Dynamic Test Method Research Articles

Bone plate-screw constructs for osteosynthesis - recommendations for standardized mechanical torsion and bending tests.

This paper follows up on a recent systematic review of test methods and parameters for biomechanical testing of bone plates and it is the first study that contains recommendations for standardized mechanical testing of bone plate-screw constructs for osteosynthesis. Following the testing philosophy of ASTM F382 and ISO 9585, we have developed standardized quasi-static and dynamic testing methods for straight linear and anatomically shaped plates, including locked type and conventional systems. The test specification comprises torsion and bending tests along the implant axis and therefore modifies and extends the methods proposed by ASTM F382. We present specific test setups in order to determine product-specific characteristics of the mechanical construct, consisting of the bone plate with corresponding screws (such as construct stiffness, yield strength, ultimate strength and fatigue properties) under the condition that it is rigidly fixed to "healthy bone". We also address specific testing requirements that are important for the purpose of standardization, such as the positioning of the construct for testing or the number of screws in the diaphysis and metaphysis. Finally, we define the outcome parameters and associated failure criteria related to quasi-static and dynamic testing for comparative purposes. This paper does not intend to replace biomechanical testing of those devices under physiological loading conditions.

Актуализация систематизации методов динамических испытаний ограждений предохранительных инвентарных

Актуализация систематизации методов динамических испытаний ограждений предохранительных инвентарных

10.32: Experimental study on high temperature elastic modulus of China made high strength structural steel

ABSTRACTHigh strength structural steel (HSSS) has better economic and environmental benefits than mild structural steel, and becomes more popular in the building construction projects. The current codes for fire safety design of steel structures is mainly developed based on the test data from mild structural steel and might be not applicable to the high strength structural steel. This paper reports an experimental study on the high temperature elastic modulus of China made high strength structural steel. Both static and dynamic test methods were used to determine the elastic modulus of Q550, Q690 and Q890 China grade steel at temperatures ranging from 20 °C to 800 °C. Suspended coupling bending resonance method was used to measure the dynamic elastic modulus. The reduction factors of elastic modulus from test data were compared with the reduction factors determined by current codes, including the Chinese code CECS200, the Eurocode 3, the American code AISC and the Austrian code AS4100, and by other researchers. The study found that unlike the static reduction factors (reduction factors determined by the static method) the dynamic reduction factors are not sensitive to the steel grade. The static elastic modulus is greater than the dynamic elastic modulus at low temperatures and is less than the dynamic modulus at high temperatures. Both the static and dynamic reduction factors of HSSS are greater than the elastic modulus reduction factors employed by the current codes. Design equation for dynamic elastic modulus of HSSS was derived from curve‐fitting of the test data.

The prevalence of growth hormone deficiency in survivors of subarachnoid haemorrhage: results from a large single centre study

ObjectiveThe variation in reported prevalence of growth hormone deficiency (GHD) post subarachnoid haemorrhage (SAH) is mainly due to methodological heterogeneity. We report on the prevalence of GHD in a large cohort of patients following SAH, when dynamic and confirmatory pituitary hormone testing methods are systematically employed.DesignIn this cross-sectional study, pituitary function was assessed in 100 patients following SAH. Baseline pituitary hormonal profile measurement and glucagon stimulation testing (GST) was carried out in all patients. Isolated GHD was confirmed with an Arginine stimulation test and ACTH deficiency was confirmed with a short synacthen test.ResultsThe prevalence of hypopituitarism in our cohort was 19% and the prevalence of GHD was 14%. There was no association between GHD and the clinical or radiological severity of SAH at presentation, treatment modality, age, or occurrence of vasospasm. There were statistically significant differences in terms of Glasgow Outcome Scale (GOS; p = 0.03) between patients diagnosed with GHD and those without. Significant inverse correlations between GH peak on GST with body mass index (BMI) and waist hip ratio (WHR) was also noted (p < 0.0001 and p < 0.0001 respectively).ConclusionUsing the current testing protocol, the prevalence of GHD detected in our cohort was 14%. It is unclear if the BMI and WHR difference observed is truly due to GHD or confounded by the endocrine tests used in this protocol. There is possibly an association between the development of GHD and worse GOS score. Routine endocrine screening of all SAH survivors with dynamic tests is time consuming and may subject many patients to unnecessary side-effects. Furthermore the degree of clinical benefit derived from growth hormone replacement in this patient group, remains unclear. Increased understanding of the most appropriate testing methodology in this patient group and more importantly which SAH survivors would derive most benefit from GHD screening is required.

Geopolymerization Ability of Natural and Secondary Raw Materials by Solubility Test in Alkaline Media

The extent of the dissolution of aluminosilicate compounds is crucial, since the amount of Si and Al initially dissolved is essential for the following polycondensation and can strongly influence physical and mechanical performances of the final product. In order to set up a method to test the ability of a material to react in alkaline media, different aluminosilicate sources have been selected: a mineral resource (a zeolitized tuff), an industrial by product (silt from washing process of construction and demolition wastes), a heat treated clay sediment and a calcined clay (metakaolin). Two test methods, static and dynamic, have been applied to evaluate the attitude of a silicoaluminate precursor to give a geopolymerization reaction. In particular, a fixed amount of precursor was put into contact with a alkaline solution under continuous stirring or in static conditions at 60 °C for fixed times. The dynamic test method seems to be more suitable, since it is faster and requires lower amounts of reactants (solution). Moreover, the dynamic test provides a reactivity sequence (ordered from the more to the less reactive precursor) metakaolin &gt; treated clay sediment &gt; zeolitized tuff ≈ silt both for Si and Al release, which is coherent with the performances of geopolymers obtained by using the above precursors.

Application of a vibration damping technique in characterizing mechanical properties of chicken meat batters modified with amaranth

Thermal analysis, texture profile analysis, water holding capacity and dynamic mechanical testing methods were used for study of the physico-chemical and mechanical properties of the model chicken meat batters modified by the addition of amaranth flour. It was found that the addition of the amaranth effectively modified and improved their textural and nutritional properties. Further, the addition of calcium dihydrogen phosphate to the complex meat batter was shown to enhance formation of the creation of the three dimensional gel networks during protein denaturation, which resulted in increased tenderness of the product, as was demonstrated by decreased hardness, toughness and gumminess of the chicken batters with the increase of amaranth concentration. These findings were supported by dynamic mechanical vibration testing experiments and by increased water holding capacity. After amaranth flour addition, the observed frequency dependence of the measured damping transfer function of the tested samples showed typical viscoelastic behaviour rather than pure elastic behaviour. The first resonance peak frequency shifted from 200 Hz for unmodified chicken batter to 120 Hz for batter with 1 wt% amaranth concentration and 0.45 wt% calcium dihydrogen phosphate. Formation of a hydrocolloid gel structure was confirmed by thermal analysis experiments, which showed decreased DTA protein denaturation temperature peak position from 101.3 °C for the unmodified batter to 90.6 °C for batter with 2 wt% amaranth. Interestingly, after addition of a Ca2+ crosslinking agent into the matrix, thermal resistance of the gel phase increased, which was reflected by the increased latter denaturation peak position from 93.7 °C (for 1.5 wt% amaranth concentration chicken meat batters without calcium dihydrogen phosphate) to 108.8 °C for 0.45 wt% crosslinking agent calcium dihydrogen phosphate and 1.5 wt% amaranth concentration chicken meat batters.

Mechanical Properties of the HL-LHC 11 T Nb3Sn Magnet Constituent Materials

A test campaign was launched to determine the mechanical properties of the High Luminosity-Large Hadron Collider (HL-LHC) 11 T Nb3Sn magnet components. The results can be used to accurately represent the mechanical properties in finite element models that predict the stress and strain distribution in these magnets. Particular attention is paid to anisotropic mechanical behavior of the different magnet materials. Static and dynamic test methods have been applied for determining elastic materials’ behavior, and highly accurate Young's moduli are obtained with the nondestructive dynamic methods resonance and impulse excitation at ambient temperature and during in situ heat cycles.

Fatigue and Fracture Reliability of Shell-Mimetic PE/TiO2 Nanolayered Composites

Shell-mimetic (PE/TiO2)4 nanolayered composites stacked alternatively by 20 nm-thick PE layers and 55 nm-thick nanocrystalline TiO2 layers are synthesized by a combination of the layer-by-layer self-assembly and the chemical bath deposition methods. The critical cracking strain and the apparent fracture energy of the bio-mimetic nanolayered composites are determined as 0.56% and 0.98 J m−2, respectively, by the simply supported beam bending testing. Fatigue properties of the (PE/TiO2)4 nanolayered composites are evaluated by the dynamic bending testing method. The critical fatigue strain amplitude corresponding to the lowest strain amplitude for fatigue cracking of the present (PE/TiO2)4 NLCs is 0.0853%, which is much lower than the critical cracking strain (0.56%) under monotonic bending. The finding indicates that the potential fatigue threat to the long-term reliability of the bio-mimetic nanolayered composites needs to be concerned.

Investigation of the dynamic behaviour of a storage tank with different foundation types focusing on the soil‐foundation‐structure interactions using centrifuge model tests

SummaryThis paper proposes a dynamic centrifuge model test method for the accurate simulation of the behaviours of a liquid storage tank with different types of foundations during earthquakes. The method can be used to determine the actual stress conditions of a prototype storage‐tank structure. It was used in the present study to investigate the soil‐foundation‐structure interactions of a simplified storage tank under two different earthquake motions, which were simulated using a shaking table installed in a centrifuge basket. Three different types of foundations were considered, namely, a shallow foundation, a slab on the surface of the ground connected to piles and a slab with disconnected piles. The test results were organised to compare the ground surface and foundation motions, the slab of foundation and top of structure motions and the horizontal and vertical motions of the slab, respectively. These were used to establish the complex dynamic behaviours of tank models with different foundations. The effects of soil–foundation–structure interaction with three foundation conditions and two different earthquake motions are focused and some important factors, that should be considered for future designs are also discussed in this research. Copyright © 2017 John Wiley &amp; Sons, Ltd.

Methods of applying nuclear simulation technology to the dynamic site testing of digital I&C system—I: Scheme of OLVT

With a shift in technology to digital systems as the result of analog obsolescence and digital functional advantages, existing plants have begun to replace some current analog instrument and control (I&C) systems, while new plant designs fully incorporate digital systems. The requirements for dynamic site testing of digital distributed I&C system (DCS) come with the transitions from analog to digital technology because DCS have more complex structure (hardware/software/firmware), employ more complicated logic algorithms and have more dynamic interactions than the analog one. Further, the requirements are enhanced by the fact that there are several NPPs under construction each year in China, but a shortage of expert engineers and an urgency for continued construction. However, the dynamic testing methods developed for the design V&V or the factory testing cannot be applied directly in site testing because of the constraints of the conditions at site. In this paper, we generalized on-line virtual testing (OLVT) methods for site testing and expanded the application scope of OLVT to test a universal DCS system based on our experience and knowledge of site testing. An implementation scheme for OLVT is introduced to support flexible DCS-testing applications, including a structure design of OLVT, development of the DCS-testing platform and connection ways.

OOK power model based dynamic error testing for smart electricity meter

This paper formulates the dynamic error testing problem for a smart meter, with consideration and investigation of both the testing signal and the dynamic error testing method. To solve the dynamic error testing problems, the paper establishes an on-off-keying (OOK) testing dynamic current model and an OOK testing dynamic load energy (TDLE) model. Then two types of TDLE sequences and three modes of OOK testing dynamic power are proposed. In addition, a novel algorithm, which helps to solve the problem of dynamic electric energy measurement’s traceability, is derived for dynamic errors. Based on the above researches, OOK TDLE sequence generation equipment is developed and a dynamic error testing system is constructed. Using the testing system, five kinds of meters were tested in the three dynamic power modes. The test results show that the dynamic error is closely related to dynamic power mode and the measurement uncertainty is 0.38%.

Liquid and Plastic Limits of Cohesive Soil by Static and Dynamic Test Methods and Testers

Liquid and Plastic Limits of Cohesive Soil by Static and Dynamic Test Methods and Testers

Study on the Effect of Multi-Type Current Transformers Hybrid Operation on Differential Protection of the Bus Based on Dynamic Simulation

This paper analyzes characteristics of multi type current transformers hybrid operation for each branch of the bus and their effects on differential protection of the bus. By theoretically analyzing transmission characteristics of multi type current transformers and their influence factors, we study the dynamic model testing method of multi type current transformers for the bus, and design 3 kinds of testing schemes by making the equivalent model based on the field of P-level current transformer, TPY-level current transformer and electronic current transformer, and build the hybrid operation testing platform of multi type current transformers. Finally, we compare and analyze the transmission characteristics difference of multi type current transformers on the same branch and the characteristics difference of hybrid operation in two successive external faults, analyze the cause behind the differences, and put forward the corresponding improvement measures.

Application of Impact Vibration Test Method for Bridge Substructure Evaluation

The bridge foundations are constructed mainly below ground or water level. The rehabilitation of a foundation is difficult, and the results of evaluation of structural conditions are usually inaccurate. Furthermore, there are many cases that after natural disasters such as earthquakes, typhoons and floods, it is required to rapidly evaluate bridge substructure conditions for a judging decision on being able to open the bridge to traffic or not. Impact vibration test method has been developed to deal with such problems. Impact vibration test method is a non-destructive dynamic test method which allows to evaluate structural conditions of bridge substructures promptly with a good soundness. In this study, firstly, impact vibration test method, which is one of the utilizable non-destructive tests on the scouring of bridge substructure, is presented. Then, application of the test method for substructure evaluation of a bridge in Vietnam is introduced. The soundness and effectiveness of test method is also discussed.

COMPARISON OF PROPAGATION CHARACTERISTICS OF EXCITED STRESS WAVES IN PILE AND ANCHORAGE WITH BOLT SYSTEMS

Dynamic testing methods for pile systems and anchorage-with-bolt systems are similar andoften confused with each other, possibly resulting in incorrect assessment of the quality of the pileand the anchorage systems. The stress wave velocity is one of the most important parameters forevaluating the quality of dynamic tests. In this paper, the stress wave velocities in standardconcrete specimens of the free rock bolt and the different ages were a reference for comparing thestress wave velocities in a pile-and-anchor system. The tests were conducted using the low strainreflected wave method. Results indicate that the wave velocity in a pile is larger than that in thestandard samples, and that the wave velocity in an anchorage-with-bolt system is smaller than thatin a free steel bar, but larger than that in a pile and in standard samples. Wave velocities in the pileand in the standard samples were found to raise as the ages of samples increased. The wavevelocity in the anchorage-with-bolt system initially decreased as specimen age increased, butincreased with increasing specimen age afterward.

Determining the correlation between daytime and night-time road markings visibility

Road markings quality control implies conducting several different tests, of which the most significant are visibility tests comprising daytime and night-time visibility measurements by applying the static or the dynamic measuring method. Although the dynamic test method allows measuring the visibility along the entire road section and thus provides a more complete and objective evaluation of road markings quality compared to the static method, it does not measure daytime visibility, for which both the European and the national directives define the minimum requirements. The purpose of this paper is to examine the correlation between daytime and night-time visibility based on static measurements conducted on state roads in the Republic of Croatia. The correlation analysis determined that the strength of relationship between daytime and night-time visibility, is relatively weak. Despite being relatively weak, the relationship still exists, which was the reason for conducting a further analysis. In the analysis, a unique coefficient was obtained through the ratio of retroreflection value and daytime visibility value for all the measurements. The unique coefficient was basis for development of a model that will be able to calculate the daytime visibility based on the results of the dynamic measurements of road markings night-time visibility. The authors evaluated the model with a t-test and concluded that the accuracy of the model is statistically satisfactory.

Nonlinear Unsteady Aerodynamic Modeling Using Wind-Tunnel and Computational Data

Extensions to conventional aircraft aerodynamic models are required to adequately predict responses when nonlinear unsteady flight regimes are encountered, especially at high incidence angles and under maneuvering conditions. For a number of reasons, such as loss of control, both military and civilian aircraft may extend beyond normal and benign aerodynamic flight conditions. In addition, military applications may require controlled flight beyond the normal envelope, and civilian flight may require adequate recovery or prevention methods from these adverse conditions. These requirements have led to the development of more general aerodynamic modeling methods and provided the impetus for researchers to improve analytical and experimental techniques and the degree of collaboration between them. In addition to more general mathematical model structures, dynamic test methods have been designed to provide sufficient information to allow model identification. This paper summarizes research to develop a modeling methodology appropriate for modeling aircraft aerodynamics that include nonlinear unsteady behaviors using either experimental or computational test methods. This work was done at NASA Langley Research Center, primarily under the NASA Aviation Safety Program, to address aircraft loss of control, prevention, and recovery aerodynamics.

Prosta metoda badania błędów dynamicznych w pomiarach skaningowych na maszynach współrzędnościowych

Prosta metoda badania błędów dynamicznych w pomiarach skaningowych na maszynach współrzędnościowych

Dynamic tensile behaviors of AZ31B magnesium alloy processed by twin-roll casting and sequential hot rolling

The dynamic tensile behavior of twin-roll cast-rolled and hot-rolled AZ31B magnesium alloy was characterized over strain rates ranging from 0.001 to 375 s−1 at room temperature using an elaborate dynamic tensile testing method, and the relationship between its mechanical properties and microstructures. It is observed that the sheet has a strong initial basal fiber texture and mechanical twinning becomes prevalent to accommodate the high-rate deformation. The yield strength and ultimate tensile strength monotonically increase with increasing the strain rate, while the strain hardening exponent proportionally decreases with increasing the strain rate due to twinning-induced softening. The total elongation at fracture distinctly decreases as the strain rate increases under quasi-static tension, while the effect of strain rate on the total elongation is not distinct under dynamic tension. Fractographic analysis using a scanning electron microscope reveals that the fracture is a mixed mode of ductile and brittle fracture.

RESEARCH ON DYNAMIC SIMILARITY MODEL TEST OF DAMAGE DETECTION FOR TRANSMISSION TOWER

In order to explore the dynamic similarity model test method different from atmospheric boundary layer wind tunnel and shaking table model test, in accordance with dynamic similar theory, an elastic model of a transmission tower with 1/35 scale and 5.2m height has been designed and manufactured with thin-walled circular pipes of high-density polyethylene. The model has been tested in the laboratory for time and frequency domain responses under suddenly unloading, essential dynamic characteristic of the scale model is also analysed and compared with that of its prototype tower, the dynamic similarity of the two is confirmed. By the mathematical deduction of Wigner-Ville Distribution (WVD) signal terms of structural free vibration response, the new damage detection index with clear physical signification is forwarded for damage detection for transmission tower, the damage detection test of the scale model of transmission tower is then carried out, totally three damage cases, related with chord rod weakening, flank rods failure, different damage degrees and positions, are tested to validate the proposed damage detection index.