Dynamic Test Method Research Articles

Research on Dynamic and Static Test Methods for Evaluating the Poisson’s Ratio of Oriented Strand Board

In this article, dynamic method and static method of testing Poisson’s ratio of OSB (Oriented Strand Board) were proposed. Through modal and static numerical analyses, the position where the transverse stress is equal to zero was determined. The binary linear regression method was applied to express the gluing position of the strain gauge as a relational expression that depended on the length-width ratio and width-thickness ratio of the cantilever plate. Then the longitudinal and transverse Poisson’s ratios of OSB were measured by the given dynamic and static methods. In addition, the test results of OSB Poisson’s ratio were analyzed with the probability distribution of random variables. The results showed that using the proposed dynamic method and static method, the test results for longitudinal and transverse Poisson’s ratios of OSB were quite consistent, despite the gluing position of the strain gauges being different. And these OSB Poisson’s ratios were accorded with that obtained by the axial tensile method and the four-point bending method. OSB longitudinal and transverse Poisson’s ratios followed Weibull distribution.

Force measurements near a natural frequency of a measurement system using inverse filters

Accurate time-resolved force measurements for complex experimental systems are important for minimizing erroneous and misleading data. These measurements become difficult when a natural frequency of the system is in or near the expected frequency domain of the time-varying force being applied. In the cases where it is not possible to avoid this occurrence, the experimenter typically abandons the setup. This work presents an inverse filter method to compensate for the dynamic response of the measurement system. A two degree-of-freedom measurement system is used to obtain force measurements with dominant forcing frequencies above and below the first natural frequency of the system. The results show that inverse filtering can be used along with digital low pass filters to correct amplification and phase shift due to the dynamic response of the measurement system to within ±4.0 of total forcing amplitude and ±5.0∘. A simple cam follower mechanism is proposed as a method of low-frequency dynamic testing.

Simulation evaluation of dynamic characteristic identification accuracy of sliding bearing considering test error

Aiming at the dynamic characteristics test bench of sliding bearings, the dynamic model is established. Based on the forward and inverse dynamic problems of the bearing, a simulation evaluation method for the identification accuracy of the sliding bearing dynamic characteristics is proposed and the algorithm is verified. The identification errors of dynamic characteristic coefficients under different excitation frequencies are analyzed, the sensitivities of single frequency excitation method and dual-frequency excitation method to test error are contrastively analyzed, and the influence laws of dynamic characteristic identification accuracy of sliding bearing are evaluated. Based on which the traditional single frequency excitation method has been improved. The dynamic characteristic test should be carried out respectively in the low frequency range and the high frequency range. The main stiffness and cross damping are the average of two tests, the main damping is the identification value in the high frequency, and the cross stiffness is the identification value in the low frequency. That will effectively reduce the impact of test error. The obtained data and laws could support the improvement of the dynamic characteristics test method of sliding bearings and the confirmation of test parameters, thereby the accuracy of dynamic characteristics identification is improved.

Neutron-induced effects on a self-refresh DRAM

The field of radiation effects in electronics research includes unknowns for every new device, node size, and technical development. In this study, static and dynamic test methods were used to define the response of a self-refresh DRAM under neutron irradiation. The neutron-induced effects were investigated and characterised by event cross sections, soft-error rate, and bitmaps evaluations, leading to an identification of permanent and temporary stuck cells, single-bit upsets, and block errors. Block errors were identified in different patterns with dependency in the addressing order, leading to up to two thousand faulty words per event, representing a real threat from a user perspective, especially in critical applications. An analysis of the damaged cells' retention time was performed, showing a difference in the efficiency of the self-refresh mechanism and a read operation. Also, a correlation of the fault mechanism that generates both single-bit upsets and stuck bits is proposed. Post-irradiation high-temperature annealing procedures were applied, showing a recovery behaviour on the damaged cells.

Determination of mechanical properties from sharp dynamic indentation

In this study, a dynamic indentation test method based on the split Hopkinson pressure bar is proposed to obtain the dynamic parameters of Ludwik power law constitutive, namely, Young’s modulus E, strength coefficient K, and strain hardening index n by analyzing dynamic indentation load-indentation depth curve obtained from the theories relating to the Hopkinson pressure bar. The important parameters, namely, loading curvature C and transformation factor [Formula: see text], are invoked to examine the dynamic indentation response results in a wide range of target material parameters. Finite element calculation results are processed through simulation of dynamic indentation response with broad material parameters. Furthermore, the analytical method is used to fit simulation results to obtain the analytical equations for elastic–plastic parameters and curvature parameters for the subsequent analysis. The analytical equation of forward model to predict dynamic indentation response parameter–loading curvature C of a known material is proposed. Then, the elastic–plastic parameters of unknown materials (according to Ludwik power law) are obtained by substituting the dynamic indentation response parameters into an inverse analytical equation under the two types of half-cone angle indenters. The method is verified by other typical materials, which shows that the dynamic indentation test based on the split Hopkinson pressure bar can obtain sufficient conditions to obtain dynamic mechanical properties of target materials.

Correction to: Novel Dynamic Test Methods for Paperboard Composite Structures

Correction to: Novel Dynamic Test Methods for Paperboard Composite Structures

Nonuniform Deformation of Cell Structures Owing to Plastic Stress Wave Propagation

In cell structures, unlike in dense bodies, nonuniform deformation occurs from the impact end, even at velocities in the order of tens to hundreds of meters per second. In this study, we experimentally examine the nonuniform deformation mechanism of cell structures. They prepared two kinds of specimens: nickel foam (Ni foam) and silicone-rubber-filled nickel foam (Ni/silicone foam). As a dynamic and impact test method (compression velocity of 20 m/s or more), we used a dynamic and impact load-measuring apparatus with opposite load cells to evaluate the loads on both ends of the specimen in one test. At compression velocities of 20 m/s or less, no nonuniform deformations were observed in the Ni foam and the Ni/silicone foam, and the loads on the impact and the fixed ends achieved force equilibrium. The Ni foam showed no change with an increasing strain rate, and the Ni/silicone foam showed a strong strain rate dependence of the flow stress. At a compression velocity of approximately 26 m/s, the loads differed at the two ends of the Ni/silicone foam, and we observed nonuniform deformation from the impact end. The results of the visualization of the load and deformation behavior obtained from both ends of the specimen revealed that the velocity of the plastic stress wave and the length of the specimens are important for nonuniform deformation.

Development of contactless dynamic spindle testing using an eddy current brake

It is important to determine the dynamic stiffness of machine tools in terms of chatter vibration. Although a hammering test is widely used to measure the dynamic stiffness, it is difficult to measure a moving object at high speed because the method requires direct contact. In particular, the dynamic stiffness of milling spindles that can rotate at high speed changes considerably between the resting and rotating states. Therefore, it is essential to develop a contactless dynamic spindle test (CDST) method. Although a few CDST methods have been proposed, a conclusive method has not yet been established because of the problem of convenience. The present study proposes a novel CDST method that uses the concept of an eddy current brake. The proposed method offers advantages in that it does not require a power supply or external control, although the excitation frequency depends on the rotation speed. The present paper first introduces the principle of the proposed method. Next, the measurement results obtained by a conventional hammering test and those obtained by the proposed method are compared in order to confirm the reliability and effectiveness for an actual milling spindle.

Dynamic testing and numerical simulation of human-induced vibration of cantilevered floor with tuned mass dampers

The vibration control of a cantilevered floor with tuned mass dampers (TMDs) was investigated using dynamic testing and numerical simulation methods to better satisfy the structural serviceability requirement. The human-induced vibration response under walking and running conditions were firstly presented based on a series of dynamic testing with a single pedestrian and groups of pedestrians. A fast-evaluated frequency response function (FRF) method suggested by AISC Design Guide 11 was also used to evaluate the vibration response and further verified by the dynamic testing. A passive TMDs system was applied to reduce the vibration response; the vibration control of the cantilevered floor with TMDs was also evaluated by the dynamic testing with a single pedestrian and groups of pedestrians. The results showed that the maximum acceleration response of the cantilevered floor under the running load exceeded the limit, which was on average nine times that of the values under the walking condition. The FRF method could provide a fast and conservative vibration evaluation, in which the maximum acceleration response was 26% higher than that from dynamic testing. The acceleration response was significantly reduced with a maximum reduction effect of 64% after the installation of TMDs, resulting in satisfactory vibration serviceability of the cantilevered floor; the numerical simulation of that agreed well with the dynamic testing results. The vibration control of the cantilevered floor as a case study can serve as reference for the application of TMDs.

An investigation of dynamic ulnar impingement after the Darrach procedure with ultrasonography

Dynamic ulnar impingement is a common and painful symptom after the Darrach procedure. However, the current detection method with static radiographs often falls short of examining the dynamically symptomatic wrists. We, therefore, investigate the utility of ultrasonography to assess dynamic ulnar impingement. In this cross-sectional study, 20 patients, with 22 wrists, who had undergone the Darrach procedure were evaluated at a mean of 55 months (range, 25–171) from the index procedure. Real-time ultrasonographic imaging in the axial plane of the bone and soft tissue was performed during three different dynamic testing methods, including weight-stressed (WS), pronation-supination (PS), and forceful fist clenching (FC), to investigate ulnar impingement. Dynamic radiographs were obtained for comparison. Clinical outcomes were evaluated with grip strength and patient-reported outcomes including pain in daily activities on a numeric rating scale (NRS), the Patient-Rated Wrist Evaluation (PRWE), and the Quick Disability of the Arm, Shoulder and Hand (QDASH). Ultrasonographic ulnar impingement found during PS method was associated with worse pain and function, yet impingement diagnosed with dynamic radiographs or ultrasonography with WS and FC method was not associated with worse outcomes. While radiographic impingement was found in a total of 12 wrists (55%), ultrasonography with the WS and PS method revealed true bone contact in only 2 (9%) and 4 (18%) of the wrists, respectively. The addition of ultrasonography may be valuable in follow-up evaluations after the Darrach procedure.

16. Evaluation of the cage subsidence performance of three porous lateral cage designs

<h3>BACKGROUND CONTEXT</h3> Interbody cage subsidence remains a major complication after lumbar spine fusion surgery, particularly in lateral or other procedures that rely on indirect decompression. Porous cages are believed to reduce the risk of cage subsidence. Multiple porous cage designs exist, including 3D printed (3DP) titanium cages with body lattice and microporous endplates, 3DP titanium cages with a truss structure, and PEEK cages with surface porosity. Currently, there is a lack of carefully-controlled biomechanics studies to evaluate their relative performance. <h3>PURPOSE</h3> To evaluate the resistance to subsidence of three representative porous cage designs using ASTM standardized testing methods, as well as clinically relevant dynamic subsidence testing methods. <h3>STUDY DESIGN/SETTING</h3> Mechanical testing using foam blocks. <h3>PATIENT SAMPLE</h3> Three porous cage designs were included: a 3DP cage with stress-optimized body lattice and microporous endplates (stress-optimized titanium cage), a 3DP titanium cage with truss structure (truss titanium cage) and a PEEK cage with surface porosity (porous PEEK cage). All cage designs have the similar dimensions. N=5 testing constructs were used per cage design/loading mode. For titanium cages, one single cage was reused for all constructs. For PEEK cages, a new cage was used in each construct. <h3>OUTCOME MEASURES</h3> For ASTM F2267 static subsidence testing, the block stiffness at the implant-foam interface was reported. The greater the block stiffness, the more force was required to generate the same displacement. For the clinically relevant dynamic subsidence testing, the post-test subsidence displacement was reported, measured as the amount of displacement that each cage sank into the test block surface after a simulated 3-month period of physiologically relevant loading. <h3>METHODS</h3> Static subsidence testing per the ASTM F2267 standard, and novel dynamic subsidence testing, consisting of a physiologically relevant cyclic compressive load, were performed for each cage design to evaluate subsidence performance. Surface-conforming polyurethane foam test blocks that simulated the adjacent vertebral bodies were used in both the static and dynamic subsidence tests. All testing was performed on a calibrated servohydraulic load frame. Testing results were compared between three designs using one-way ANOVA with Bonferroni correction for post-hoc analysis. <h3>RESULTS</h3> In ASTM F2267 static compression testing, the stress-optimized titanium cage showed a significantly greater (27%) block stiffness of 2690.9 ± 92.7 N/mm than that of the truss titanium cage (2118.3 ± 19.9 N/mm, p<0.001), as well as 17.7% greater than that of the porous PEEK cage (2284.7 ± 64.5 N/mm, p=0.001). The porous PEEK cage also significantly outperformed the truss titanium cage (p=0.001) by 8%. In the clinically relevant dynamic subsidence testing, the truss Ti-cage showed the greatest amount of subsidence displacement of 0.141±0.007mm, significantly greater than that of the stress-optimized titanium cage by 153.3% (0.056±0.008mm, p<0.001) and that of the porous PEEK cage by 65.6% (0.085±0.004mm, p<0.001). The stress-optimized titanium cage showed a significantly lower subsidence displacement than that of the porous PEEK (p<0.001) by 34.6%. <h3>CONCLUSIONS</h3> Despite the common conception that porous cage design can reduce the risk of subsidence, the specific design rationale is worthy of rigorous investigation. Under the ASTM F2267 standard static subsidence testing and clinically relevant dynamic subsidence testing conditions, a 3DP titanium cage with a stress-optimized body lattice and microporous endplates showed the best subsidence performance, followed by the porous PEEK cage, and then the 3DP truss titanium cage design. <h3>FDA DEVICE/DRUG STATUS</h3> Modulus XLIF (Approved for this indication), Cohere XLIF (Approved for this indication), LATERAL SPINE TRUSS SYSTEM (Approved for this indication)

Study of the Stability of Palletized Cargo by Dynamic Test Method Performed on Laboratory Test Bench

The paper presents a method and results of experimental testing of the stability of palletized cargo wrapped in stretch film in laboratory conditions and methods and parameterization of its application for proper cargo securing. Reduction of stretch film consumption is also significant for sustainable transport. It will contribute to the minimization of costs on a micro-scale (manufacturers and shippers) and a macro scale—a significant reduction in pollution of the environment and gas emissions by reducing stretch film production. The experiments have been performed following the requirements of EUMOS 40509 and 40511 standards. The proposed method of testing the stability of palletized cargo is based on tests performed on a laboratory test bench using FEF-200 sensors. The results of conducted experiments demonstrated that the selection of a proper stretch film and a cargo wrapping model could significantly reduce the risk of cargo damage through increasing cargo stabilizing forces and, at the same time, reducing stretch film consumption. The developed method can significantly reduce the cost of securing and concurrently assure required cargo security. This directly impacts the safety of all participants in the transport process in supply chains.

Experimental study on bending properties of cross-laminated timber-bamboo composites

Using bamboo and timber to manufacture cross-laminated timber-bamboo (CLTB) composites could utilize the advantages of two material to improve the mechanical properties and expand the raw material source of cross-laminated timber (CLT). To explore the feasibility of using engineered bamboo as CLT lamination, the rolling shear properties of two bamboo scrimbers and one bamboo plywood were evaluated. Two types of CLTB specimens, using bamboo scrimber as transverse layer or as both transverse layer and the outermost longitudinal layer, were developed in this study. The bending properties of CLTB and generic Spruce-pine-fir (SPF) CLT specimens were evaluated by dynamic tests and third-point bending tests, respectively. The shear analogy method was employed to calculate the apparent bending stiffness of CLT/CLTB specimen. The results indicated that the rolling shear modulus and strength of bamboo scrimber (group RB(F)-4.5) were 92.81% and 98.64% higher than those of bamboo plywood, respectively, and were 330.19% and 121.13% higher than those of SPF dimension lumber, respectively. The CLTB specimens, group BWBWB, had 23.69% and 60.50% higher apparent bending modulus and peak load than those of generic SPF CLT specimens. Most of the CLTB bending specimens had main failure mode of tensile failure in the bottom layer which replaced rolling shear failure in transverse bamboo scrimber layer. The apparent bending stiffness values of CLT/CLTB specimens obtained from dynamic test and shear analogy method were in good agreement with the static experimental values. The results presented in this paper can provide fundamental basis for supporting the potential engineering application of CLT panel products fabricated with bamboo scrimber.

An Automated Testing Framework for Gesture Recognition System using Dynamic Image Pattern Generation with Augmentation

In the field of information technology, the gesture recognition system plays a very essential role. As it has achieved vast importance, it is mandatory to test the recognition system to ensure the quality of the system by identifying the bugs in the software. In our research, we suggested a dynamic testing method for gesture recognition software. using dynamic image pattern generation with augmentation. The automated software testing framework is a set of processes to create new test cases for properly testing a image processing software. The research intention for generate automated testing cases by following a standard process which helps to increase the performance and efficiency of the gesture recognition system. We have built the framework to give proper testing and give result (accuracy and defect) for which gesture recognition system already in the market. our research, the team strongly following and adding two software testing standard. First one is ISO/IEC/IEEE/291129-3 to define the process for testing software. And the second one is ISO/IEC/IEEE/291129-5 to implement the techniques for software testing. We proposed this framework with major five parameters by noise, rotation, background, contrast, and scale. Which are the most use with every gesture recognition system. Our developed framework’s phase is used to generate new testing cases based on the existing gesture recognition system’s data. There are we work with five systems, commonly with the gesture recognition for experiments. We provide the testing report with total accuracy and defect by comparing existing well-known system’s data. At the final result, our system suggested an analysis report based on the testing result. And tell what are the improvement needs for the existing system to consider noised images or different scaled images to build a robust system.&#x0D; GUB JOURNAL OF SCIENCE AND ENGINEERING, Vol 7, Dec 2020 P 42-50

Determination of Carbon Steel Dynamic Properties

Taylor anvil test is one of the dynamic test method in which we can determine the dependences of strain, strain rate, temperature on flow stress. With this method, we can determine in each cross sec-tion or along axial section of the test specimen conditions under different states of stress, strain, strain rates and subsequent changes in the microstructure of the material. This paper describes the experimental results of the Taylor anvil test (TAT) for TRISTAL carbon steel. The experiment was performed on a TAT test facility in the Laboratory of High Strain Rates at the Faculty of Mechanical Engineering in Brno. For simulation of the mechanical behavior of TRISTAL steel under dynamic load condition was used LS DYNA 3D. This paper also contains the results of the Johnson-Cook constitutive equation for TRISTAL steel. The simulation results are compared with the experimental TAT results.

COMPARISON BETWEEN THE RESULTS OF THE PILE BEARING CAPACITY ANALYSIS BASED ON EMPIRICAL METHOD AND FINITE ELEMENT METHOD USING THE RESULTS OF DYNAMIC ANALYSIS ON THE FIELD

There are many methods for calculating the bearing capacity of a pile foundation. The problem is finding the most representative method for analysis dynamic load testing (PDA) results in the field. This study only covers the areas of West Surabaya and North Surabaya. The method used to analyse the bearing capacity of the pile foundation in this study is the empirical method, namely the Schmertmann, Meyerhof, and L. Decourt method and the finite element method (FEM.). This research only for calculating the bearing capacity of precast pile foundations. The initial stage of the research was to collect soil survey data in the form of N-SPT boring logs and PDA test results in the area. Then the calculation analysis is carried out using the empirical method and FEM, which will be compared with the PDA results. FEM analysis uses dynamic load with pile-driving modelling, which is similar to PDA testing. After comparison, the researchers find some ratios for each calculation method and results of PDAs in the field of study. This study indicates that the most representative method for PDA results in West Surabaya is the Meyerhof method. For the North Surabaya area, these methods have not shown expected results of PDA results in the field

Research on Dynamic Response Time Test System and Method of Reactive Power Compensation Device

In the actual enterprise production and inspection process, we found that there is a certain error in the dynamic response time detection method specified in the standard. For the fast response compensation device, the deviation is large, so it is urgent to study and improve the dynamic response test method. Especially for the dynamic reactive power compensation device with millisecond fast response, its input mode, the processing speed of the controller and the calculation method will affect the dynamic response time. In order to solve the shortcomings of the existing technology, this paper proposes a dynamic response time test system and method for reactive power compensation device. By introducing electronic load to generate periodic impulse current waveform, it can not only avoid the impact transient problem of inductive load, but also generate intermittent impulse current waveform, which is convenient to test the dynamic response time after switching off, which greatly improves the test accuracy. The simulation results show that the method can test the dynamic response time of tens of milliseconds more effectively and quickly.

Studies on Bearing Characteristic of Open-Ended and Close-Ended Pipe Piles under High-Speed Railway Loadings

The pile foundation under a high-speed railway (HSR) not only bears the self-weight of the superstructure, but also bears a long-term vertical periodic load during its service. In this study, a large-scale vertical dynamic load test and particle flow numerical simulation method were adopted to investigate the axial cyclic performances of open piles in sand. The results from the dynamic test show that under a dynamic load with cyclic load ratios of 0.1 and 0.2, the surface displacement of the pile decays rapidly as the pile distance increases. Moreover, the higher the vibration amplitude and frequency, the larger the surface displacement. The influence range of the soil around the pile is approximately six times of the pile diameter. It is also found that the external frictional resistance of the upper part of the pile decreases, whereas that of the middle part increases. In addition, the internal friction resistance of the lower part of the pile decreases and gradually stabilizes after approximately 200 cycles. The simulation results show that the influence range of the pile on the surrounding soil is approximately 5–8 times the diameter of the pile under the action of dynamic loading; the vertical displacement of the pile mainly occurs at the beginning of the cycles. The total settlement of the pile foundation increases with an increase in the cyclic load ratio. With an increase in the cycle period, the friction resistance values on the outside of the pile and middle part significantly decrease and increase, respectively. After 10 cycles, the resistance gradually stabilizes, and no evident changes in the internal friction resistance of the pile are observed.

Structural optimization design for beam position monitor support of High Energy Photon Source

Based on thermal stability and vibration stability, an ultra stability structure of rigid support is designed and optimized. Through the finite element modal analysis of ANSYS, the thermal expansion variation and the characteristic frequency of the support is verified. The support is fixated to the ground by using the method of concrete grouting and then the characteristic frequency is tested. The test results show that the characteristic frequency of the support reaches up to 61.9 Hz and the vibration amplitude is less than 30 nm, both of which meet the design requirements. Finally, the method of dynamic stiffness testing is adopted to obtain the stiffness value of the concrete grouting, and the accuracy of the optimization results of the support is further verified.

A New Dynamic Simulation Test Method of Intelligent Electricity Metering System

Electricity metering is the core supporting technology for realizing accurate perception of electricity consumption, reasonable dispatching of power grids, rapid market response, diversified charging and new forms of electricity marketing. However, due to the significant differences in the actual metering environment, the operation of the electricity metering and information collection system is unstable, showing many problems such as unsuccessful parameter delivery and low acquisition success rate, which severely restricts the development of smart grid two-way interactive technology and the realization of smart electricity consumption in the last mile. There is an urgent need for a reliable and accurate dynamic simulation and systematic testing method to realize the reproduction and testing of various field faults. In this paper, we propose a new type of dynamic simulation test method for intelligent electricity metering system, which can realize the performance test, fault dynamic simulation, location and recovery of each functional unit of the master station, collection terminal and smart meter. Through experimental testing, our dynamic simulation test methods can realize the rapid recurrence of on-site problems, improve the high reliability and normal operation of the electric energy metering information collection system.