis (FMEA) has been extensively utilized in HCW risk assessment in the past few decades. In this paper, we aimed to address the limitations of traditional FMEA while incorporating the benefits of diverse FMEA methods and employ a novel ensemble learning technique-based FMEA method to perform risk assessment of HCW. A real-world case of HCW risk assessment is investigated for the verification of the performance and effectiveness of the ensemble learning technique-based Environment FMEA (EFMEA). Result of the case study shows that this ensemble learning technique-based EFMEA can provide a more reliable assessment result for HCW risk management.

Bending test of long-span ultra-shallow floor beam (USFB) with two lightweight concretes

This paper presents the bending behaviour of a partially encased ultra-shallow floor beam (USFB) with two types of lightweight concrete. The beam was fabricated by welding two asymmetric Tees together along the web to create a beam with multiple circular openings that act as ‘plug shear connectors’ with the concrete encasement. The bending resistance of the plug-shear connection system was obtained by testing a composite USFB for a beam span of 7.2 m, half of the span being made with a lightweight concrete slab and the other half span with an ultra-lightweight concrete slab. Analysis of the four-point bending tests was carried out to determine the increase in bending resistance due to composite action and the contribution of the longitudinal shear connection due to the concrete plug passing through the web openings combined with additional tie bars. Calculations of the properties of the USFB with the two types of lightweight concrete were made according to SCI documentation and Eurocode 4. It was observed that the deflections were predicted accurately by the elastic properties and that the failure mode was by concrete crushing before the plastic bending resistance of the composite section had been developed. It was also shown that the cracked section properties should be used for the deflection analysis.

Study on the Microstructure Evolution and Strength Deterioration of Powder Crystal Dolomite under Dissolution

To study the influence of water–rock interactions on the deterioration of rock, particularly the problems of the complex dissolution mechanism of dolomite and the difficulty in establishing chemical damage, dolomite obtained from a tunnel in Yuxi City was utilized. The macroscopic and microscopic dissolution characteristics of dolomite were analyzed using an indoor dissolution test combined with the hydrochemical characteristics of the study area, which were found to be favorable for dissolution. The dissolution of dolomite indicates the chemical decomposition of dolomite crystals, and the crystal failure mode is divided into intergranular dissolved pores and intracrystalline micropore development. Under various pH conditions, as H + is immersed in the rock sample, the failure mode of the rock sample develops from longitudinal cracks to transverse and longitudinal staggered cracks. Based on the aforementioned conclusions, in addition to the principle of chemical kinetics and the generalized Lemaitre strain equivalence principle, a damage model suitable for dolomite chemical erosion was defined. The fitting degree between the calculated value of uniaxial compressive strength and the experimental value reaches 98%, which is of excellent prediction accuracy and reliability. The model for dolomite chemical damage proposed herein provides a theoretical basis for dolomite dissolution damage; the theory of rock chemical damage is thereby enhanced.

Shear behavior of seawater sea-sand concrete beams reinforced with BFRP bars after seawater dry-wet cycling

The shear behavior of 27 basalt fiber-reinforced polymer reinforced seawater sea-sand concrete (BFRP-SSC) beams after seawater dry-wet cycling was comprehensively investigated. Parameters considered included stirrup diameter and spacing, shear span-to-depth ratio, stirrup surface treatment, cycling duration, concrete cover thickness, and seawater temperature. Results indicate that seawater dry-wet cycling increases cracking load and decreases bending stiffness in BFRP-SSC beams. Increasing shear span-to-depth ratio from 1.55 to 2.35 led to load reductions of 31.3 % and 49.7 % at 6.5 mm mid-span deflection. Seawater dry-wet cycling, particularly temperature and duration, significantly impacts the mechanical properties of stirrups. This results in diminished shear contribution and reduced efficacy in inhibiting diagonal crack propagation, leading to a shift in beam failure mode from diagonal compression failure to shear compression failure and diagonal tension failure. Increasing cycling duration from 60 to 120 days decreased tensile strength retention by 19.1 % and 33.3 % respectively. Based on experimental data, Arrhenius theory, and the time shift factor (TSF) method, a predictive model was developed for the shear capacity retention of beams subjected to seawater dry-wet cycling. Results indicate that after 100 years in a tidal environment (70 % and 90 % relative humidity), shear capacity damage factors of 0.77 and 0.52, respectively, can be applied to account for the impact of seawater dry-wet cycling on the shear capacity of BFRP-SSC beams.

Quasi-static compression response of foldcore sandwich structure based on core evolution

Due to its superior performance, the foldcore structure has the potential to replace traditional honeycomb materials. Single-ridgeline V-shaped, double-ridgeline M-shaped, and curved S-shaped foldcore structures were designed based on the principle of origami by controlling areal density. Three foldcore sandwich structures were fabricated from GFRP by hot compression molding method, and PU foam-filled foldcore sandwich structures were also prepared by in-situ foaming. The strength analysis models of the three types of foldcore under out-of-plane compression load were established through differentiation and integration. Subsequently, the quasi-static compression performance and failure modes of the foldcore were investigated through experiments. The analysis model has a certain degree of accuracy in predicting the strength of the structure. It was found that the primary failure mode of V-shaped foldcore under out-of-plane compressive loading was wall buckling. In contrast, the M-shaped foldcore had higher buckling resistance and the failure mode changes from buckling to crushing. S-shaped foldcore had a higher compression strength, and its failure mode changed to wall shear fracture. In addition, lightweight foam filling improved the failure stress of the foldcore.

Shaking Table Test Study of Dynamic Response and Failure Mode of Liquefiable Layer Slope Under Earthquake

As a kind of special terrain, the landslide disaster generated by liquefiable layer slopes under earthquake has become a major engineering challenge due to its large scale and long slip distance. In order to study the seismic response and damage mode of liquefiable layer slope, this paper follows the research line of “geological generalization, physical modeling, and result analysis”, and takes the liquefiable layer slope in the upper reaches of the Yellow River Class secondary terrace as the object of study, generalizes the physical model of the slope, and carries out shaking table test. Based on the PGA amplification coefficient, Fourier analysis and HHT time–frequency characterization of the model slope, it was found that the PGA amplification coefficient increases gradually along the slope height, reaches the maximum value at the top of the liquefiable layer and then decreases gradually, which indicates that the liquefiable sand layer has an obvious energy dissipation effect, and on the horizontal direction of model slope is a tendency to the surface effect; the seismic waves at the discontinuous interface change drastically, and the Hilbert time–frequency spectrum transforms from multiple peaks to a single peak; with the increase of the intensity, the intrinsic frequency of the overall model decreases, and the high-frequency component within the liquefiable sand layer decreases from 5–15[Formula: see text]Hz to 0–5[Formula: see text]Hz, indicating that the liquefiable layer has a filtering effect; the damage process of the liquefiable layer slope is the tensile crack at the top of the slope — seismic subsidence at the top of the slope — the shear yielding at the angle of the slope — shear surface penetration at the slope face — overall slope instability and flow-slip damage. The research results will provide a reference for the study of the disaster mechanism of the liquefiable layer slope.

Multi-objective optimization of bias current coefficient based on NSGA- III for active magnetic bearing with redundant electromagnetic actuators

PurposeThe multi-objective optimization configuration strategy is proposed due to the configuration of EMAs in fault-tolerant control of active magnetic bearing with redundant electromagnetic actuators involving high-dimensional, nonlinear, conflicting goals.Design/methodology/approachA multi-objective optimization model for bias current coefficients is established based on the nonlinear model of active magnetic bearings with redundant electromagnetic actuators. Based on the non-dominated sorting genetic algorithm III, a numerical method is used to obtain feasible and non-inferior sets for the bias current coefficient.Findings(1) The conflicting relationship among the three optimization objectives was analyzed for various failure modes of EAMs. (2) For different EMAs' failure modes, the multi-objective optimization configuration strategy can simultaneously achieve the optimal or sub-optimal effective EMF, flux margins, and stability of EMF. Moreover, the characteristics of the optimal Pareto front are consistent with the physical properties of the AMB. (3) Compared with the feasible configuration of C0, the non-inferior configurations can significantly improve the performance of AMB, and the advantages of the multi-objective optimization configuration strategy become more prominent as the asymmetry of the residual supporting structure intensifies.Originality/valuei) Considering the variation of the rotor displacement during the support reconstruction, a decision-making model that can accurately characterize the dynamic performance of AMB is presented. (ii) The interaction law between AMB and rotor under different failure modes of EMAs is analyzed, and the configuration principles for redundant EMAs are proposed. (iii) Based on the dynamic characteristics of AMB during the support reconstruction, effective EMF, energy consumption, and the Pearson correlation coefficient between the desired EMFs and the decoupled control currents are used as objective functions. iv. The NSGA-III is combined with the decision-making model to address the multi-objective optimization configuration problem of C0.

Additive manufacturing and mechanical analysis of multi-material polymer parts combining thermosets and thermoplastics

Multi-material additive manufacturing (AM) represents one of the most promising solutions to target the contemporary demand for complex products with high individuality and inherent functionalities. Besides continuous advances in machinery and the available material spectrum, a substantial aspect of multi-material AM is still underrepresented: the simultaneous combination of thermosets and thermoplastic within a single AM process. A promising technology in this regard is the newly developed Fusion Jetting (FJ) process. This investigation focuses on the combination of acrylate-based photopolymers (thermoset) and thermoplastic polyurethane (TPU) with FJ. Tensile specimens are built with strategic variations of the process parameters and experimentally analyzed to derive beneficial processing conditions. A proof of concept is delivered by demonstrating a significant increase in Young’s modulus of TPU specimens from approximately 65 to 160 MPa through integration of photopolymer reinforcements. Further experiments regarding variable layer heights and laser powers identify an optimum layer height of 100 µm along with a tolerable laser power of 15 W for maximum mechanical properties. An overall challenging aspect of the FJ process is the presence of unwanted delamination between reinforced and non-reinforced layers. The failure mode is observed during tensile testing on multiple multi-material specimens of this investigation. The origin of delamination can be correlated to the deviation of integrated reinforcements from their originally intended dimensions as well as the unwanted crystallization within reinforced layers. First, countermeasures to minimize delamination are identified, such as decreasing the rotational increment of the laser hatch orientation from 90 to 10° per layer.

Factors affecting bond behavior between ECC and steel rebars

Engineered cementitious composites (ECC) have attracted significant attention, in the civil engineering domain, due to their appealing characteristics. A main factor governing ECC’s performance is the steel-to-concrete bond behavior. However, there is yet dire need to mend the knowledge gap in this venue. This study aims to investigate the influence of the ECC associated traits onto the aforementioned bond behavior: compressive strength, bonded length-to-rebar ratio, rebar diameter, ECC cover thickness (and confinement level around steel rebar at bonded length region). To fulfill this purpose, eight beam-end specimens were prepared and tested. Results showed that (i) ECC compressive strength had the greatest impact on the ultimate bond stress; followed by (ii) the bonded length-to-diameter ratio, and (iii) the cover thickness (whilst adding steel stirrups). The latter’s performance was marginal. In descending order, the influence amounted to 16.5 %, 12 % and 3.5 %, respectively, for a variant range of input-parameter change. As regards the failure mode: the superior tensile properties of ECC led to the occurrence of a pull-out scheme rather than the anticipated splitting mode of failure. This diminished the role of cover thickness and stirrups, in this regards. Finally, new models are developed to predict the bond-slip behavior for ECC-to-steel rebar. The developed models demonstrated adequate agreement with experimental results.

Efficiency Analysis of Die Attach Machines Using Overall Equipment Effectiveness Metrics and Failure Mode and Effects Analysis with an Ishikawa Diagram

Efficiency Analysis of Die Attach Machines Using Overall Equipment Effectiveness Metrics and Failure Mode and Effects Analysis with an Ishikawa Diagram

Risk management of radioiodine treatment in differentiated thyroid cancer

IntroductionPatient safety is paramount in providing quality healthcare and constitutes a global concern for healthcare systems. Radioiodine treatment to patients with well-differentiated thyroid cancer is not without risks. The aim of this study is to identify, evaluate and mitigate the risks associated with this procedure. Materials and MethodsA single-centre descriptive study was conducted in which risk management was carried out by establishing a risk map using FMEA methodology. ResultsBased on the process map 6 sub-processes and 23 failure modes in the three phases of the treatment process were analysed. According to risk priority number (RPN), the sub-process with the highest risk was administrative management (RPN 82), followed by treatment per se and post-treatment imaging (both with RPN 70). An overall process RPN of 300 (156 pre-treatment, 74 treatment and 70 post-treatment) was obtained. Failures directly related to the patient pose a high risk. The implementation of verification systems, performing tasks earlier and providing quality medical information are the most relevant preventive measures to be implemented. ConclusionsThe application of the FMEA methodology in the risk management for radioiodine treatment is a valuable tool for improving the quality and safety of this process. The risk map has been able to identify failures at different stages, assess their causes and effects, prioritise the risks identified and implement preventive and corrective measures that can be monitored, ensuring the effectiveness of the actions taken.

Detection of Demagnetization Faults in Electric Motors by Analyzing Inverter Based Current Data Using Machine Learning Techniques

Demagnetization of the rotor magnets is a significant failure mode that can occur in permanent magnet synchronous machines (PMSMs). Early detection of demagnetization faults can help change system parameters to reduce power output or ensure safety. In this paper, the effects of demagnetization faults were analyzed both in simulation and experiments using the example of drone motors. An approach was investigated to detect even minor demagnetization faults that does not require any additional sensing effort. Machine learning (ML) techniques are used to analyze the phase current data directly received from the inverter to enable anomaly detection. For this purpose, the phase current is transformed by the Fast Fourier Transform (FFT), the spectral data is then reduced in dimensionality, followed by an anomaly detection algorithm using a one-class support vector machine (OC-SVM). To ensure simplified initialization of the ML model without the need for training sets of damaged drives, only data from magnetically undamaged motors was used to train the models for anomaly detection. Different selections of considered harmonics and different metrics were investigated using the experimental data, achieving a precision of up to 99%, a specificity of up to 98%, and an accuracy of up to 90%.

Experimental study of bond behavior of geopolymer concrete under different curing condition using a pull-out test

Researchers recently have focused on geopolymer concrete as it has several advantages compared to traditional Portland cement, such as lower carbon footprint, high early strength, chemical resistance and long-lasting structural performance. This paper designed 192 pull-out specimens to investigate the influence of factors on the bond-slip behavior between geopolymer and steel bar such as curing condition (ambient and 80 °C for 7 hours), longitudinal rib angle, the position of longitudinal bar, bar diameter (12 mm and 24 mm), stirrup usage (with and without stirrup) and bond length (2d and 4d). The maximum bond strength, bond failure modes, and bond stress-slip relations were discussed. The test results showed that the longitudinal rib angle, and the position of rebar play a vital role in determining the bond strength as well as the bar diameter. In comparison with the specimens without the stirrup, the bond performance of specimens with stirrup increased more significantly, and this phenomenon became even more pronounced as the bar diameter increased. The stirrup usage in samples under ambient and heat cure increased the bond strength by an average of 45 % and %40, respectively. Moreover, it has been determined that the curing conditions have a significant effect on the bond performance, as especially the compressive and tensile strengths of the samples under heat cure improve. In samples exposed to both ambient and heat cure, doubling the bond length increased the bond strength by 70 %. Furthermore, increasing the bar diameter increased the bond strength of the samples exposed to ambient and heat curing by a maximum of 84 % and 79 %, respectively. The findings lay the groundwork for understanding the bond behavior of geopolymer, which is critical for the successful application of geopolymer-bonded rebar.

Flexural behavior of laminated H-beams in modular constructions: Numerical and analytical studies

Modular steel construction (MSC) has become an important development direction of the construction industry thanks to the faster construction speed and recyclability. The laminated steel beam is one of the key structure characteristics of MSC, which can enhance the structural integrity by strengthening the interaction between the adjacent beams in vertically stacked modules. In this study, numerical and analytical studies were carried out to explore the flexural behavior and design method of the laminated H-beams in MSC. Firstly, finite element models were established and verified based on the previous experimental study on flexural behavior of the laminated square steel tube beams and laminated channel steel beams. Afterwards, finite element analysis was conducted on flexural behavior of the laminated H-beams with different connecting bolts. The results showed that the flexural capacity and stiffnesses of the laminated H-beams were significantly improved by increasing the number of the connecting bolts in the bending-shear sector. The flexural behavior of the laminated H-beams was discussed including the failure mode, load-deflection curves and slippage of the superimposed surface to reveal the co-bending mechanism. In addition, parametric analysis was performed to reveal the influence of the position, number and diameter of the connecting bolts on flexural behavior of the laminated H-beams. Finally, a theoretical model on flexural capacity of the laminated H-beams was developed to determine the neutral axis and derive the flexural capacity of the laminated H-beams. The calculation formulas were verified to be reliable by comparing the theoretical analysis results with the numerical ones. The present study is beneficial to consummating the mechanical behavior and design method of MSC.

Mechanical behavior and thermal damage characterization of granite after flame jet-water cooling treatment

Flame jet-assisted mechanical rock drilling is expected to solve the hard-rock crushing challenges in underground engineering such as mining, tunneling, and drilling. Therefore, it is important to investigate mechanical behavior of the rock after flame jet-water cooling treatment. In this paper, granite blocks were subjected to flame jet-water cooling treatment, which means the rapid heating of the granite using a flame with a temperature of 1564 °C, followed by water cooling. Then, physico-mechanical behaviors of samples at different distances (all the distances mentioned later mean the vertical distance between the sample axis and the flame jet-water cooling path) were measured. Results showed physico-mechanical parameters of the sample increased as the distance increased. The Vp (P-wave velocity), UCS (uniaxial compressive strength) and BTS (Brazilian tensile strength) of the samples increased from 3171.7 m/s, 84.84 MPa and 5.01 MPa at 0 mm to 3619.3 m/s, 145.86 MPa and 7.30 MPa at 70 mm, respectively. Meanwhile, physico-mechanical parameters of samples at 70 mm all reached more than 95 % of those of untreated samples. As the distance increased, cumulative AE counts at peak stress gradually enhanced, and failure modes of uniaxial samples shifted from shear to tensile splitting failure. The SEM (scanning electron microscope) images illustrated that the closer to the flame jet-water cooling path, the more thermal cracks produced in the sample. Meanwhile, the damage factor can well characterize the thermal damage degree of granite. According to the variation of physico-mechanical parameters and SEM images of samples with distances, it can be assumed that the thermal damage width of granite after flame jet-water cooling was about 140 mm. It was much greater than the 50 mm width of spalling pits, which greatly increased the feasibility of thermal-assisted mechanical rock drilling. The tensile stress induced by the temperature gradient below the spalling pit is the fundamental cause of thermal damage to the rock, which is further aggravated by water cooling. The findings can provide some guidance for flame jet-assisted mechanical rock drilling.

Using the Failure Mode and Effect Analysis Tool to Improve the Automatic Stop Order Process

Introduction Automatic stop orders (ASOs) in computerized prescription order entry (CPOE) systems predefine the length of treatment. This can improve resource use for select therapies (e.g., empirical antibiotics). However, root cause analysis of dose omission errors identified inappropriate ASO-directed termination of medications without prescriber notification. This quality improvement initiative aimed to identify potential failures of the medication ASO processes to develop a new workflow and anticipate issues that may arise after implementation. Methods A failure mode and effect analysis (FMEA) was conducted following Institute of Healthcare Improvement guidance. A multidisciplinary ASO-FMEA team reviewed the existing workflow. Failure modes, risk priority numbers (RPNs), and interventions were identified and assessed. The RPNs calculated for the proposed new workflow (assuming all recommendations were implemented) were compared with those of the existing workflow. Results Eight failure modes, 17 effects, and 31 causes were identified in the five workflow steps (mean RPN 365.4; median 280). Specific, measurable, achievable, realistic, and time-bound interventions were proposed. Assuming successful implementation of all recommendations, the RPNs of the proposed workflow (mean 117.6; median 112) were significantly lower (p < 0.05). Conclusion When modifying existing CPOE systems, FMEA may identify possible failures that can be addressed before the implementation of a new process. This may prevent errors, improving medication safety. Regardless, continuous audit and monitoring are required to ensure the effectiveness of implemented changes.

A method for empirically validating FMEA RPN scores in a radiation oncology clinic using physics QC data.

In failure modes and effects analysis (FMEA), the components of the risk priority number (RPN) for a failure mode (FM) are often chosen by consensus. We describe an empirical method for estimating the occurrence (O) and detectability (D) components of a RPN. The method requires for a given FM that its associated quality control measure be performed twice as is the case when a FM is checked for in an initial physics check and again during a weekly physics check. If instances of the FM caught by these checks are recorded, O and D can be computed. Incorporation of the remaining RPN component, Severity, is discussed. This method can be used as part of quality management design ahead of an anticipated FMEA or afterwards to validate consensus values.

Numerical simulations on compression behaviors of the laminated shale based on the digital image technology and the discrete element method

As an unconventional reservoir sedimentary rock, shale contains a series of layers and various microstructures that lead to complex mechanical properties, such as the anisotropy of stiffness and strength. This study is directed towards the anisotropy caused by the microstructures of the shale, employing the 2D particle flow code (PFC2D) to explore stiffness, strength, failure mode, and micro-crack evolution. More realistic microstructures and the calibration of microscopic parameters of the shale are reasonably considered through the computed tomography (CT) images and mineral analysis. The corresponding numerical simulation results are fully compared with the experimental results. In what follows, the sensitivity analysis is conducted on the key microscopic parameters and microstructure characteristics in numerical samples with laminated characteristics. The results show that the influence of microscopic parameters of the parallel bonding model on macroscopic parameters is related to the layering angle and the face type, and the microstructures and initial cracks of numerical samples can considerably affect the macroscopic mechanical behaviors of the laminated samples. Next, the effect of confining pressure on the mechanical properties of layered shale is also discussed based on the numerical results. These findings highlight the potential of this approach for applications in micro-scaled models and calibration of microscopic parameters to probe mechanical behaviors of the laminated rock.

Study on mechanical behavior of inclined cemented tailings composite backfill (CTCB) under uniaxial compression

The goaf volume in the vacancy method of hard rock mines is significantly larger than the filling capacity, forming layered and inclined planes during the large-scale filling process. This results in unclear mechanical impact mechanisms on the backfill. To investigate the effect of interface inclination angle on the mechanical behavior of backfill, a set of cemented tailings composite backfill (CTCB) samples with interface inclination angles of 15°, 30°, and 45° are prepared. Uniaxial compression tests and digital image correlation techniques are used to investigate the influence of various interface inclination angles on the strength, deformation behavior, and failure mode of the CTCB. The results show that: (1) The uniaxial compressive strength (UCS) of the CTCB weakens with increasing interface inclination angle but consistently shows exponential growth with curing age (CA) regardless of the interface inclination angle. (2) The interface inclination angle controls the behavior and classification characteristics of the stress-strain curve of CTCB samples, and the increase of interface inclination angle weakens the elastic modulus. (3) The interface inclination angle significantly influences the failure mode and classification characteristics of the samples compared to CA and tailing-to-cement ratio (TCR), with shear slip failure induced by the former and axial splitting failure induced by the latter. The research provides a theoretical basis for understanding the mechanical behavior and stability control of inclined CTCB in underground mining.

Experimental and numerical investigations on the bending capacity of cold-formed steel box headers

The study investigates the bending strength of tracks of box headers beyond AISI, which considers the capacity of individual channels alone. Both experimental and FEM are used, and the results are compared to AISI. The findings highlight tracks' significant role in the overall bending capacity. AISI is found to be conservative by 34% to 152%. Failure mode is different from code theoretical expectations for a single channel. Fastener close spacing marginally improves the capacity, while side fasteners offer significant enhancement, but track widening limits this enhancement. A modification to AISI is proposed considering track strength, with outcomes showing good accuracy.