Range Of Dynamic Tests Research Articles

Effect of the strain rate on the deformation mechanisms of TWIP-type steel

This paper describes the influence of the strain rate on the microstructure of X55MnAl25-5 steel from the group of high-manganese steels exhibiting the twinning-induced plasticity effect. The tests were carried out at a wide range of strain rates, starting with static tensile tests where the appropriate strain rates were 0.005 s−1, and ending with tests using a flywheel machine at strain rates of 1830 s−1 and 4650 s−1. The increase in the applied strain rate on the example of the tested steel results in hardening. Evolutionary changes leading to the predominance of dislocation slipping over the twinning are observed in the microstructure under static deformation conditions. The increase in the intensity of twinning with the simultaneous decrease in the mobility of dislocations progresses as the strain rate increases. The microstructure evolution was characterized using light optical microscopy and scanning electron microscopy, including electron backscatter diffraction. The qualitative analysis of the deformation twins was performed. For the lowest strain rate, 5·10−4 s−1, deformation twins appear in a single twinning system, while increasing the strain rate leads to the activation of multiple twinning systems. Proceeding to the range of dynamic tests reveals an increase in the participation of the twinning mechanism in the deformation of the examined steel. With an increasing strain rate, the effect of texture on the twinning process activity decreases. Based on the obtained results, a diagram was elaborated that presents the microstructural changes which take place in X55MnAl25-5 steel after deformation under static and dynamic tensile conditions in graphical form.

Design and fabrication of a novel MEMS piezoelectric hydrophone

Hydrophone, serving as a part of sonar, has a significant effect on the performance of acoustic sensors such as frequency characteristics and sensitivity, however, some limitation such as high cost and complexity in SOI manufacturing technique hinder the industrial application of hydrophones. Therefore, a novel Micro-Electro-Mechanical Systems (MEMS) piezoelectric vector hydrophone based on PZT (lead zirconate titanate) film has been adopted in obtaining vector information of underwater sound field. The piezoelectric hydrophone sensor was analyzed, designed and fabricated with PZT-on-Si substrate, and the structure consists of a four-cantilevers and an acoustics columnar cilium fixed on the center micro mass. According to the simulation results, the piezoelectric films are optimally distributed at the tip of the four beams, where the maximum strain locates. Finally, the piezoelectric vector hydrophone was characterized by comparative calibration experiments in a standing wave bucket. This passive MEMS piezoelectric hydrophone has the characteristics of receiving sensitivity with −189.3 dB at 920 Hz (0dB = 1 V/μPa) and a typical directional pattern of "8" shape, low noise output and high dynamic test range, which is suitable for high precision passive underwater detection.

An Automated Laboratory Method for Measuring CO2 Emissions from Soils

Core Ideas A GC method to measure soil CO2 emission was developed and compared with Solvita CO2 burst method. A strong exponential relationship between Solvita and GC method was observed. CO2 emissions from soils increased with drying temperature to a maximum at 65°C. The data presented highlight the narrow linear range of the Solvita method. The standardized procedure increased rate of analysis and reduced costs. A gas chromatography (GC) headspace method was developed for soil microbial respiration (CO2 emission) analysis after a 24‐h incubation of a rewetted soil. The GC method was compared with the Solvita CO2 burst method by analyzing 18 different soils that were air‐dried (22°C) or dried at 45, 65, and 105°C for 24 h before rewetting. A strong exponential relationship between the Solvita color number and GC headspace CO2–C emission was observed. Compared with air‐dried soils, drying at 65°C led to increased CO2 emission and reduced variation among sample replicates, while drying at 105°C led to a reduction in CO2 emission and an increase in variability. The GC method does not require sample dilution, provides data that is highly correlated to the Solvita method, and has a wider dynamic test range than the Solvita method. The developed GC method could be adapted to automation for commercial laboratory use.

English

Proof and trial activity in a dynamic test range is a complex, sensitive, and herculean activity. It is a system comprising critical functions that accept various armament inputs and produces proof results as output, processing various critical data and sensitive activities in between. Automation of the existing system is a step for reliable, secure, smooth operation and easy maintainability of the system that makes it synchronized with the latest development of range technology. Understanding the flow of data through these functions requires extensive study to realize different inter-linked activities involved with the functions of this system. This paper presents the flow of activities in the automation of dynamic test range of Proof & Experimental Establishment through context level diagram, process flow diagram, data flow diagram, and entity-relationship diagram. Realization of armament integrated management system will be through resilient and high bandwidth network backbone which is a part of this paper. Cloud computing is the latest development in the information technology. This paper also analyses the appropriate model of cloud computing for porting the system in the cloud. Science Journal, Vol. 64, No. 6, November 2014, pp.524-529, DOI:http://dx.doi.org/10.14429/dsj.64.8113

Non-null annular subaperture stitching interferometry for steep aspheric measurement.

A non-null annular subaperture stitching interferometry (NASSI), combining the subaperture stitching ideal and non-null test method, is proposed for steep aspheric testing. Compared with standard annular subaperture stitching interferometry (ASSI), a partial null lens (PNL) is employed as an alternative to the transmission sphere, to generate different aspherical wavefronts as the references. The coverage subaperture number would be reduced greatly for the better performance of aspherical wavefronts in matching the local slope of aspheric surfaces. In this way, relatively large overlapping areas can be obtained for adjustment errors correction while the error accumulation would be decreased. With the reverse optimization reconstruction (ROR) method for retrace error correction, the figure error of each subaperture can be retrieved accurately. Therefore, the testing accuracy and efficiency are thus increased. The dynamic test range is extended as well. A numerical simulation exhibits the comparison of the performance of the NASSI and standard ASSI, which demonstrates the high accuracy of the NASSI in testing steep aspheric. Experimental results of NASSI are shown to be in good agreement with those of the Zygo interferometer.

Virtual traumatology of pregnant women: The PRegnant car Occupant Model for Impact Simulations (PROMIS)

This study report documents the development of a finite element (FE) model for analyzing trauma in pregnant women involved in road accidents and help the design of a specific safety device. The model is representative of a 50th percentile pregnant woman at 26 weeks of pregnancy in sitting position. To achieve this, the HUMOS 2 model, which has been validated in a wide range of dynamic tests, was scaled to the morphology of a woman in the 50th percentile and coupled with a model of gravid uterus. During scaling, special attention was paid to the pelvic region which is known to differ considerably in morphological terms between men and women. The gravid uterus model includes a placenta, a fetus, uterosacral ligaments and the amniotic fluid by means of fluid structure interaction formulation. The uterus and the female model were coupled using an original method whereby the growth of an uterus was simulated to compress the abdominal organs in a realistic manner. The model was validated based on experimental tests described in the literature. Additional tests based on abdominal loadings with a seatbelt on Post Mortem Human Surrogates (PMHS) coupled to silicone uterus were also performed.Results highlighted the role of the possible interaction of the fetus in the pregnant woman abdominal response. Experimental corridors taking into account the presence of this fetus could therefore be proposed.