HUALONG|Tensile Stress Relaxation Testing Machine|SLL-2000
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High capacity Stress Relaxation Testing Machine SLL Series │ SLL-1000~2000 1 Introduction SLL Series High Capacity Tensile Stress Relaxation Testing Machine is used to determine stress-relaxation of metal, such as Pre-stressed concrete strand, Pre-stressed concrete bar, steel rope and so on, the specimen is deformed a given amount and decrease in stress is recorded over prolonged period of exposure at constant elevated temperature. The product accords with the relevant requirements of ASTM E328-02(2008) Standard Test Methods for Stress Relaxation Tests for Materials and Structures. Application ISO 6934-5 Steel for the pre-stressing of concrete -- Part 5: Hot-rolled steel bars with or without subsequent processing. BS 4486 Specification for hot rolled and hot rolled and processed high tensile alloy steel bars for the prestressing of concrete. JIS G3109 Steel bars for pre-stressed concrete. Why Stress Relaxation? Relaxation test data are necessary when designing most mechanically fastened joints to assure the permanent tightness of bolted or riveted assemblies, press or shrink-fit components, rolled-in tubes, etc. Other applications include predicting the decrease in the tightness of gaskets, in the hoop stress of solder less wrapped connections, in the constraining force of springs, and the stability of wire tendons in pre-stressed concrete. The ability of a material to relax at highstress concentrations such as are present at notches, inclusions, cracks, holes, fillets, etc., may be predicted from stress relaxation data. Such test data are also useful to judge the heat-treatment condition necessary for the thermal relief of residual internal stresses in forgings, castings, weldments, machined or coldworked surfaces, etc. The tests outlined in these methods are limited to conditions of approximately constant constraint and environment. The test results are highly sensitive to small changes in environmental conditions and thus require precise control of test conditions and methods. The reproducibility of data will depend on the manner with which all test conditions are controlled. The effects of aging or residual stress may significantly affect results, may variations in material composition. Features Automatic draw the real time curve of residual stress versus time, temperature versus time and relaxation rate versus time. Automatic calculate 1000 hours stress relaxation rate of the specimen. The calculation method has double logarithm option and single logarithm option and calculating data has entire data option and data at certain time option. The value of temperature reading of test specimen is displayed, monitored and recorded throughout the test duration. High precision temperature recorder attached to record the influence of room temperature variations in the force curve. Servo-controlled drive system ensures the high precision load/displacement close-loop control, besides, it has a very low noise during the whole test. Loading speed could be set arbitrarily. Selectable Constant load and constant displacement control. Can automatically calculate stress relaxation properties of the specimen and print complete test diagram. Realize digital calibration of load quickly and accurately, and has over-load protection function. Custom EXCEL report template available. The coordinate of the curves can be automatically adjusted. When the test begins, the system will automatically adjust the coordinate value. During the whole test process, the curves remain complete. The test requirements can be automatically stored, derive and reset. Data acquisition: Four different data sampling rate in different stage of test period makes the data acquisition more practical and avoid repeated sampling on the same data. Dual strain gauge are introduced into machine for constant strain rate constraint. Completely meet and exceed the requirements on standards for grip distance greater 2.4m.

Technical specifications Model Load Capacity Measuring Range Load Resolution Load Accuracy Creep of load cell Position Accuracy Horizontal Span Noise Loading Speed Temperature Accuracy Specimen Dimensions Steel Bar PC Bar PC Strand Machine Dimensions Gross Weight Load Measurement Accuracy: ±1% of reading to 1/50 of load weighing system capacity meets or exceeds the requirements of the following standards: ISO 7500-1, EN 10002-2, ASTM E4, JIS B7721. Speed Accuracy: Set speed 0.05% Max. Speed: ±1% Set speed ≥0.05% Max. Speed: ±0.5% Position measurement accuracy: ±0.01% of reading or 0.0001...