Early Failure Mechanisms Research Articles

Corrosion fatigue analysis of suspenders on continuous suspension bridge under combined action of wind and traffic

Suspenders and displacement-controlled device (DCD) are crucial force transmission components connecting the girder and the main cable in the continuous suspension bridge. These two structures will be subjected to environmental corrosion and fatigue loading simultaneously after the protection system fails. To investigate the safety of structure during the service, a comprehensive framework for corrosion fatigue analysis of continuous suspension bridge under the combined effects of wind and traffic flow was proposed. Taking a three-span continuous suspension bridge with DCD as engineering background, the wind-traffic combined load model was established and the fatigue life of the corroded suspenders was examined. Based on the Multilayer Perceptron algorithm, the impact of load form, environmental grade and DCD type on the corrosion fatigue performance of suspenders was analyzed. The results indicate that the fatigue life of suspender is significantly reduced due to uniform and pitting corrosion of the internal steel wires. The early failure mechanism of suspender is extremely sensitive to corrosion factors. Traffic load is the primary cause of fatigue damage to suspenders. Setting up DCD is beneficial for improving the corrosion fatigue life of the suspenders, and the selection of DCD type mainly depends on the topographical factors of the bridge site.

Li-Ion Cell in Operando Monitoring and Prognostication Using CMUT Devices

Capacitive micromachined ultrasonic transducer (CMUT) devices are ideal solutions for in operando battery monitoring applications especially for consumer electronics. Their minute size (2mm x 1mm x 0.5mm) allows direct placement on the battery without affecting the form factor of the device, the volume production techniques used for their manufacture allow for a very low-cost device, and they can be easily integrated with front-end integrated circuits either in a single device or in a discrete multichip form. Together with industry partners we have developed CMUT devices that we use to continuously monitor the behavior of a battery while it is cycling.For this work we used CMUTs (close-up shown in Fig. 1(a)) developed to operate with a low bias voltage (less than 30 V) which reduces the complexity of the driving hardware. The impulse response and its frequency content are shown in Fig. 1(b). In collapse mode, the peak frequency is 4.0 MHz and the one-way –3 dB BW is 76%, which allows flexibility in setting the drive conditions to interrogate the battery. Our testing also shows that the CMUTs show good device-to-device uniformity and they have a very stable performance in variable temperature environments (e.g. 0℃ - 60℃ ).The cell is interrogated in pulse-echo mode. The CMUT is excited by a wide-band unipolar pulse and the returned analog signal is filtered and amplified. The signal is then digitized and processed to extract features that allow us to quantify the state of the battery. Figure 1(c) depicts such signal features change under baseline cell cycling conditions (three cycles at a charge rate of C/4). These changes are the result of mechanical material property changes in the cell e.g., electrode stiffness and density [1] which directly affect the acoustic wave propagation inside the cell. Figure 1(d) depicts signal feature change due cell overcharge (red line). Ultrasound is especially sensitive to gas generation which occurs as the cell voltage extends beyond normal operating range [2]. Signal features provide early warning notice that cell is outside of normal operating conditions.Figure 1. a) Close-up image of CMUT device. b) CMUT impulse response and corresponding frequency content. c) Signal features (RMS and Time of Flight (ToF)) and thickness change during C/4 charge and discharge. d) Signal features during cell constant current overcharge. Cell overcharged after 4.4V (red line). Chang, W. et al. Measuring effective stiffness of Li-ion batteries via acoustic signal processing. Mater. Chem. A 8, 16624–16635 (2020).Appleberry, M. C. et al. Avoiding thermal runaway in lithium-ion batteries using ultrasound detection of early failure mechanisms. Journal of Power Sources 535, 231423 (2022). Figure 1

Study on Fatigue Characteristics of Rivets in Bearing Cage for an Aeroengine Transmission System

This study focuses on the rivet early fatigue characteristics in a deep-groove ball bearing cage for a transmission system in a turboprop engine. Nonlinear dynamic differential equations for the deep-groove ball bearing with a two-piece cage were developed. The rivet stress was used to identify the early failure mechanism of the rivets. This investigation revealed that by delivering an optimal preload of the rivet causes the two halves of the cage have less misalignment and a lower rivet stress. The fit relationship between the rivet and the rivet bore has a significant influence on the rivet stress. Excessive clearance increases the stress on the head of the rivet, while excessive interference increases the stress on the middle of the rivet. For the 1.5 mm diameter rivet analyzed in this study, the appropriate fit relationship is −0.02 mm–0 mm. A reasonable matching value of the load and the speed and the cage clearance ratio are beneficial to reducing the rivet stress. The impact load acting on the bearing and a ring misalignment can increase the rivet stress.

Graft thrombosis after coronary artery bypass surgery and current practice for prevention.

Coronary artery bypass grafting (CABG) is the most frequently performed cardiac surgery worldwide. The reported incidence of graft failure ranges between 10% and 50%, depending upon the type of conduit used. Thrombosis is the predominant mechanism of early graft failure, occurring in both arterial and vein grafts. Significant advances have been made in the field of antithrombotic therapy since the introduction of aspirin, which is regarded as the cornerstone of antithrombotic therapy for prevention of graft thrombosis. Convincing evidence now exists that dual antiplatelet therapy (DAPT), consisting of aspirin and a potent oral P2Y12 inhibitor, effectively reduces the incidence of graft failure. However, this is achieved at the expense of an increase in clinically important bleeding, underscoring the importance of balancing thrombotic risk and bleeding risk when considering antithrombotic therapy after CABG. In contrast, anticoagulant therapy has proved ineffective at reducing the occurrence of graft thrombosis, pointing to platelet aggregation as the key driver of graft thrombosis. We provide a comprehensive review of current practice for prevention of graft thrombosis and discuss potential future concepts for antithrombotic therapy including P2Y12 inhibitor monotherapy and short-term DAPT.

Reoperation after early and late failure of mitral valve repair for degenerative disease

ObjectivesTo determine mechanisms of early and late failure after mitral valve repair for degenerative disease, identify factors associated with re-repair, and evaluate durability of re-repair. MethodsFrom January 2008 to July 2020, 330 reoperations were performed for recurrent mitral valve dysfunction after initial valve repair for degenerative disease. Mechanisms of repair failure were determined by review of preoperative imaging and operative reports. Multivariable analysis was performed to identify factors associated with likelihood of re-repair or replacement. Durability of re-repair was assessed using longitudinal analysis of postoperative echo data. ResultsEighty-five of 330 (26%) reoperations were performed for early repair failure within 1 year and 245/330 (74%) for late failure thereafter. Suture/annuloplasty dehiscence, systolic anterior motion, hemolysis, and ventricular remodeling were more common mechanisms of early failure and disease progression and fibrosis late failure. Forty percent (34/85) of early failures were re-repaired versus 24% (59/245) of late failures. Re-repair was more common than replacement in recent years and was associated with earlier reoperation (median 1.5 vs 3.9 years; P = .0001). No in-hospital deaths occurred after re-repair; 2 patients (0.8%) died after valve replacement. Freedom from severe mitral regurgitation after re-repair was 93% at 7 years. ConclusionsMitral valve re-repair can be performed with low rates of mortality and morbidity for early and late valve dysfunction. Mechanisms of early repair failure differ from those of late failure and are generally more amenable to re-repair. In selected patients who present after failed repair, we prefer mitral re-repair to valve replacement whenever technically feasible.

Avoiding thermal runaway in lithium-ion batteries using ultrasound detection of early failure mechanisms

Thermal runaway leading to catastrophic failure has slowed the adoption of lithium-ion batteries, highlighting the need for early warning systems. In this work, ultrasound is used to detect physical changes in 0.950 Ah Li-ion battery cells by inducing conditions associated with thermal runaway. Ultrasound signal features are extracted as the batteries are cycled under baseline conditions and subsequently subjected to constant current and voltage overcharges. Two conditions identifying failure are defined: a warning to detect the start of overcharge and an emergency stop (E-stop), to immediately take the battery out of service. Using changes in ultrasound signal features, consistent warning and stopping classifications are applied to all failure experiments. On average, a warning notification was issued after 15% of the overcharge time, and an E-stop was triggered after 35% of total overcharge duration before failure. Further testing suggests it is possible to avoid thermal runaway by reacting to intermediate, warning notifications prior to an immediate E-stop. In other words, not only can detection derived by ultrasound identify battery failure before a catastrophic event, but can also provide early, actionable warnings so that overcharges can be detected and corrected quickly enough so the battery does not need to be decommissioned.

Modes of failure of Trifecta aortic valve prosthesis.

OBJECTIVESSeveral concerns have been recently raised regarding the durability of Trifecta prostheses. Different mechanisms of early failure were reported. Our aim was to study in a large population the modes of failure of Trifecta valves.METHODSWe conducted a retrospective analysis of patients who underwent surgical aortic valve replacement with a Trifecta prosthesis during the period 2010–2018. Details regarding the mode of failure and haemodynamic dysfunction were collected for patients who underwent reintervention for structural valve failure. The Kaplan–Meier method was used to calculate survival. Competing risk analysis was performed to calculate the cumulative risk of reintervention for structural valve failure.RESULTSThe overall population comprises 1228 patients (1084 TF model and 144 TFGT model). Forty-four patients—mean patients’ age at the time of the first implant 69 (standard deviation: 12) years and 61% female—underwent reintervention for structural valve failure after a median time of 63 [44–74] months. The cumulative incidence of reintervention for structural valve failure was 0.16% (SE 0.11%), 1.77% (SE 0.38%) and 5.11% (SE 0.98%) at 1, 5 and 9 years, respectively. In 24/44 patients (55%), a leaflet tear with dehiscence at the commissure level was found intraoperatively or described by imaging assessment. The cumulative incidence of reintervention for failure due to leaflet(s) tear was 0.16% (SE 0.11%), 1.08% (SE 0.29%) and 3.03% (SE 0.88%) at 1, 5 and 9 years, respectively.CONCLUSIONSLeaflet(s) tear with dehiscence along the stent post was the main mode of early failure, up to 5 years, after Trifecta valves’ implantation.

Fracture analysis of Pre-cracked 8YSZ TBCs with edge and internal cracks under Thermo-mechanical load: A numerical approach

The thermal barrier coatings (TBCs) are used for hot component sections of gas turbines and aero-engines. The paper presents the effect of thermo-mechanical on the pre-cracked TBCs to analyze fracture parameters using the FEM method. The TBC model is considered with edge and internal cracks with different crack configurations such as crack length and cracks position between ceramic top coat and bond coat to find the strain energy release rate (SERR) and stress intensity factor (SIF). The TBC mixed-mode I/II fracture criterion is established. The numerical results showed that the crack tip field is shear dominant under thermo-mechanical loading irrespective of different crack configurations. The edge crack's SERR and SIF mode I/II are more significant than the internal crack, resulting in delamination. The long edge crack showed crack driving force of 2.13 J/m2 at P1 position, whereas the shift in crack position till P7 reduces the SERR to 1.48 J/m2. The internal crack at P1 showed the SERR of 0.91 J/m2 which reduces to 0.85 J/m2 at position P7. The edge crack resulted in a high amount of shear stress which is caused due to large opening of crack faces. In all crack configurations, the increase in crack length showed an increase in crack driving force and large opening of crack faces due to high shear stress. Also, the crack positioned in the ceramic topcoat showed a high value of crack driving force, resulting in more probability of surface rupture followed by crack positioned at the interface of the topcoat/bond coat and crack positioned in the bond coat. The interface crack showed a high crack driving force compared to crack located near the interface due to bi-material and geometry discontinuity, resulting in stress intensification. The edge crack showed a high value of SIF mode I in the range of 0.1 to 0.35 MPa.m1/2 compared to internal crack which shows in the range of 0.05 to 0.18 MPa.m1/2. The edge crack shows high value of SIF mode II in the range of −0.05 to −0.22 MPa.m1/2 compared to internal cracks showing upto −0.1 MPa.m1/2. The crack length and position play an important role in crack initiation and propagation. The TBC structure with edge crack appears unstable and more likely to damage than internal crack, leading to an early failure mechanism.

Contact fatigue life prediction of rolling bearing considering machined surface integrity

PurposeRolling bearings often cause engineering accidents due to early fatigue failure. The study of early fatigue failure mechanism and fatigue life prediction does not consider the integrity of the bearing surface. The purpose of this paper is to find new rolling contact fatigue (RCF) life model of rolling bearing.Design/methodology/approachAn elastic-plastic finite element (FE) fatigue damage accumulation model based on continuous damage mechanics is established. Surface roughness, surface residual stress and surface hardness of bearing rollers are considered. The fatigue damage and cumulative plastic strain during RCF process are obtained. Mechanism of early fatigue failure of the bearing is studied. RCF life of the bearing under different surface roughness, hardness and residual stress is predicted.FindingsTo obtain a more accurate calculation result of bearing fatigue life, the bearing surface integrity parameters should be considered and the elastic-plastic FE fatigue damage accumulation model should be used. There exist the optimal surface parameters corresponding to the maximum RCF life.Originality/valueThe elastic-plastic FE fatigue damage accumulation model can be used to obtain the optimized surface integrity parameters in the design stage of bearing and is helpful for promote the development of RCF theory of rolling bearing.

Early failure mechanism research of electromechanical product based on meta-action

Early failure is the key factor that restricts the improvement of electromechanical product reliability. The research on early failure mechanism of electromechanical product can provide a basis for the subsequent failure cause tracing and failure diagnosis. At present, there are few systematic studies on the early failure mechanism of electromechanical product, which have the following shortcomings: firstly, the failure analysis objects in traditional failure methods cannot reflect the characteristic of electromechanical product that “motion determination electromechanical product function”; secondly, traditional failure analysis methods ignore the fact that mechanical and electronic systems are different in failure cause, failure mode and failure mechanism; thirdly, failure cause and failure mode are easily confused in traditional methods; finally, most of the traditional methods are qualitative analysis, which cannot directly show the generation process of failure. To address those problems, meta-action and meta-action unit of electromechanical product are selected as the analysis object herein. Early failure mode, early failure cause, and early failure mechanism of electromechanical product are defined and analyzed. A meta-action early failure mechanism quantitative analysis model considering electromechanical coupling is built, and the influence of failure cause on failure mode is analyzed. A CNC (computer numerical control) machine tool made in China is taken as an example. The results verify the applicability and correctness of the proposed method.

Connections in mixed structures with steel columns with threaded rods and normal strength concrete beams: Numerical analysis with incremental load

ABSTRACTThis research proposes to evaluate the suitability of a new type of hybrid or mixed joint for framed structures that are composed of H shape vertical elements made of structural steel and reinforced concrete with rectangular section horizontal elements. Researchers of Spanish origin have made the first experimental campaigns of these mixed joints using stud connectors welded to the flanges of the structural steel, which implies a follow‐up to the welding procedure. These researchers have concluded that these joints offer good resistance to static loading and that the contribution of strength by adherence and friction between the steel column and the concrete beam is important. In the framework of this research, relevant laboratory tests (cyclic load tests) will be carried out to evaluate and characterize the behavior of the joint in the event of seismic events, for areas of high seismic hazard, in addition, the modeling of the joint using the Finite Elements Method and the theory of mixtures of composite materials that anticipates their mechanism of failure. The innovative components of this research are the implementation of threaded rods, which will cross the flanges of the steel column and the evaluation of this joint under cyclic loading. This article will present and analyze the results of the first stage of this investigation, in which two partial models of the mixed joint with static load were made, which was applied at the end of each of the beams until producing its mechanism of failure. The results show an early failure mechanism on the outside contact surface between the two materials and deformations in the column outside the area embedded by the concrete.

An Integrated Model of Eliminating Early Failures for NC Machine Tools: A Case Study

A fundamental tenet of reliability theory is that the hazard function during NC machine tool’s life cycle displays a bathtub curve, and the curve can be viewed as comprised of early failure period, random failure period and wear-out period. To eliminate the early failures and improve the reliability of NC machine tools, this paper proposes the model and steps of eliminating early failures for NC machine tool. Firstly, Weibull two-fold mixture model is chosen to establish the bathtub curve model of NC machine tool, and division between early failure period and random failure period is identified. Secondly, the formation of early failure period and mechanism of early failures elimination are studied, and an integrated model of eliminating early failures for NC machine tool is established with reliability design and analysis domain, reliability test domain and early failures elimination domain. Finally, an example of rotary table in NC machine tool is shown to illustrate the applicability and validity of the model.

Optimizing follow-up after anatomic total shoulder arthroplasty

With increases in both total shoulder arthroplasty (TSA) volumes and patient life expectancies, the number of patients requiring follow-up after shoulder arthroplasty continues to grow exponentially. The purpose of this study is to establish a data-based follow-up schedule minimizing unnecessary patient and health care system costs without sacrificing patient care. Between January 1975 and January 2013, 2786 consecutive anatomic TSAs were performed at our institution. All shoulders undergoing reoperation/revision were reviewed to identify the common modes of failure and times to failure. A total of 208 shoulders (7.5%) required reoperation. Early failure mechanisms included instability, rotator cuff tears, and infection, with 63% of these reoperations occurring within 2 years. Later failures included mechanical failures (including component loosening) and periprosthetic fractures, with no identifiable peak occurrence. After 2 years, TSA failed at an average rate 1.1% per year. TSA failure after 2 years is uncommon and triggers surgical intervention in approximately 1% of patients per year. Routine in-person surveillance of all patients on a scheduled basis may not be necessary and would increase patient and other health care costs. We recommend in-person visits to assess healing, direct rehabilitation, and manage soft tissue or infectious issues until 2 years, with planned, periodic patient contact by mail and radiographic evaluation of patients with poor or worsening outcomes thereafter, unless patient concerns arise or a newer implant design warrants closer clinical assessment.

Coagulation, Fibrinolysis and Inhibitors in Failing Filters during Continuous Venovenous Hemofiltration in Critically Ill Patients with Acute Kidney Injury: Effect of Anticoagulation Modalities

Introduction: The mechanisms of early filter failure and clotting with different anticoagulation modalities during continuous venovenous hemofiltration (CVVH) are largely unknown. Methods: Citrate, heparin and no anticoagulation were compared. Blood was drawn pre- and post filter up to 720 min. Concentrations of the thrombin-antithrombin (TAT), activated protein C-protein C inhibitor (APC-PCI), and type I plasminogen activator inhibitor (PAI-1) were determined. Results: In case of early filter failure (<24 h), inlet concentrations of TAT and APC-PCI were higher over time, irrespective of anticoagulation. There was more production of APC-PCI and platelet-derived PAI-1 in the filter after 10 min in the heparin group than in other groups. In clotting filters, production of APC-PCI and PAI was also higher with heparin than citrate. Conclusion: Coagulation activation in plasma and inhibition of anticoagulation in plasma and filter may partly determine early CVVH filter failure due to clotting, particularly when heparin is used. Regional anticoagulation by citrate circumvents the inhibition of anticoagulation and fibrinolysis by platelet activation following heparin.

Metallization Reliability and Defectivity in Compound Semiconductors

Compound semiconductor devices are in mass volume production yet our understanding of reliability and defectivity of III-V materials is still evolving. Process-induced defects in electroplated Au interconnect metallization on GaAs devices were detected during the course of reliability testing. Abnormally high lognormal sigmas (σ > 0.7) indicated the existence of a bi-modal failure mechanism. A distinct early lifetime failure mode was observed along with the intrinsic electromigration metallization wear-out failure mode. Increased temperature stress showed only a slight acceleration on the early failure mechanism but selection of a higher resistance degradation failure percentage criterion reduced the extent of these early failures. Physical characterization of the electroplated Au film revealed as-deposited nanoscale voids. Elimination of these voids through process improvement as well as suggested mechanisms for the early failures is discussed.

Analysis and resolution of a thermally accelerated early life failure mechanism in a 40 V GaN FET

An early life failure mechanism was discovered on a 0.25-µm 40V GaN FET technology. Through accelerated life testing (ALT), it was determined that the early life failure mechanism was thermally accelerated with a high activation energy, which means that it is not a concern a normal operating conditions up to the maximum rated junction temperature. Subsequent improvements to the process resulted in elimination of the early life failure mechanism. With the improved process, single-mode ALT lifetime distributions and excellent reliability performance down to low failure fractions were demonstrated.

Perfect Edge 3D™: Enabling Root-Cause Failure Analysis

This paper presents a novel technique used to prepare samples in cross-section using ion beam technology, MCS Perfect Edge™ and Perfect Edge 3D™. The resulting surfaces are deformation-free allowing high magnification and high resolution analysis of subtle nanometer scale features and material changes across a representative sample size (mm's rather than microns). This unique process can be used to prepare most material types and combinations of materials including metals, ceramics, plastics, organics, as well as samples combining hard and soft, thick and thin material layers with zero deformation. True sample structure and key forensic evidence is revealed allowing accurate analysis of early stage failure mechanisms and therefore diagnosis of root-cause. MCS Ltd have also developed a novel process which enables the same deformation-free cross-section whilst retaining access to the sample surface allowing high magnification and resolution analysis in three dimensions, MCS Perfect Edge 3D™. This process has transformed failure analysis capabilities by enabling direct correlation of surface appearance and crosssection condition.

Abstract 322: Balanced, pH-Buffered Preservation Solutions Improved Physiologic Response in Human Saphenous Vein Graft

Introduction: Human saphenous vein (HSV) autografting into the coronary or peripheral arterial system is a widely practiced surgical approach. The primary mechanism of early graft failure is neointimal hyperplasia. Unfortunately, standard practice entails vein preservation in harmful solutions, notably, normal saline (NS). We hypothesized a balanced, euosmolar, pH-buffered solution would promote enhanced vasoreactivity, cellular viability and ultimately, improved patency. Methods: Unmanipulated samples of HSV tissue were obtained from patients undergoing CABG. Rings were cut and placed into University of Wisconsin (UW) solution, low-potassium UW, Celsior, PlasmaLyte (HP) and NS (all heparinized) for one hour, and hung on a muscle bath with unmanipulated control (UM). KCl-dependent contractility, as well as endothelial dependent (EDR) and independent (EIR) relaxation were assessed. Results: One-way ANOVA demonstrated KCl-induced contractility was reduced in NS-preserved HSV; significantly so relative to UW (n=9, p&lt;0.05, Graph A). UW, low-potassium UW and Celsior produced a phenylephrine (PE)-induced contraction significantly greater than that seen in NS (n=9, p&lt;0.05, Graph B), while UM, UW and HP vein show enhanced EDR relative to NS (n=11, p&lt;0.05, Graph C). No EIDR differences were observed (n=7, Graph D). Conclusions: Using physiologic function to reflect graft viability, NS is toxic to HSV. KCl and PE-induced contractility, and EDR were all impaired. Thus, a buffered, balanced solution such as HP or UW is advocated for graft preservation.

Risks to the Blood Supply of the Talus with Four Methods of Total Ankle Arthroplasty

Despite the use of contemporary total ankle arthroplasty implant designs, clinical outcomes of total ankle arthroplasty continue to lag behind those of other joint replacement procedures. Disruption of the extraosseous talar blood supply at the time of ankle replacement may be a factor contributing to talar component subsidence-a common mechanism of early failure following ankle replacement. We evaluated the risk of injury to specific extraosseous arteries supplying the talus associated with specific total ankle arthroplasty implants. Sixteen fresh-frozen through-knee cadaveric specimens were injected with latex and barium sulfate distal to the popliteal trifurcation to visualize the arteries. Four specimens each were prepared for implantation of four contemporary total ankle arthroplasty systems: Scandinavian Total Ankle Replacement (STAR), INBONE II, Salto Talaris, and Trabecular Metal Total Ankle (TMTA). Postoperative computed tomography scans and 6% sodium hypochlorite chemical debridement were used to examine, measure, and document the proximity of the total ankle arthroplasty instrumentation to the extraosseous talar blood supply. All four implant types subjected the extraosseous talar blood supply to the risk of injury. The INBONE subtalar drill hole directly transected the artery of the tarsal canal in three of four specimens. The lateral approach for the TMTA transected the first perforator of the peroneal artery in two of four specimens. The STAR caused medial injury to the deltoid branches in all four specimens, whereas the other three systems did not directly affect this supply (p < 0.005). The Salto Talaris and STAR implants caused injury to the artery of the tarsal canal in one of four specimens. All four total ankle arthroplasty systems tested posed a risk of injury to the extraosseous talar blood supply, but the risks of injury to specific arteries were higher for specific implants.

Bond strength analysis of the bone cement- stem interface of hip arthroplasties

ObjectiveTo study and establish the preliminary linear and modified models for the interface shear mechanics performance between implant and bone cement and to explore its damage significance. MethodThe loosening research between artificial hip joint prosthesis stem and bone cement interface performance can be evaluated by the push-in test. Based on the debonding performance test, the analytical expressions of the average load and displacement from the debonding failure and splitting failure process were deduced and determined. The correlations of the expressions of the average load-displacement and statistical experimental data were analyzed. ResultsIt demonstrated that the interface debonding failure mechanical model could be characterized as interface bond strength mechanical performance. Based on analysis of models and experimental data by the three statistical analysis methods, the results indicated the modified model could be better represented by the interfacial debonding strength properties. The bond stress τ and relative sliding s distribution along the embedment regional were coupling affected by both pressure arch effect and shear lag effect in bone cement. Two stress peaks of implant have been found at the distance from 0.175La loading tip to 0.325La free tip, which also verified the early loosening clinical reports for the proximal and latter region. As the bone cement arch effect, the bond stress peak tend to move to the free tip when the debonding failure would be changed into the splitting failure, which presents a preliminary study on the mechanism of early debonding failure for the stem-cement interface. ConclusionsFunctional models of the stem-bone cement interfacial debonding failure are developed to analyze the relevant mechanism. The different locational titanium alloy stress, and the interfacial bond stress and the relative slides are evaluated to acquire a guide of the different positions of interfacial damage. The coupling effect which is original from the pressure arch and the interfacial shear hysteresis cumulative effect has influence on the interfacial debonding and damage process.