Deflection Data Research Articles

Application of resampling techniques to improve the quality of survival analysis risk curves for human frontal bone fracture

BackgroundIn automotive events, head injuries (skull fractures and/or brain injuries) are associated with head contact loading. While the widely-used head injury criterion is based on frontal bone fracture and linear accelerations, injury risk curves were not developed from original datasets. ObjectivesDevelop skull fracture-based risk curves for using previously published data and apply resampling techniques to assess their qualities. MethodsForce, deflection, energy, and stiffness data from thirteen human cadaver head impact tests were used to develop risk curves using parametric survival analysis. Injuries occurred to all specimens. Data points were treated as uncensored. Variables were ranked, and the variable best explaining the underlying fracture response was determined using the Brier Score Metric (BSM). The qualities of the risk curves were determined using normalized confidence interval sizes. Statistical resampling methods were used to assess the quality of the risk curves and the impact of the sample size by conducting 2000 simulations. Sample sizes ranged from 13 to 26. FindingsThe Weibull distribution was optimal for all the response variables, except deflection (log-logistic). The quality of the risk curves was the highest for deflection. This variable best explained the underlying head injury response, based on BSM. Improvements in the quality of the risk curves were achieved with additional samples of force and deflection (<13), while energy and stiffness variables required more size. Individual risk curves are given. InterpretationThese probability curves from head contact loading add to the understanding skull fractures and can be used to improve safety in injury producing environments.

A performance-based evaluation of chemically similar (carbonate) tempers from Late Prehistoric (AD 1200-1700) Ohio: Implications for human selection and production of ceramic technology.

PurposeThis study was designed to assess the mechanical properties of two calcium carbonate tempers, limestone and burnt shell. These tempers have been previously compared, in separate studies, to silicate-based grit or sand temper and, relative to the latter, are assumed to possess similar mechanical properties. However, their simultaneous use at the Morrison Village site begs the question: do these two calcium carbonate tempers indeed possess similar mechanical properties? In order to assess their performance characteristics, a side-by-side controlled experimental test was conducted to determine the degree of similarity in providing increased vessel strength and toughness.MethodsStandardized ceramic test samples were systematically prepared via a set, explicit protocol. An Instron Series IX universal testing machine configured with a four-point flexural test jig was used to perform a flexural strength test of the test samples. The Instron load and deflection data were used to calculate three values related to mechanical performance: peak load, modulus of rupture, and modulus of elasticity.ResultsAll four comparative tests clearly show substantial differences in peak load, modulus of rupture, and modulus of elasticity. These differences are statistically significant for each performance attribute in every iteration of the experiment and as indicated by Mann-Whitney U Tests.ConclusionsThese results do not support the hypothesis that limestone and burnt shell offer the same performance characteristics. These results have implications for our understanding of prehistoric human selection of temper and the evolution of ceramic technology. Although both carbonate-based tempers are currently thought to offer the same benefits during the initial phase of pottery production, their contrasting post firing properties would have provided distinct benefits in different contexts. Future assessments of the Morrison Village ceramic assemblage should focus on residue analysis, or other functional indicators, to support or falsify this hypothesis.

CFRP strips for enhancing flexural performance of RC beams by SNSM strengthening technique

Side Near Surface Mounted (SNSM) strengthening technique is among the latest technique introduced recently. In this paper, SNSM carbon fiber reinforced polymer (CFRP) strips strengthening technique is proposed for enhancing the flexural performance of reinforced concrete (RC) beams. A total of seven RC beam specimens were tested: one un-strengthened control specimen, and six specimens strengthened by SNSM-CFRP strips. All beam specimens were tested under four-point bending. Analytical prediction methods were used to verify the experimental results. The load, mid-span, deflection, and strains data were recorded until failure of the specimens. The ductility, stiffness, and energy absorption capacity of the strengthened specimens by CFRP strips were enhanced due to SNSM technique. The results also showed that the SNSM-CFRP strips strengthening technique significantly enhanced the first cracking, yield, and ultimate load capacities up to 153%, 108%, and 147% respectively, compared with that of the control beam. Further, the comparison between the experimental and predicted values shows good agreement.

Deflection detection and curve fitting in three-roll continuous straightening process for LSAW pipes

Aiming at the low efficiency of three-point mold bending straightening, a new method of three-roll continuous straightening is proposed in this paper, which is full in consideration of the geometric features and bending characteristics of LSAW pipes. Using the characteristics of the roll straightening device, a straightness detection method for large pipes is proposed just by adding a laser displacement sensor, and the calculation model for overall deflection based on local deflection is established. Based on the detected deflection data, a piecewise fitting algorithm with constraints by introducing the Kuhn-Tucker condition is proposed for straightness calculation, and a simple polynomial fitting method with fourth order is determined for the calculation of curvature and straightening moment. Further, using the semi-automatic experimental prototype for small pipes, the deflection detection experiments show that the overall deflection error is less than 3.5% compared with that of CMM, the piecewise fitting results show that the ideal order of the mid-segment is 10-th, and the three-roll continuous straightening experiments show that the novel method can correct the straightness to less than 0.2%, meeting the standard requirements.

Crushed concrete in road structures – two decades of experience

Since the early 1990s, crushed concrete aggregate (CCA)/recycled concrete aggregate has been successfully used in Finnish road constructions. The aim of this paper is to analyse the long-term behaviour of CCA and to compare CCA with conventional mineral aggregates in road structures. The analysed trial sections consist of the road and highway pavements where CCA has been used in the base and subbase layers. The first studied Finnish trial section was constructed in 1995, which has enabled nearly two decades of follow-up studies. In total, five follow-up trial sections were studied. E-modulus of pavement layers was determined using the deflection data from falling weight deflectometer measurements. The studies revealed excellent long-term behaviour in the CCA build pavements and validated the suitability of chosen design parameters in previous guidelines. In this study, the sections consisting of maximum 50 mm particles of CCA in the base or subbase layer gained 10–25% larger bearing capacity in 13–15 years after construction than the reference pavements that were constructed with crushed rock. The increase of the CCA stiffness was faster in the first years after construction and in the 2–5 years little or insignificant increase in such stiffness could be observed.

A Study of the Structural Performance of Flexible Pavements Using Traffic Speed Deflectometer

Abstract The falling weight deflectometer (FWD) is a non-destructive testing device that has been used by many road agencies worldwide since 1980 for structural evaluation of flexible pavements. In early 2000, the world first Doppler laser-based traffic speed deflectometer (TSD) was developed by Greenwood Engineering, and now eight TSD vehicles are in use worldwide. The two main advantages of the TSD technology are: (a) the ability to carry out continuous bearing capacity measurements instead of discrete points, (b) that testing can be carried out at traffic speeds without the need for lane closures with a stationary device such as FWD. The objective of this paper was to study the structural performance of flexible pavements using TSD deflection data. The study successfully established a correlation between maximum deflections TSD-D0 and FWD-D0 that are derived from the two devices. This study also drew some interesting conclusions in that deflection data collected by TSD could be transformed to FWD equivalent structural numbers with simple models as derived in the study. The outcome of this study was an established methodology for reporting structural performance at network level utilizing TSD deflection data.

Bending of thin rectangular plates with variable-thickness in a hygrothermal environment

This paper presents hygrothermomechanical bending analysis of variable-thickness thin rectangular plates. Two opposite edges of the present variable-thickness plate are clamped while the other opposite edges are simply-supported. The present plate has varying thickness between its two edges and found in a hygrothermal environment. The exact analytical solutions are developed for the bending behavior of thin rectangular plates subjected to transverse uniformly distributed load. Numerical results are presented by using both Lévy-type approach and the small parameter method. A validation example is employed with existing literature results. More reported and illustrated data for deflections, bending moments and bending stresses are investigated.

Simultaneous Flowfield and Surface-Deflection Measurements of an Axisymmetric Jet and Adjacent Surface

The interaction of an underexpanded jet and a nearby adjacent compliant surface is considered in an effort to gain insight into the relevant fluid–structure interaction. High-quality simultaneous flowfield and surface-deflection data were obtained in this high-Reynolds-number flow using nonintrusive, full-field, optical diagnostics (planar particle image velocimetry and stereo/three-dimensional digital image correlation, respectively). Both experimental setups were rigorously validated in terms of their measurement resolution and accuracy, both individually and in a combined manner. The full-field surface deflection data indicate that the surface has a predominantly quasi-static response characterized by a “standing-wave” type contour along the jet axis. A large jetward deflection, on the order of 10 plate thicknesses, was observed near the first shock-cell region, which is consistent with previously obtained rigid-surface case surface pressure measurements. The compliant-surface flowfield was analyzed and compared to the rigid-surface case results in key regions: the initial expansion region, through the shock/boundary-layer interaction, the shock/boundary-layer interaction separation region, the shock-cell structure of the remainder of the jet plume, the near-wall boundary layer, and the far-field conditions. Notable differences were observed before, within, and after the shock/boundary-layer interaction region as well as within the boundary layer and in the shock-cell structure.

New numerical tools to calibrate the Two Curves Method using the CTOA criterion

Based on the Crack-Tip Opening Angle (CTOA) fracture criterion and the finite element method coupled with the node release technique, a New Two-Curve method (TCM) was proposed for the prediction of gas pipelines' crack arrestability. Arrest pressure, crack propagation velocity and length were predicted successfully.A modern high-toughness pipeline made in API 5L X65 pipeline steel with 19 mm wall thickness and a 355 mm external diameter was investigated. The critical CTOA (CTOAC) property was measured with a Modified Compact Tension (MCT) specimen at room temperature. A new method for evaluating the CTOAC by combining experimental load–deflection data and finite element analysis was implemented. The results of the CTOAC were compared with the available CTOAC data.The results for the New Two-Curve method were discussed and compared with those obtained by well-established methods such as Battelle-TCM, HLP and HLP-Sumitomo.

A structural assessment of unrefined sintered lunar regolith simulant

The potential of utilizing lunar regolith as the raw material for manufacturing structural members is very appealing for future exploration and settlement of the Moon. Future lunar missions will depend on in-situ resource utilization (ISRU) for structural components, among other things. Sintered lunar regolith has been proposed as a structural material. In general, it has been assumed that the regolith would be at least minimally processed before use. We propose the possibility of manufacturing structural components directly using unrefined sintered lunar regolith with the advantage of requiring fewer specialized material processing equipment.Our purpose in this study was the quantification of the material properties of unrefined sintered lunar regolith simulant. Two batches of sintered lunar regolith simulant JSC-1A samples, with porosities of 1.44% and 11.78%, underwent compression testing using an Instron series 4500 Universal Test System machine. Material properties were evaluated from the acquired load vs. deflection data. Stress vs. strain, modulus of elasticity, toughness, bulk modulus and compressive strength were evaluated as a function of porosity. The average compressive strength of the 1.44% porosity material was 218.8 MPa, and 84.6 MPa for the 11.78% porosity material. Our tests show that even unrefined sintered 11.78% porosity lunar regolith holds the possibility of being a useful structural material for lunar construction. Comparing our experimental results with those of other ISRU derived structural materials, unrefined sintered lunar regolith is expected to be one of the strongest material derived from lunar sources.

Torsional Stiffness Improvement of Truck Chassis Using Finite Elemen Method

This thesis deals with a study on the torsional stiffness of existing truck chassis and some others improved models by using finite element method. The objective of this study is to improve the torsional stiffness by design and to provide simulation of the deflection on the chassis. The problem on the chassis is the deflection on the chassis whereas higher displacement will affect the torsional stiffness of the truck. ABAQUS was used as it is a powerful engineering simulation tool based on the finite element method. The magnitude of torsional stiffness for existing and modified models were calculated based on data of deflection of each models which were obtained from the finite element simulation. The multi holes model was choosen as the best proposed model due to the highest of torsional stffness as comparison result among existing and modified models.

Structural Model for Longitudinal Cracking in Bonded Whitetopping with a 1.83 m×1.83 m Joint Spacing

Longitudinal cracking has been identified as the predominant distress in thin bonded whitetopping with a 1.83-m (6-ft) longitudinal joint spacing. However, the structural models in existing whitetopping design procedures do not address this particular mode of failure. To better predict the design stresses and therefore to provide a more accurate design, this paper develops a new structural model for predicting longitudinal cracking, which accounts for the combined effect of wheel load and temperature gradient, using one specific three-dimensional finite-element model. The model is validated by matching field deflection data from existing whitetopping sections to predicted deflections. A database is populated with this model and is used in the development of a new closed-form structural model to predict the critical stress with respect to longitudinal cracking. A sensitivity study is conducted to evaluate the new structural model.

Development of Deformed Computer-Aided Design Geometries for the Sixth Drag Prediction Workshop

A method for modifying the shape of digital geometry representations used in computer-aided design applications according to experimental pointwise deflection data is described. In the pilot study presented here, the method is applied to the computer-aided design geometry of an aircraft wing that is deformed using measured deflections obtained from the associated wing model during a wind-tunnel test. The method provides various advantages in computational fluid dynamics and other applications. Numerical grids generated on the deformed geometry yield an improved correlation of computational fluid dynamics results to wind-tunnel data without the need for aeroelastic computations, which require coupling to a structural model. Additionally, the method is beneficial in aerodynamic optimization, where the optimized shape is usually given in the form of a computational fluid dynamics surface mesh or nodal deflections that, for further processing or manufacturing purposes, need to be transferred into a computer-aided design geometry description. The paper presents an application to NASA’s Common Research Model transport aircraft configuration, where deformation measurements from a test campaign in the European Transonic Wind Tunnel are processed to provide deformed computer-aided design geometries for the Sixth AIAA Computational Fluid Dynamics Drag Prediction Workshop.

Objective Identification of Trough Lines Using Gridded Wind Field Data

An objective method was developed to analyze longwave and shortwave trough lines in wind field data using different methods, given that these trough lines were researched in different ways. Longwave trough lines were analyzed by locating the cyclonic center and filtering candidate trough points simultaneously; the candidate longwave trough points were then traced based on distance and angle conditions. Next, candidate shortwave trough points were determined based on angular deflection and vorticity data, which were clustered and fitted to a curve for extraction. This method was applied to wind field data from the National Center for Environmental Prediction (NCEP) to analyze trough lines in East Asia and South Asia. The experimental results show that our method can effectively identify trough lines by comparing them with manual analysis results. The statistical results indicate that the method more precisely identifies longwave trough lines than shortwave trough lines, and that trough lines during the fall and winter are more accurately and effectively identified than those during the spring and summer.

Use of Embedded Sensors to Evaluate Performance of Traffic Speed Deflection Devices

Abstract Structural adequacy, which is an important aspect of pavement management activities, is typically evaluated using surface pavement deflections measured by the falling weight deflectometer (FWD). Technology that can collect continuous deflection data at traffic speeds can potentially supplant single-point location deflection measurements provided by the FWD for network-level pavement management system (PMS) applications. Previous studies have evaluated the traffic speed deflection devices (TSDD) performance by comparing their results with the FWD measurements. Although appropriate correlations and indices to compensate for the differences in load have been made, a direct comparison under the same loading conditions has not been reported in the literature. The purpose of this paper was to present the results of a field study to evaluate TSDDs by comparing their pavement deflection parameters with those from embedded sensors under actual loads. Two TSDDs were used in this study: the Greenwood traffic speed deflectometer (TSD), and the Applied Research Associates, Inc. (ARA) rolling wheel deflectometer (RWD). The lessons learned from the study are emphasized for further consideration toward developing a calibration methodology for value-added future analyses.

An analysis of the design of a fire-resistant elevator landing door

This study first conducts fire resistance tests on the elevator door, then acquires the deflection data. The data are used as the basis for the subsequent simulation verification and analysis. Moreover, the finite element analysis software ANSYS is adopted to simulate and further analyzes the fire resistance of the elevator landing door. The variations in the structural strength of the elevator landing door under a high-temperature fire are discussed. An influence analysis of the fire performance of the elevator landing door is then performed by varying different parameters, including the landing door thickness and the reinforcement attributes. The quantitative data are expected to provide a reference for the design of fire-resistant elevator landing doors.

Ultrasound field characterization using synthetic schlieren tomography.

Synthetic schlieren imaging, also known as background oriented schlieren imaging, is used to determine the acoustical field of a focused ultrasound transducer operating at 1.01 MHz frequency with peak pressure amplitude of 0.97 MPa. The measurement setup is composed of a commercial off-the-shelf digital single-lens reflex (DSLR) camera with an ordinary objective, a high power light-emitting diode driven in pulsating mode, water tank, ultrasound transducer, rotation stage, and driving electronics. Measurements are performed in tomographic fashion by rotating the ultrasound transducer within the water tank and photographing an imaged target behind the ultrasound field. The photographs are processed with a Horn-Schunck-type algorithm, commonly used in optical flow analysis, in order to determine the deflection of light rays as caused by ultrasound field induced acousto-optic effect. Inverse Radon transform is then used, with the deflection data, to obtain three-dimensional spatial distribution of the pressure field gradient, from which an approximation of the ultrasonic pressure field is computed. The pressure field obtained with synthetic schlieren tomography is then compared to hydrophone measurements mainly qualitatively.

Modification Research of Pavement Deflection Representative Value Formula Based on Wavelet Transform

Because the measured deflection of expressway asphalt pavement does not obey the normal distribution, the calculation formula of deflection representative value can’t be used. In order to solve it, in the premise of keeping original characteristics of the measured deflection data, by using the two times standard deviation method, the specific data of the original measured deflection data were eliminated and then furthermore the noise of the deflection data was managed through wavelet transform. The normal distribution ratio of the measured deflection data of asphalt pavement were increased from 20.0% to 86.7%, the requirement of the original formula of deflection representative value was meet, so according to the method, the original formula of the deflection representative value can be modified. Engineering Practice shows that the revised deflection representative value calculation formula that was applied to evaluate the pavement structural strength was suitable. Its evaluation result can reflect the actual technical condition of roads.

Study on the Test System of Yunluo Long-life Asphalt Experimental Road

In order to grasp the mechanical response of the asphalt concrete pavement structure, on the basis of the layer theory of the asphalt pavement structure and the measurement system, the measured data post-processing application of the asphalt pavement structure was developed. Based on the Yunluo expressway experimental section of Guangdong Province, according to the calculation theory of road structure, the finite element analysis model of the pavement structure was established, and the mechanical properties of the asphalt pavement structure of the experimental section were analysed. It was determined that the layout scheme of the asphalt pavement corresponding structure layer temperature and strain sensor and the road test plan based on FWD. By using FWD as the loading tool, the resistance strain sensor were used to dynamically monitor the transverse and longitudinal strains of the road structural layers in order to grasp the dynamic response of the asphalt pavement. By using the FWD's own deflection detection system, the measured deflection data of the pavement structure were obtained. At the same time, taking into account the processing difficulties of mass measurement data, the postprocessing application of the measured data was developed. The results show that according to the theoretical analysis, the measured system was reasonable, the layout scheme and the test plan were proper. The measured data postprocessing applications can offer a better analysis platform for analysts.

A measuring system for determination of a cantilever beam support moment

This investigation is aimed to develop a model of experimental-computation determination of a support moment of a cantilever beam loaded with concentrated force at its end including the optimal choice of coordinates of deflection data points and parameters of transformation of deflection data in case of insufficient accuracy of the assignment of initial parameters (support settlement, angle of rotation of the bearing section) and cantilever beam length. The influence of distribution and characteristics of sensors on the cantilever beam on the accuracy of determining the support moment which improves in the course of transition from the uniform distribution of sensors to optimal non-uniform distribution is shown. On the basis of the theory of inverse problems the method of transformation reduction at numerical differentiation of deflection functions has been studied. For engineering evaluation formulae of uncertainty estimate to determine a support moment of a cantilever beam at predetermined uncertainty of measurements using sensors have been obtained.