Common Failure Modes Research Articles

Efficacy of carbon nanotube bucky paper for interlaminar damage sensing in composites and fiber‐metal laminates

AbstractDelamination between adjacent laminas and debonding at the fiber/metal interface are common failure modes in composites and fiber‐metal laminates (FMLs). During the initial stages, these flaws are difficult to detect because of their small size and limited applicability of existing damage‐sensing techniques due to the associated heterogeneity and anisotropy with composites and FMLs. Here, we demonstrate a feasible interlaminar damage‐sensing strategy in composites and FMLs using carbon nanotube (CNT) bucky paper (BP). The microstructure dependence of BP electrical conductivity allows it to sense the damage under varying loading conditions. The accuracy of strain sensing with BP is similar to the commercial 120 Ω strain gauge. The BP sensor accurately detects the interlaminar damage in composites (glass fiber/epoxy, carbon fiber/epoxy) and glass fiber–Al (GLARE) laminates. The delamination is marked by a steep rise in the electrical resistance of BP‐modified coupons. Moreover, the sensing capability of the BP sensor is found to be independent of the electrical conductivity of the tested coupons. Thus, the present approach is applicable to sense the interlaminar damage in a much wider class of structural composites and FMLs.Highlights Timely and accurate damage detection in composites is important to ensure their structural integrity. Electrical resistance of bucky paper (BP) varies with deformation. Performance of the BP sensor is comparable to the strain gauge at small strains. BP accurately captures interlaminar damage in composites and FMLs. BP is suitable for damage sensing in a wider class of layered materials.

Fe-SMA for enhancing both structural robustness and seismic resilience: A pioneering study

Low-cycle fatigue (LCF) failure has been recognized as one of the most common failure modes of structures experiencing a major earthquake; on the other hand, progressive collapse, possibly triggered by impact, blast, or fire, is another dangerous consequence to structures when in the absence of adequate robustness design. Due to varied performance demands, addressing both issues with consistent design solution can be challenging. This paper proposes a new multi-hazard protection concept utilizing iron-based shape memory alloy (Fe-SMA) components to improve both the robustness (against progressive collapse) and seismic resilience (against earthquake-induced LCF failure) of steel frames. Fe-SMA has emerged as a promising material in the field of civil engineering due to its unique thermal-induced shape recovery, superior low cycle fatigue (LCF) resistance, and outstanding ductility. In this paper, the angle form of Fe-SMA components is selected, serving as energy dissipation elements in steel beam-to-column connections which are crucial for ensuring structural safety/integrity against various hazards. Experimental investigations were conducted to understand the basic mechanical properties of Fe-SMA angles under monotonic tensile and LCF loading, followed by comprehensive numerical studies demonstrating the use of Fe-SMA angles for steel beam-to-column connections against cyclic loading as well as ‘column loss’. The results confirmed that Fe-SMA is capable of resisting cyclic loading with much improved LCF life, and meanwhile, offers significantly enhanced chord rotation capacity as well as maximum dynamic load resistance of beam-to-column connections against progressive collapse.

Abstract Su403: Iterative Simulation to Optimize Mechanical CPR Device Application

Mechanical chest compression devices (MCDs) are commonly used for in-hospital and emergency department (ED) cardiac arrest resuscitation. Manufacturer guidelines and educational materials demonstrate that in the prehospital setting, MCDs can be deployed with an interruption in CPR of less than 15 seconds. No similar materials exist for the in-hospital environment, where observational studies have noted median CPR interruptions of up to 40 seconds for MCD deployment. With the integration of extracorporeal CPR (eCPR) into OHCA systems of care, the need to transfer patients with ongoing CPR to MCDs in the ED is growing. To develop a hospital-specific procedure for receiving a patient in cardiac arrest and deploying the MCD with minimal no-flow time. We used an iterative participatory design process to develop a procedure for receiving patients in cardiac arrest from Emergency Medical Services (EMS). Tasks included transferring a patient, replacing defibrillator pads, and deploying the hospital MCD with minimal no-flow time. Participants including ED physicians, nurses, and respiratory therapists performed a series of simulations using a high-fidelity manikin, resuscitation equipment, and an MCD. Simulations were followed by focused debriefings, participant-directed modification of the working procedure, and repeat simulation until participants expressed satisfaction with the procedure. Participant roles were shuffled after each round. The primary outcome was the duration of CPR interruption required to deploy the MCD; change in this time over successive iterations was assessed using a Wilcoxon signed-rank test. The final procedure described a sequence of steps and responsibilities that participants deemed efficient and reproducible. Through seven simulation-debriefing cycles, CPR interruption associated with MCD deployment decreased from 19 to 10 seconds (p = 0.033). The most common failure modes that participants corrected during modifications involved needed equipment that was out of reach, obstructed provider positioning, and poorly defined roles. On subsequent days, two additional groups of on-shift ED providers deployed the MCD in less than 15 seconds following the developed procedure. Using an iterative design process, we created an MCD deployment procedure that minimized CPR interruptions and was acceptable to hospital staff. This represents an effective, low-cost methodology to design a process for transfer of care during CPR and MCD deployment.

A Review on Fatigue Characteristics of Nickel‐Aluminum Bronze (NAB): Conventionally Fabricated and Additively Manufactured

ABSTRACTNickel‐aluminum bronze (NAB) is extensively utilized across various industries, particularly marine applications due to its exceptional corrosion resistance. The mechanical properties of NAB are highly dynamic, and influenced by factors such as manufacturing processes, operating environments, and microstructure. This variability introduces complexities and challenges in addressing fatigue, the most common failure mode in metals. This review offers a thorough examination of the fatigue properties of NAB in both their conventionally fabricated and additively manufactured (AM) forms. This review explains the mechanisms that modulate fatigue in NAB by analyzing the existing literature and identifying critical factors such as microstructure, defects, and processing parameters. The goal is to improve the comprehension and dependability of NAB by contrasting the fatigue resistance of cast and AM NAB. The ultimate objective of this comprehensive examination is to predict and reduce component failures, thereby extending the service life and performance of NAB components in demanding environments.

Predicting fatigue crack initiation life in typical joints of offshore observation tower structures

ABSTRACT Tubular structures are widely used in steel constructions, such as offshore platforms, because of their superior mechanical qualities, efficient use of materials, lightweight and aesthetically pleasing appearance. The most common failure mode of offshore tubular joints is fatigue damage brought on by cyclic loading during the course of their service life, like wind, wave and equipment vibration. In this paper, the finite element model of the TK-type tubular joint at the stress concentration position is established by analyzing the load and response of the observation tower. The continuum damage mechanics method has been used to evaluate the fatigue crack initiation position and life of the tubular joint, and the crack initiation life of the key nodes has been predicted, which provides theoretical support for ensuring the service safety of the offshore observation tower.

A novel FMECA method for CNC machine tools based on D-GRA and data envelopment analysis

Failure Modes, Effects, and Criticality Analysis (FMECA) is a commonly used method for analyzing system reliability. It is frequently applied in identifying weak points in the reliability of CNC machine tools. However, traditional FMECA has issues such as vague descriptions of risk factors, equal treatment of risk factors, and unclear directions for improving weak points. In response to the issue of vague descriptions of risk factors, this paper further expands severity (S) into machine hazard (M) and personal hazard (P), and subdivides detectability (D) into functional structural complexity (D1) and detection cost (D2). In addressing the issue of treating risk factors equally, this paper integrates Distance Analysis Method (DAM) and Grey Relational Analysis (GRA) to propose Distance-Grey Relational Analysis (D-GRA). Subsequently, based on the D-GRA method, the weights of each risk factor were determined by comprehensively considering expert system scores and actual economic loss indicators. In response to the issue of unclear improvement directions for weak points, this paper introduces the BCC model. It treats common failure modes of CNC machine tools as decision-making units within the BCC model, refines risk factors as input indicators, and evaluates the efficiency values of each decision-making unit based on various actual losses as output indicators. Through efficiency value analysis, it proposes improvement directions for weak points. Then, based on the weights of risk factors and the efficiency values of failure modes, a modified calculation method for the new Risk Priority Number (RPN) is proposed to amend the traditional RPN, This paper takes the electric spindle system of a certain machining center as an example, applies the proposed method to rank common failure modes with the new RPN, and compares it with other RPN calculation methods to verify the rationality of the proposed approach. Finally, it presents improvement directions for reliability enhancement.

When Disaster Strikes: Conversion of Unicompartmental Knee Arthroplasty to Total Knee Arthroplasty

ObjectivesTo investigate the causes of failure in unicompartmental knee arthroplasty (UKA), types of implants used in the revision, evaluate the need to use tibial stems, metal block augmentations and bone grafts during conversion to total knee arthroplasty (TKA) MethodsIn a 10-year retrospective analysis, focusing on cases of UKA failure, our study aimed to categorize early and late failures, determine the primary failure modes, and assess the utilization of bone augmentations and grafts during conversion to TKA. We evaluated patient data, diagnoses, procedure intervals, and follow-up periods to provide a comprehensive understanding of the conversion process. ResultsDuring the past decade, 301 UKA procedures were performed, with 36 knees (11.96%) requiring conversion to TKA. Patient ages averaged 64.3 years, with varied diagnoses, including osteoarthritis and avascular necrosis. The most common failure mode was component loosening or sinking (52.78%), followed by progression of arthritis (25%). Of the 31 cases with mobile-bearing UKA, 9 (29.03%) developed instability and displacement of the polyethylene. Of the 36 cases converted from UKA to TKA, in 31 (86.11%) a revision tibial component with a tibial stem was used. Metal block augmentation was performed in 19 knees (52,78%). All revised UKAs were converted to cemented TKA, with a focus on addressing tibial side issues, which constituted 72.22% of the revisions. ConclusionThis study highlights the challenges associated with UKA failure, particularly early failures linked to displaced bearings. Converting from UKA to TKA presents technical hurdles, including rod alignment and utilization. Management of proximal tibial defects with metal block augmentation proves to be a viable approach. The use of modular metal augmentation simplifies the reconstruction process. Although the study has limitations, it contributes valuable information about the complexities of knee arthroplasty conversion. Level of evidenceTherapeutic study, level IV (case series).

Bond behavior between the deformed steel bar and different types of cementitious grout under reversed cyclic loading

To systematically investigate the bond behavior of deformed steel bars in cementitious grout, direct pullout tests were conducted on 15 sets of specimens by considering five types of cementitious matrixes and three different loading schemes. The failure modes, bond stress-slip curves, as well as the bond degradation and cumulative energy dissipation of specimens under reversed cyclic loading, were compared and analyzed. Results indicate that splitting pull-out or pull-out failure modes were observed, and pull-out failure was the most common failure mode of the specimen (accounting for 91 %) due to the installation of stirrups and the sufficiently short anchorage length. Meanwhile, regardless of the loading scheme, the general relationship between the magnitude of maximum bond stress of specimens composed of different cementitious materials was shown as C60＞CGM-270＞CGM-300＞CGM-340＞CGM-380, while there was no consistent pattern in relative slippage. Moreover, the relationship between the degradation of the maximum bond stress and stiffness of each specimen under reversed cyclic loading was shown as CGM-380 >CGM-340 ≈CGM-300 >CGM-270 >C60. The degradation mainly occurs in the first two cycles, and then gradually stabilizes. Furthermore, the cumulative energy dissipation relationship of specimens with different materials was shown as C60 >CGM-270 >CGM-300 >CGM-340 >CGM-380 under the reversed cyclic loading. The above investigations could provide theoretical support for the evaluation of ductility and energy dissipation of concrete members strengthened with cementitious grout under earthquake actions.

Engineered Tendon-Fibrocartilage-Bone Composite With Mechanical Stimulation for Augmentation of Rotator Cuff Repair: A Study Using an In Vivo Canine Model With a 6-Month Follow-up

Background: Rotator cuff repair augmentation using biological materials has become popular in clinical practice to reduce the high retear rates associated with traditional repair techniques. Tissue engineering approaches, such as engineered tendon-fibrocartilage-bone composite (TFBC), have shown promise in enhancing the biological healing of rotator cuff tears in animals. However, previous studies have provided limited long-term data on TFBC repair outcomes. The effect of mechanical stimulation on TFBC has not been explored extensively. Purpose: To evaluate functional outcomes after rotator cuff repair with engineered TFBC subjected to mechanical stimulation in a 6-month follow-up using a canine in vivo model. Study Design: Controlled laboratory study. Methods: A total of 40 canines with an acute infraspinatus (ISP) tendon transection model were randomly allocated to 4 groups (n =10): (1) unilateral ISP tendon undergoing suture repair only (control surgery); (2) augmentation with engineered TFBC alone (TFBC); (3) augmentation with engineered TFBC and bone marrow-derived stem cells (BMSCs) (TFBC+C); and (4) augmentation with engineered TFBC and BMSCs, as well as mechanical stimulation (TFBC+C+M). Outcome measures—including biomechanical evaluations such as failure strength, stiffness, failure mode, gross appearance, ISP tendon and muscle morphological assessment, and histological analysis—were performed 6 months after surgery. Results: As shown in the mechanical test, the TFBC+C+M group exhibited higher failure strength compared with other repair techniques. The most common failure mode was avulsion fracture in the TFBC+C+M group, but tendon-bone junction rupture was observed predominantly in different groups. Engineered TFBC with mechanical stimulation showed over 70% relative failure strength compared with normal ISP, and the other groups showed about 50% relative failure strength. Histological analysis revealed less fat infiltration and closer-to-normal muscle fiber structure in the mechanical stimulation group. Conclusion: This study provides evidence that mechanical stimulation of engineered TFBC promotes rotator cuff regeneration, thus supporting its potential for rotator cuff repair augmentation. Clinical Relevance: This study provides valuable evidence supporting the use of a novel tissue-engineered material (TFBC) in rotator cuff repair and paves the way for advancements in the field of rotator cuff regeneration.

Coupling Fault Diagnosis of Bearings Based on Hypergraph Neural Network.

Coupling faults that simultaneously occur during the operation of mechanical equipment are widespread. These faults encompass a diverse range of high-order coupling relationships, involving multiple base fault types. Based on the advantages of hypergraphs for higher-order relationship descriptions, two coupling fault diagnosis architectures based on the hypergraph neural network are proposed in this paper: 1. In the coupling fault diagnosis framework based on feature generation, the base faults serve as the hypergraph nodes, and each hyperedge connects the base faults. The generator, which consists of the hypergraph neural network, generates coupling faults as negative samples to enforce regularization constraints for the discriminator training. 2. In the coupling fault diagnosis framework based on feature extraction, each node represents a fault mode, and each hyperedge connects nodes with common failure modes. The multi-head attention mechanism extracts the features of base faults, and the common fault features in a hyperedge are aggregated via the hypergraph neural network. The inner product correlation is used to diagnose the fault modes. The results show that the diagnostic accuracy for coupling faults with the two frameworks reaches 88.6% and 86.76%, respectively. Both frameworks can be used for the diagnosis and analysis of high-order coupling faults.

Development of the neutral gas diagnostic system for neutral pressure measurements and gas analysis on the SPARC tokamak.

A suite of plasma diagnostics will be installed on the SPARC tokamak to allow for real-time plasma control, an investigation of high-field tokamak physics, and to de-risk the design of ARC, a compact fusion power plant with the aim to supply electricity to the grid. Among these diagnostics is the neutral gas diagnostics system (NTGS), a set of pressure sensors and gas analyzers used to monitor neutral pressure and gas composition for plasma control, optimization of wall conditioning, and helium ash removal, among other measurement functions linked to operational and scientific research needs. While reliable measurements of neutral pressure and gas composition have been fielded on existing magnetic-confinement fusion devices, SPARC represents a step increase in challenge due to its larger power density, higher field, high vacuum vessel bake temperatures, and higher neutron flux environment, as well as a step decrease in the accessibility for maintenance of in-vessel sensors. Multiple sensor types will be employed to have defense-in-depth and mitigate common failure modes. The NTGS system is currently progressing through final design, working to close out decisions using prototyping and analysis, and then moving on to procuring sensors for assembly and installation on SPARC. This paper outlines the current status of the system design and the diagnostic requirements that motivate neutral gas measurements on SPARC, as well as highlights the planned prototyping activities.

An efficient isogeometric buckling optimization framework for multi-patch laminated shells: Leveraging 3D solid elements, lamination parameters and penalty method

Buckling is a common failure mode of laminated shell structures during service, and isogeometric analysis methods are highly suitable for the buckling analysis due to their accurate geometric modeling capability and high-order continuity. However, the isogeometric buckling analysis for a multi-patch structure and its optimal design still face challenges in computational efficiency. To address this issue, this paper proposes an integrated framework for the buckling optimization of multi-patch laminated shells, which leverages 3D solid elements, lamination parameters, and the penalty coupling method. Solid-shell elements have advantages in shell analysis due to their simplicity, absence of rotational degrees of freedom, and adaptive layering in the thickness direction. Lamination parameters simplify the optimization of fiber orientations in laminated shells by condensing the design variable space and improving the convexity of the optimization problem. The penalty method can handle the coupling in multiple patches at a relatively low cost. Nevertheless, lamination parameters are rarely applied to the case of solid-shell elements. In addition, despite using lamination parameters, the number of design variables for multi-patch structures remains significantly large. To tackle these issues, this study derives the solid-shell formulation in lamination parameters and the sensitivity analysis formulae in the reverse mode. Experiment validation is conducted to assess the accuracy of the proposed method based on lamination parameters with solid elements, the feasibility of the multi-patch optimization model, and the computational efficiency of optimization sensitivity based on the reverse mode compared to the forward counterpart common in the literature.

Patterns of treatment failure in patients with sinonasal squamous cell carcinoma after chemoradiotherapy.

To investigate the failure patterns based on precision radiation treatment and to determine the predictive factors of treatment failure for sinonasal squamous cell carcinoma (SNSCC) patients. This was a retrospective study that included 214 cases of treatment failure from 441 consecutive patients. Two experienced radiation oncologists evaluated the tumour volume of cases with local recurrence. The 5-year overall survival (OS), progression-free survival (PFS) rates, and distant-metastasis-free survival (DMFS) were estimated. Investigations were performed on the factors that predicted local failure or distant metastasis. About 140 (31.7%) patients developed local recurrence, 24 (5.4%) experienced regional failure, and 65 (14.7%) underwent distant metastasis. In-field, marginal, and out-of-field failures occurred in 55.7% (78/140), 33.6% (47/140), and 10.7% (15/140) of patients with local recurrence, respectively. In logistic regression analysis, factors statistically significant for total local failure included treatment mode (P < .01), chemotherapy (P < .01), and surgical margins (P < .01). Primary tumours with poor differentiation (P = .018) and R2 resection margin (P = .009) were more prone to develop distant failure. The 5-year OS, PFS, and DMFS rates were 57.8%, 52.0%, and 56.7% for the whole cohort. In univariate and multivariate analysis, the skull base involvement was an independent predictor for poorer OS and PFS; orbital invasion was an independent predictor for poorer OS. Local recurrence and distant metastasis were the most common failure modes. Treatment mode, chemotherapy, and surgical margins were related to local recurrence. Poor differentiation and R2 resection margin were predictors for distant failure. Local recurrence is the most common failure pattern in patients with SNSCC who accepted chemoradiotherapy, and marginal and out-of-field failures occurred in 44.3% of patients with local recurrence.

Influence of bolt preload of anchors on bond-slip behavior of fiber fabric-steel interface

Bond-slip behavior is a common failure mode in steel structures reinforced with fiber fabric. Premature debonding of the fiber fabric significantly impacts the effectiveness of steel structure reinforcement. In this study, a gripping anchor is proposed to enhance the reliability of the interface between fiber fabric and steel plates. Experimental investigations were conducted to analyze the influence of anchor bolt preload on the double shear joint between fiber fabric and steel plates. 41 specimens were prepared and tested to explore the effects of parameters such as bolt preload, anchor position, number and type of fiber fabric layers, and bond length on load-bearing capacity. Comparative analyses were conducted on failure modes, ultimate loads, and stress-strain distributions of the specimens. Experimental results indicate that the position of the anchor has a minimal impact on the ultimate bearing capacity of the specimen. However, anchors positioned closer to the joint end exhibit lower ductility upon failure. A novel predictive model was developed to characterize the bond-slip behavior of preload applied to carbon fiber fabric and steel plates. The theoretical model of the ultimate bearing capacity in the yield stage fits well with the experimental results of specimens with three layers of carbon fiber fabric, with a difference range of 0.34 % to 14.97 % compared to actual results. This indicates that the model has high accuracy in predicting stress-strain and bearing capacity.

Evaluation and analysis of abrasive wear resistance of hybrid roller bearings under lubricant contamination

Abrasive wear is a common failure mode of rolling bearings. To enhance the resistance of traditional all-steel bearings to abrasive wear, the structure of traditional all-steel cylindrical thrust roller bearings has been appropriately adjusted, and hybrid roller bearings have been formed by replacing some of the steel rollers in the traditional bearings with ceramic rollers. The frictional performance of hybrid roller bearings under lubricant contamination conditions was analyzed, and the wear reduction mechanism was discussed. The results show that under the condition of lubricant contamination, replacing the appropriate amount of ceramic rollers not only helps reduce friction and decrease wear but also contributes to improving the overall temperature rise of the bearing. Furthermore, when the total amount of contaminants is constant, a specific threshold exists for the impact of replacing the number of rolling elements on reducing mass loss. For a substantial reduction in wear with hybrid roller bearings, the replacement rollers should constitute at least one-fifth of the total number of rollers. The wear reduction observed in hybrid roller bearings results from a combination of crushing and refinement, grinding and finishing, and self-healing mechanisms.

Use of Fast-Setting Bone Graft Substitute to Allow Single-Stage Revision Anterior Cruciate Ligament Reconstruction

Background: The overall revision rate for primary anterior cruciate ligament reconstruction (ACLR) has increased over the past decade, with the commonest mode of failure being a combination of traumatic, technical, and biological factors. The challenge in revision ACLR is the need to address malpositioned or widened tunnels with the ideal scenario being single-stage revision, with widened and type 2 tunnels being the most difficult scenarios to deal with. Tunnels can be filled using autograft, allograft, and more recently described bone graft substitute (BGS). In this video, we describe a technique using fast-setting BGS to fill the problem of malpositioned tunnel or tunnels to allow single-stage revision ACLR. Indications: This technique is indicated in patients undergoing revision ACLR where tunnels are nearly right (type 2) with no widening at the joint surface aperture. Technique Description: Following preparation of the notch, the femoral tunnels are prepared in the normal fashion to remove all the previous graft and to create fresh bleeding surfaces. The fluid in the knee is completely drained, and the femoral tunnel is repeatedly dried with ribbon gauze that is left in place until ready to inject. The BGS, genex (Biocomposites Ltd), is mixed and loaded into the delivery syringe before injecting arthroscopically. After 15 minutes, the new anatomic femoral tunnel is then prepared in routine fashion. The same steps are repeated for the tibial tunnel. Results: Twenty patients underwent single-stage revision ACLR using this technique. There have been no reruptures in this series. All eligible patients at the 12-month follow-up had grade 0 or 1 laxity on clinical examination and full incorporation of the BGS on radiographs. There were no complications related to the BGS during the intra- or postoperative period. Discussion/Conclusion: We describe a technique that allows revision ACLR to be performed as single stage in a subset of patients with type 2 tunnels with successful short- to mid-term results. We have found this to be a safe and effective way to avoid 2-stage surgery in a subgroup of cases who have a challenging problem for surgeons to manage. Patient Consent Disclosure Statement: The author(s) attests that consent has been obtained from any patient(s) appearing in this publication. If the individual may be identifiable, the author(s) has included a statement of release or other written form of approval from the patient(s) with this submission for publication.

Glenoid component cyclical failure decreases with increasing baseplate contact: a biomechanical study

BackgroundGlenoid baseplate loosening remains a common mode of failure in reverse shoulder arthroplasty. One of the key factors to baseplate stability is theorized to be maximization of baseplate backside contact. The purpose of this biomechanical study is to investigate the role of varying degrees of backside bony glenoid support in component stability for reverse total shoulder arthroplasty. MethodsTwenty synthetic scapular models were divided into 3 test groups of 5 scapulae with glenoid baseplate contacts of 40%, 60%, and 75%, and one control group with glenoid baseplate contact of 100%. Standardized application of a commercially available glenoid baseplate and glenosphere was performed. The scapulae were mounted on a linear bearing with a humeral component and polyethylene liner which were affixed to a biaxial servohydraulic fatigue testing system. Each specimen was loaded for 10,000 cycles or to failure, about a 55° arc along the glenosphere at a rate of 1 Hz as a 750 N compression load was applied. Failure was defined as fracture of the scapula with implant fixation compromise. Before and after loading, stability of the baseplate was assessed by quantifying the total motion between the model and the baseplate with digital calipers as a ramp load between 0 and 150 N was applied. Two-sample unpaired t-tests were performed with significance set at P < .05. ResultsBaseplate contacts of 40% (1623 ± 227, P = .0001), 60% (3299 ± 1170, P = .0001), and 75% (5615 ± 1587, P = .0077) demonstrated statistically significant decrease in the average number of cycles to failure in all cohorts compared to our control (8641 ± 1070). Cycles taken for initial cracks to progress to failure showed no significant differences; 40% contact (862 ± 452, P = .4751), 60% contact (1651 ± 996, P = .4318), 75% contact (2882 ± 1347, P = .0620), and 100% control (1166 ± 657). Baseplate contacts of 40% (6150.4 ± 444.0, P = .0006), 60% (4647.1 ± 552.3, P = .0072), and 75% (2927.8 ± 918.5, P = .2573) demonstrated increasing micromotion (pre-post cyclical loading) in all cohorts compared to our control (2074.7 ± 1164.6) with statistical significance at 40% and 60%. ConclusionThese biomechanical tests demonstrate that decreasing glenoid baseplate backside contact leads to increased micromotion and fewer cycles to failure. This supports the surgical goal of achieving maximal glenoid baseplate backside contact, suggesting that decreased glenoid baseplate support could contribute to significant loosening.

MR-conditionality failure modes: a comparison across various spinal cord stimulators.

As spinal cord stimulation (SCS) becomes a staple of chronic pain management, the SCS industry must constantly evolve to ensure safety, convenience and enhanced efficacy. Beyond waveforms and size, MR-conditionality is a key differentiator sought out by physicians and patients when choosing SCS devices. Many common SCS complications, including lead migration, can affect the MR-conditionality. The authors reviewed literature published between 2015 and 2024 using PubMed and Google Scholar databases, as well as USFDA labels for magnetic resonance imaging and technical manuals with further confirmation from local representatives. Through extensive review of the literature and direct extraction from each SCS device company, the authors aimed to investigate the specific terms of MR-conditionality under various circumstances. This article provides a collective reference of the MR-conditionality of the currently available SCS devices under normal conditions, as well as with common failure modes, such as lead migration, lead fracture and battery detachment.

Study of synergistic and competitive mechanisms on toughening CFRP composites with intrinsic and extrinsic multiscale interleaves

Delamination damage is a common failure mode of carbon fiber reinforced polymer (CFRP) laminates, which severely limits their application. This paper proposes a novel interlaminar toughening structure based on intrinsic and extrinsic multiscale toughening mechanisms using nanoscale multi-walled carbon nanotubes (MWCNTs) and microscale core-shell rubber (CSR). The resin sample M-0.5/C-8, containing 0.5 wt% MWCNTs and 8 wt% CSR, exhibited significant improvements in fracture toughness, with increases of 183.3 % in the mode-I critical stress intensity factor (KIC, Resin) and 412.0 % in the critical energy release rate of resin (GIC, Resin). However, its flexural strength and modulus decreased by 3.1 % and 3.3 %, respectively. Introducing MWCNTs and CSR into the interlayers of the CFRP, the interleaved toughened CFRP laminate exhibited a 123.3 % improvement in the mode-I critical energy release rate (GIC, Comp) and a 79.6 % increase in the mode-II critical energy release rate (GIIC, Comp) during the crack propagation stage, without sacrificing flexural performance. This remarkable enhancement in interlaminar fracture toughness results from the simultaneous triggering of nanoscale extrinsic toughening and microscale intrinsic toughening during crack growth. The flexural properties and fracture toughness of Epoxy/MWCNTs/CSR composites were also investigated to understand the properties transformation from resin matrix to CFRP. Morphological characterization and numerical analysis were used to analyze the synergies and constraints between two energy dissipation behaviors.

Fatigue crack propagation life analysis of propeller

Fatigue crack fracture is a common failure mode in structures. For the propeller with initial crack, the hydrodynamic effect cannot be ignored when studying the fatigue crack propagation behavior. Taking the full-size KP505 propeller as the research object, its hydrodynamic performance is simulated and verified. By using the fluid-structure interaction (FSI), the pressure distribution and stress distribution of propeller under different working conditions are analyzed comprehensively, and the position of propeller hot spot stress is obtained. According to the principal stress and its direction of the hot spot stress, the location and orientation of possible macroscopic crack initiation are determined. By using the linear elastic fracture mechanics and finite element method (FEM), the propeller fatigue crack propagation law and life are calculated. The analysis results show that the Forman-Newman-de Koning (FNK) model predicts more complete fatigue crack propagation life than Paris model. The fatigue crack propagation of propeller has two stages, steady propagation stage, and accelerated propagation stage. The crack breaking blade thickness is the dividing point between the two stages. In addition, the effects of the advance coefficient, stress ratio, and initial crack size on the computed results are also analyzed, which provide reference for ship driving and propeller maintenance.