Failure Moment Research Articles

Treatment of Medial Collateral Ligament Injury During Total Knee Arthroplasty With Internal Suture Brace Augmentation: A Cadaveric and Biomechanical Study

Intraoperative medial collateral ligament (MCL) injury during total knee arthroplasty (TKA) is a serious complication. External bracing and/or conversion to a constrained implant has previously been studied. The technique of using an internal high-strength suture brace to augment an MCL repair has been evaluated in the nonarthroplasty patient and could provide an alternate solution. The goal of this study was to determine whether MCL repair with internal suture bracing restores stability of the implanted knee joint. A robotic simulator completed laxity testing on 5 cadaveric knee specimens in 4 sequential phases: (1) intact knee, (2) after implantation with TKA, (3) after sectioning of the MCL, and (4) after MCL repair with suture brace augmentation. Laxity was compared between the different test phases throughout range of motion. Subsequently, the internal brace was tested to failure under valgus load. The MCL repair with internal bracing was effective at restoring laxity in varus-valgus, internal-external, and me-dial-lateral degrees of freedom through midflexion, with limited support at deeper flexion angles and in anterior-posterior laxity. Rotational laxity was not significantly different than intact knee laxity. Generally, medial-lateral translations were less and anterior-posterior translations were greater and were significantly different at 30° to 45° and 90°, respectively. The mean failure moment was 46.4±9.1 Nm, with the primary mode of failure being MCL repair. Primary MCL repair with internal bracing using a high-strength suture augment showed the potential to provide adequate stability and strength to correct MCL incompetence in TKA without the use of an external knee brace or constrained implants. [Orthopedics. 202x;4x(x):xx-xx.].

Modeling of flip-chip underfill delamination and cracking with five input manufacturing variables

The chip corner geometry and the mismatch of the coefficient of thermal expansion cause a local stress concentration in the underfill near the chip corner area. Delamination at the chip-underfill interface and cracks in the underfill often originate from the chip corner and might develop throughout the assembly. This paper presents a modeling approach that allows the estimation of the initial moment of delamination, the growth of delamination and the cracking profiles in flip-chip packages. The reliability model in this work includes five input variables: kerf width, dicing type, laser outrigger presence, sealband material and sealband shape. Thirteen test cells of flip-chip experimental samples were first prepared according to these input variables and were subjected to deep thermal cycling (DTC). C-mode scanning acoustic microscopy (C-SAM), infrared microscopy (IR) and cross-sectioning were used to estimate the underfill failure moments, delamination areas and crack profiles as a reference for subsequent numerical modeling. An artificial neural network (ANN) model was trained to estimate the number of cycles to delamination for cells in the test dataset. The predicted numbers of cycles for all 6 cells in the test dataset were consistent with experimental observations. A finite element model was built to describe the growth of delamination. When the model reached the same delamination area as measured by C-SAM, the difference between the predicted number of cycles and the C-SAM inspection moment were smaller than the inspection interval (250 cycles) for 5 out of 6 cells in validation; the delamination growth model was thus consistent with the experimental observations. The extended finite element method (XFEM) was used to model the underfill cracks without predefined paths. One of the cracks propagated along the diagonal direction, and the other two cracks were along the edges of the die. The directions of edge cracks were in good agreement with the experimental observations, with an error of less than 2.5° for the edge cracks. Overall, with five input manufacturing variables, this modeling approach is able to provide reasonable predictions of the number of cycles to chip-underfill delamination initiation, area of delamination and underfill crack paths in flip-chip packages.

Estimation and prediction for Topp–Leone distribution using double Type-I hybrid censored data

Assuming that the life of the tested samples follows the Topp–Leone distribution, the maximum likelihood estimates and Bayesian estimates of the unknown parameter, reliability and hazard rate are obtained based on the double Type-I hybrid censored samples. According to the observed data, the conditional probability density functions of the future failure moments are obtained, and then the point predictions and interval predictions of the future failure moments are carried out. Based on the double Type-I hybrid censored data, the predictive value and predictive interval of its failure time are given for any tested sample independent and identically distributed in the Topp–Leone distribution. Finally, a numerical example is analysed and the relevant results are calculated.

Fracturing of shales with slots under uniaxial compression parallel to bedding layers

Shale samples containing single pre-machined slots were tested under uniaxial compression directed along with bedding layers. Observed fractures were initiated by the slots, however, their further development was controlled by the shale bedding layers. Slots normal to the loading direction also cause fracturing and reduce failure load. The fracturing is initiated by tensile stress generated at the slot surface due to convergence of the initial open slot. Therefore, the presence of initial aperture in pre-existing cracks or fractures is capable of changing the mechanism of fracture generation. Three kinds of macroscopic fractures are observed: tensile fractures along bedding layers, shear fractures along the inclined direction, and buckling fractures at the final failure moment. Three types of microcracks are identified: shear microcracks produced from initial weak micro-planes unrelated to the bedding layers, tensile microcracks produced from the shear microcracks in the form of wing cracks, and shear microcracks induced by high uniaxial compression stress. The growth of wing cracks can be assisted by the bedding layers. The research results will contribute to the understanding of failure mechanisms of rocks containing prominent bedding layers.

Probabilistic Temporal Modeling for Unintentional Action Localization.

Humans have the inherent advantage of understanding action intention, while it is an enormous challenge to train the machine to localize unintentional action in videos due to the lack of reliable annotations for stable training. The annotations of unintentional action are unreliable since different annotators are affected by their subjective appraisals and intrinsic ambiguity, which brings heavy difficulties for the training. To address this issue, we propose a probabilistic framework for unintentional action localization by modeling the uncertainty of annotations. Our framework consists of two main components, including Temporal Label Aggregation (TLA) and Dense Probabilistic Localization (DPL). We first formulate each annotated failure moment as a temporal label distribution. Then we propose a TLA component to aggregate temporal label distributions of different failure moments in an online manner and generate dense probabilistic supervision. Based on TLA, We further develop a DPL component to jointly train three heads (i.e., probabilistic dense classification, probabilistic temporal detection, and probabilistic regression) with different supervision granularities and make them highly collaborative. We evaluate our approach on the largest unintentional action dataset OOPS and demonstrate that our approach can achieve significant improvement over the baseline and state-of-the-art methods.

Experimental investigation of damage evolution and failure criterion on hollow cylindrical rock samples with different bore diameters

The roadway direction is often parallel to the direction of the maximum principal stress for the structure arrangement of underground roadway. To study the instability mechanism of roadway under the maximum principal stress, a series of uniaxial compression acoustic emission (AE) experiments were carried out on hollow red sandstone and granite rock samples with different bore diameters. The test results suggest that the oblique shear or X-shaped shear failure occurs in hollow rock samples, and the failure process is accompanied by a sudden jump in accumulative energy of AE signals, at the same time, the ringing count arrived at peak value. The increase in bore diameter haves contributed to the decline of ringing count and accumulative energy. A statistical damage constitutive model of Weibull distribution was established for hollow rock samples. On the basis of optimizing the damage variable, a damage constitutive model based on AE ringing count was obtained, which can better describe the damage state and stress state of rock samples. The AE accumulative energy was selected as the state variable, and the failure criterion model was finished based on the cusp catastrophe theory to estimate the rock sample failure. The judgment results show that the failure moment of rock sample is accurately included in the judgment time interval. This research can provide reference and technical support for the stability control and monitoring of underground engineering roadways.

Testing and numerical modelling of circular CFDST cross-sections with stainless steel outer tubes in bending

The structural performance of circular concrete-filled double skin tubular (CFDST) cross-sections with stainless steel outer tubes has been examined herein based on experiments and numerical modelling. A laboratory testing programme comprising a total of 22 four-point bending tests was performed on seven CFDST cross-sections with varying concrete grades. The details of the test rig and procedures, as well as the key test observations, including the failure moment capacities, moment–curvature curves and failure modes, are fully reported. A numerical modelling programme was then carried out; a finite element (FE) model was first established to replicate the test observations, and then adopted to conduct a parametric study to acquire further FE data over a broader spectrum of material strengths and cross-section slendernesses. Based on the combined set of test and FE results, the general design provisions for concrete-filled carbon steel members in the current European and American design codes were evaluated for their applicability to the studied CFDST cross-sections. Overall, the results revealed that both of the examined design codes yield unduly conservative (less so for the higher concrete grades) and scattered moment resistance predictions, though some moment resistances predicted from the European code were on the unsafe side. Modifications, including a concrete reduction factor η to reflect the reduced relative effectiveness of using higher concrete grades and a modified stress distribution considering the partial spread of plasticity, were proposed and shown to improve the consistency of the resistance predictions. Finally, the reliability of the current and modified design rules was demonstrated through statistical analyses.

Study on the characteristics of the materials and manufacturing quality to shrapnel-type couplings properties

With the development and application for the ultra-precision machinery industries and smart machinery have become prosperous. The precision transmission sub-system is an important part of the precision machinery equipment and smart machinery industries. Then shrapnel-type coupling is an important part of the precision transmission system. In the shrapnel-type couplings with high precision, high reliability, and high efficiency. The design of shrapnel-type couplings needs to correct and improved in the manufacturing with very high-precision inspection equipment, and expert measurement technology. The high quality of shrapnel-type couplings, materials and manufacturing qualities are the main factor for high precision, high reliability, and high efficiency. This paper will be a depth study of the body materials and manufacturing qualities of shrapnel-type couplings. The inner hole contact surfaces of the shrapnel-type couplings to connect between each other connecter tested the properties of the coupling via toque-torque angle testing equipment with changing the shrapnel-type couplings body materials and manufacturing different roughness of inner hole. The key characteristics that affect the torsional rigidity and failure torque of the coupling grasped are found out using the self-developed toque-twist angle testing machine. The body of the shrapnel-type couplings made with 7075 aluminium alloy and 6061 aluminium alloy. Through experiments, we can understand the influence of different materials bodies on the torsional rigidity and failure moment of the shrapnel-type couplings. From experimental results, that 7075 aluminium alloy is better than 6061 aluminium alloy of torsional rigidity or failure moment. As the inner hole surface roughness of the shrapnel-type couplings smaller has a higher failure torque of coupling.

Sustainable Implementation of Recycled Tire-Derived Aggregate as a Lightweight Backfill for Retaining Walls

The study examined the use of recycled tire-derived aggregate (TDA) mixed with kaolin for retaining wall applications. The effects of the TDA content on the geotechnical properties of TDA-kaolin specimens such as the internal friction angle, maximum dry density (MDD), optimum moisture content (OMC) and saturated density (SD) were investigated. A total of 13 physical model tests were performed on a polymer concrete retaining wall using kaolin and TDA-kaolin mixtures as backfill material. Powdery, shredded, small-sized granular (1–4 mm) and large-sized granular (5–8 mm) TDA were mixed with kaolin at contents of 0%, 20%, 40%, and 60% by weight. The lateral wall displacement was measured on a fabricated steel strip footing close to the wall during loading. Lateral wall displacement also was simulated using finite element (FE) software (Optum G2). The results indicated that the addition of 60% TDA decreased the internal friction angle of the samples up to 8% compared to pure kaolin. In addition, the TDA particles caused the MDD of the TDA-kaolin samples to decrease up to 45%. The physical modeling results indicated that the kaolin samples mixed with 60% shredded TDA showed the highest elasticity in all tests at the failure moment of the footing.

An application of the direct strength method to the design of castellated beams subject to flexure

The aim of this research is to investigate the instability of castellated beams and the interaction between lateral-torsional and compression tee local buckling modes. Firstly, a comprehensive study of 197 simply supported Litzka castellated beams under pure bending is carried out. The study involves eigenvalue and fully nonlinear finite element analyses, e.g. including both material nonlinearity and geometric imperfections. After computing the critical moments associated to local and global modes and the ultimate moments, an approach based on the Direct Strength Method is proposed using regression techniques to derive strength prediction equations. The developed method is then compared with current standards procedures. The results show that the proposed equation predicts better strength values in all cases, especially those in which local and/or interaction failure modes dominate the behavior of the beam. The results also show that some of the procedures suggested in standards and guides for the design of castellated beams under flexure, either underestimate or overestimate the failure moment when considering the interaction between global buckling mode and plastification.

Wide–Narrow Row Planting Pattern Increases Root Lodging Resistance by Adjusting Root Architecture and Root Physiological Activity in Maize (Zea mays L.) in Northeast China

Root lodging (RL) in maize can reduce yield and grain quality. A wide–narrow row planting pattern can increase maize yield in the growing regions of northeastern China, but whether it can improve RL resistance is not clear. Therefore, in this study, the root architecture distribution, root physiological activity, and root lodging rate under planting pattern 1 (uniform ridge of 65 cm, east–west ridge direction) and pattern 2 (wide–narrow rows, 40 double narrow rows and 90 wide rows, north–south ridge direction) were studied. The results showed that the RL rate under pattern 2 was significantly lower than that under pattern 1. The number and diameter of nodal roots on the upper node, the root failure moment, and the root bleeding sap intensity at the 3 weeks after VT under pattern 2 were significantly higher than those under pattern 1. Root length density in the 0–40 cm soil layer tended to be inter-row distributed. Therefore, the RL resistance of maize under pattern 2 was increased through an adjustment in the root architecture distribution and root physiological activity in northeastern China.

Effects of connections on the behaviour of cold-formed unlipped channel section bearers

Cold-formed steel (CFS) unlipped channel sections are commonly used as bearers in floor systems while rectangular hollow sections (RHS) are used as joists. The transverse loads from the joists do not pass through the shear centre of channel bearers due to different joist to bearer and bearer to column connections. Hence, the channel bearers are subjected to torsion in addition to concentrated loads and bending. This study investigated the effects of two joist to bearer (bolted/welded) connections, two bearer to column (cap plate/angle cleat) connections and fly braces on the structural behaviour of channel bearers. Eight full-scale tests were performed using simplified floor arrangements, made of two unlipped channel bearers with eight and six RHS joists located at 450 mm spacing. Suitable finite element models of tested channel bearers including their connections were developed and validated in terms of ultimate failure moment, failure mode and deflections. A parametric study was then performed using the validated finite element models. The effects of bolted/welded joist to bearer connections and cap plate/angle cleat bearer to column connections on the behaviour of channel bearers were determined and discussed based on the experimental and numerical results. Suitable recommendations were then made to the design methods based on the observed failure modes, and the most suitable combination of connections for the CFS floor systems investigated in this study.

Experimental study of moment carrying behavior of typical Tibetan timber beam-column joints

This study aimed to investigate the moment carrying behavior of typical Tibetan timber beam-column joints under monotonic vertical static load and also evaluate the influence of length ratio of Gongmu to beam (LRGB) and dowels layout on the structural performance of the joint. Six full-scale specimens were fabricated with same construction but different Gongmu length and dowels position. The moment carrying performance of beam-column joints in terms of failure mode, moment resistance, and rotational stiffness of joints were obtained via monotonic loading tests. Test results indicated that all joints are characterized by compressive failure perpendicular to grain of Ludou. Additionally, it was found that greater LRGB leads to greater initial rotational stiffness and maximum moment of the joint by an increase of restraint length for beam end; however, offsetting dowels toward column resulted smaller stiffness and ultimate bending moment of joints, particularly, offsetting Beam-Gongmu dowels toward column changed the moment-rotation curve pattern of the beam-column joint, accompanied by a hardening stiffness at last phase. Furthermore, a simplified trilinear model was proposed to represent the moment-rotation relationship of the typical Tibetan timber beam-column joint.

Investigation on Acoustic Emission Kaiser Effect and Frequency Spectrum Characteristics of Rock Joints Subjected to Multilevel Cyclic Shear Loads

Rock joints have obvious acoustic emission (AE) Kaiser effect and Felicity effect under multilevel cyclic shear conditions. The TFD-20H/50J rock shear apparatus was used to carry out cyclic loading and unloading joint shear tests, and the acoustic emission parameters and frequency spectrum characteristics of the whole shearing process were analyzed. The results show that, under the cyclic loading, the shear stress-displacement curve forms several cyclic hysteresis loops, and the number of loops increases with the increase of normal stress. With the cycles increase, the shear damage gradually increases, and the Felicity ratio gradually decreases. The Felicity ratio at the final shear failure moment is about 0.94~0.99. The ratio of the RA value (rise time/amplitude) and the average frequency value (RA-AF) is used to classify the cracking mode of the joint sample. There are two AE crack signal types (tensile type and shear type) during shear damage. The peak frequency is displayed as high, medium, and low three frequency bands, which are distributed in the range of 0~35 kHz, 35~122 kHz, and 122~300 kHz, respectively. Both low-frequency and high-frequency signals account for less than 10%, and medium-frequency signals account for more than 90%. The research of the AE monitoring signals of multilevel shear behaviors can help understand the shear-friction mechanisms of rock joints.

Load-Sharing Reliability Models with Different Component Sensitivities to Other Components’ Working States

AbstractWe study the distributions of component and system lifetimes under the time-homogeneous load-sharing model, where the multivariate conditional hazard rates of working components depend only on the set of failed components, and not on their failure moments or the time elapsed from the start of system operation. Then we analyze its time-heterogeneous extension, in which the distributions of consecutive failure times, single component lifetimes, and system lifetimes coincide with mixtures of distributions of generalized order statistics. Finally we focus on some specific forms of the time-nonhomogeneous load-sharing model.

Experimental investigation on cold-formed steel lipped channel beams affected by local-distortional interaction under non-uniform bending

This paper reports an experimental investigation, carried out at The University of Hong Kong, on the behaviour of cold-formed steel lipped channel beams affected by local-distortional (L-D) interaction under non-uniform bending – to the authors’ best knowledge, these are the first tests specifically devoted to this topic. This investigation consists of 16 non-conventional four-point simply supported bending tests involving twin lipped channel beams arranged in a “back-to-back” configuration and laterally restrained at the loading points. The 32 lipped channel specimens were brake-pressed from high-strength zinc-coated G450 grade structural steel sheets. Tensile coupon tests were performed to obtain the specimen material properties and initial geometrical imperfections were measured prior to testing. The beam geometries were carefully selected to enable testing beams that are prone to “true L-D interaction” (close critical distortional-to-local buckling moments) when acted by trapezoidal bending moment diagrams with four distinct gradients – all the tested specimens exhibited the sought L-D interactive nature. The output of the experimental investigation consists of (i) applied moment vs. displacement equilibrium paths, (ii) photos showing beam deformed configurations along those paths (including the failure modes) and (iii) the failure moment data. Lastly, the experimental failure moments obtained are compared with their predictions provided by the (i) current local and distortional Direct Strength Method (DSM) strength curves and (ii) available DSM-based approaches against L-D interactive failures, which were developed and calibrated exclusively in the context of beams subjected to uniform bending.

Bearing Life Prediction Based on SPSS and Grey Prediction Model

Many sophisticated weapons and equipment have bearings, which can play a vital role of reducing friction to improve the efficiency of equipment. The performance of CV can quantify the processing of the bearing, it will make the staff have a reference standard to evaluate the working condition of the bearing. Primarily, according to the known data, this paper calculated the real CV value with the maximum likelihood estimation method. Both SPSS curve estimation and the method of cumulative grey prediction model were used to train the part of the real data. Then, the failure moment of bearings failure moment can be simulated. The final step was to calculate the relative error of predicted CV value. Compared with the predicted results of the original grey prediction model (GM (1,1)), the three relative errors were 6.9502 percent, 4.6433 percent and 10.5938 percent. Three methods above all have certain practical value in engineering. However, the effect of cumulative grey prediction is better obviously.

Improvement of maintenance and repair system of internal combustion engines of automotive equipment

The paper analyzes the operating conditions of road transport affecting its reliability. It is concluded that it is necessary to develop scientifically based strategies flexible of AE maintenance based on predicting the failure moment by extrapolating the process of time drift of the informative parameters of the AE at the interval of its intended use. To solve this problem, we propose an approach based on the use of quasi-deterministic models of the time drift of the AE parameters, which allow to obtain analytical expressions for the main reliability indicators -density of the distribution time to failure and the probability of failure -free operation at a given time interval. On the basis of these indicators of reliability in operation, performance indicators have been formed allowing determining of the optimal maintenance frequency. In the final part of the article, the author proposes an algorithm and a methodology that allows organizing flexible strategies for AE maintenance, considering special conditions of its operation.

Evaluation of a Feline Bone Surrogate and In Vitro Mechanical Comparison of Small Interlocking Nail Systems in Mediolateral Bending.

The aim of this study was to (1) evaluate bending structural properties of a machined short fibre epoxy (SFE) feline bone surrogate (FBS), (2) compare the bending behaviour of small angle-stable interlocking nails (I-Loc; Targon) and locking compression plates (LCP) and (3) evaluate the effect of implant removal on FBS bending strength. Part 1: Feline cadaveric femurs (n = 10) and FBS (n = 4) underwent cyclic four-point bending and load to failure. Part 2: Fracture gap FBS constructs (n = 4/group) were stabilized in a bridging fashion with either I-Loc 3 and 4, Targon 2.5 and 3.0, LCP 2.0 and 2.4, then cyclically bent. Part 3: Intact FBS with pilot holes, simulating explantation, (n = 4/group) underwent destructive bending tests. Bending compliance, angular deformation and failure moment (FM) were statistically compared (p < 0.05). Native bone and FBS were similar for all outcome measures (p > 0.05). The smallest and largest bending compliance and angular deformation were seen in the I-Loc 4 and LCP 2.0 respectively (p < 0.05). While explanted Targon FBS had the lowest FM (p < 0.05), I-Loc and LCP constructs FM were not different (p > 0.05). The similar bending properties of short fibre epoxy made FBS and native feline femurs suggest that this model could be used for mechanical testing of implants designed for feline long bone osteosynthesis. The I-Loc constructs smaller angular deformation which also suggests that these implants represent a valid alternative to size-matched Targon and LCP for feline fracture osteosynthesis. The significantly lower FM of explanted Targon may increase the risk of secondary fracture following implant removal.

New predictive equations for lateral-distortional buckling capacity assessment of cellular steel beams

Assessment of the ultimate capacity of the cellular steel beams subjected to the lateral-torsional buckling containing web distortion (lateral-distortional buckling) was rarely investigated. So far, there is no accurate formula to predict the lateral-distortional buckling (LDB) capacity of such members. Here, extensive simulations (660 specimens) based on the nonlinear finite element analysis (FEA) were carried out to simulate the cellular steel beams in distortional-buckling mode. The influence of eight parameters that may affect the LDB capacity was deeply investigated. Then, gene expression programming (GEP) and nonlinear multiple regression (NMR) algorithms progressed as predictive models to obtain formulae for measuring the failure moment capacity of the cellular steel beams. The used data for the GEP and NMR models development, obtained from the FEM simulations that were done initially. It was attempted to derive exact enough formulae, which considers all the variables that may affect the LDB capacity of cellular steel beams. The validation of the GEP and NMR models have been further verified by several statistical criteria. Finally, a comparison was performed between the proposed formulae and the predictions obtained from AS4100, EC3, and AISC codes. It was shown that the proposed formulae are enough exact and applicable to use by practicing engineers.