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Steel strand tensile stress relaxation testing machine

Steel strand tensile stress relaxation testing machine

Model: LW-R series, Computer control, 300KN, 500KN

Computer controlled steel strand tensile stress relaxation testing machine mainly used to check the prestressing steel material relaxation performance. This machine is use mechanical mode loading, computer control to complete the test. PC with control card to realize real time data collection, display and analysis, automatic generate the test curve. 

Mainly used for pre-stressed steel, steel strand, PC steel rod etc., material, tensile stress relaxation test, constant temperature stress relaxtion test, relaxation test period over than 1000 hours. 
Constant relaxtion test is at provided temperature (20℃士2℃), keep the sample at certain length (L0+△L0), from original F0 to check the load change on sample. 
The relaxation period 120h ~ 1000h free setting. 
Conform with: ASTM E328 Standard Test Methods for Stress Relaxation Tests for Materials and Structures; EN 10319-1, Metallic materials. Tensile stress relaxation testing. Procedure for testing machines; ISO 15630-3ISO 6394-4 etc., 


General introduction

LW-300R/500R computer controlled steel strand tensile stress relaxation testing machine mainly used to check the prestressing steel material relaxation performance. This machine is use mechanical mode loading, computer control to complete the test. PC with control card to realize real time data collection, display and analysis, automatic generate the test curve. 

Frame is horizontal structure, suitable for long test sample (large than 2m). This product is design according GB/T 16491-2008, GB/T 2611. GB/T 6825 etc., standard.


Mainly used for pre-stressed steel, steel strand, PC steel rod etc., material, tensile stress relaxation test, constant temperature stress relaxtion test, relaxation test period over than 1000 hours. 
Constant relaxtion test is at provided temperature (20℃士2℃), keep the sample at certain length (L0+△L0), from original F0 to check the load change on sample. 

The relaxation period 120h ~ 1000h free setting. 

Application:
Widely used for industrial application, factory quality control, science and research institute, QC &QA college student training, education institute, testing and inspection center, laboratories, construction company, aerospace, mechanical production, electric appliance fields. 
ASTM E328 Standard Test Methods for Stress Relaxation Tests for Materials and Structures

GB/T 10120 Metallic materials-tensile stress relaxation.

ISO 15630-3, Steel for the reinforcement and prestressing of concrete. Test methods - Part 3: Prestressing steel

ISO 6394-4, Steel for the prestressing of concrete; part 3: quenched and tempered wire

EN 10319-1, Metallic materials. Tensile stress relaxation testing. Procedure for testing machines

JIS Z2276. 

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Key Features

  • Main features
  • High-precision Servo Control
  • Standard

1, Original force, original force holding, zero time keep original total strain, standard gauge constant, constant record load, temperature, relaxation rate, curve etc., 
2, Relaxation test time (start time, certain time, interval time, constant record, relaxation time≥1000h. 
3, conform with standard: ISO 15630-3, ISO 6394-4, EN 10319-1, ASTM E328, JIS Z2276. 
4, Four columns, high stiffness, high reliability. 
5, High precision load cell, AC servo motor and driving system. 
6, Big range test speed range for free setting. 

Adopts closed-loop servo control technology, achieving precise regulation of loading rate (0.001mm/min to 500mm/min) and load holding (error ≤ ±0.5%);

Supports multi-mode control (load control, displacement control, strain control) and seamless switching between modes to meet diverse test requirements (e.g., creep test requires stable strain control, while tensile test needs load/displacement control).


1), Conform with stipulation of test standard ISO 6394 steel for prestressing of concrete – strand. And ASTM E328 steel stress relaxation test method.
2), Test load, displacement two control channel, and corresponding load, stress, displacement etc., control mode, this mode can change freely. PID control parameter can be adjusted real time.
3), Automatic collect, analysis, display test data, automatic measure the character point of test sample.
4), Automatic draw the relaxation force-time curve and adjust coordinates, always display in-time or complete curve. Automatic generate the force-displacement, force-time, displacement-time etc., test curve, automatic edit test report.
5), During relaxation test process, can control the constant displacement, to keep original strain or gauge keep no change.
6), Test time can more than 1000 hours, also can reckon the test data, use 100 hour to calculate the stress relaxation character of 1000 hours.
7), Steel strand relaxation testing machine with automatic zeroing and calibration function.
8), With overload, over current, displacement limitation etc., protection.
9), except to test the steel strand wire, also can use for the steel rod, rebar relaxation test.

ISO 15630-1, Steel for the reinforcement and prestressing of concrete -- Test methods -- Part 1: Reinforcing bars, wire rod and wire

ISO 6934-4, Steel for the prestressing of concrete -- Part 4: Strand

ASTM A370, Standard Test Methods and Definitions for Mechanical Testing of Steel Products

ASTM A416 / A416M, Standard Specification for Low-Relaxation, Seven-Wire Steel Strand for Prestressed Concrete.

ASTM E328 - 13 Standard Test Methods for Stress Relaxation Tests for Materials and Structures

Main technical specification

ModelLW-300R/500R
Max. load300KN/500KN
Measuring force range2%~100%
Accuracy of load±1% of indicated value
Test load measuring resolution1/200000
Tensile stroke0~200
Tensile test distance2000~2200
Displacement measuring accuracy≤±0.5%FS
Displacement resolution0.001mm
Grip moving speed0~20 (mm/min)
Steel strand clamping rangeφ12.7-φ15.2mm
Test time>1000
Temperature sensor accuracy±0.3℃
Power2Kw
Dimentions2100×800×1100mm


Main accessories (Standard delivery with machine)

High Stiffness Frame1 set
Controlled box (Oil cabinet)1 set
Oil Pressure sensor1 set
Hydraulic power system1 set
Photoelectric encoder for displacement1 set
Tool kit (screwdriver, spanner etc.,)1   set
Professional testing software (English version)1   set
Computer (HP or LENOVO computer, 19-inch LCD monitor, English Win10 system)1   set
Printer (HP A4 color inkjet printer)1   set
Documents (Manual, packing list, certificate)


Standard

EN 10319-1 Metal Tensile stress relaxation testing

EN 10319-1 specifies the test method for determining stress relaxation of metallic test pieces under nominally constant tensile strain and constant temperature. Steel strand tensile stress relaxation testing machine mainly used to check the prestressing steel material relaxation performance.

ASTM E328 Stress Relaxation Test for materials and structures

ASTM E328 test method are testing for the stress relaxation of plastics has been withdrawn from this standard, and the responsibility has been transferred to Practice ASTM D2991. These test methods cover the determination of the time dependence of stress (stress relaxation) in materials and structures under conditions of approximately constant constraint, constant test environment, and negligible vibration. In the procedures, the material or structure is initially constrained by externally applied forces, and the change in the external force necessary to maintain this constraint is determined as a function of time.

ASTM A1061, A416 Multi-Wire Steel Prestressing Strand Tensile Elongation Test

ASTM A1061 tensile test for breaking elongation stress relaxation on steel wire deals with the standard types and grade requirements of seven-wire, uncoated steel strands for use in the construction of pre-tensioned and post-tensioned pre-stressed concrete. 

The two types of strand specified by the ASTM A1061 specification are low-relaxation and stress-relieved (normal relaxation). The base metal shall be made of carbon steel and shall undergo stranding and continuous thermal and mechanical treatment. Final product requirements of ASTM A1061 shall be furnished on reels or in reelless packs for packaging and marked with two strong tags for identification. The requirements specified in ASTM A1061 shall also be applicable for pre-stressed ground anchor construction.

ISO 6934-4 Steel Strand Mechanical Test for the prestressing of concrete

ISO 6934-4 specifies mandatory requirements for stress-relieved steel strands used in prestressed concrete structures, test include Tensile / Strength & Ductility, Reverse Bend, Bend, Relaxation, Fatigue. It covers 10 grades of steel strands composed of 2, 3, 7 or 19 individual steel wires, including ordinary strands and compacted strands.


ISO 6934-3 Mechanical Test for Quenched and Tempered Steel Wire

ISO 6934-3 specifically targets quenched and tempered high-tensile steel wires used in prestressed concrete structures, test include Tensile / Strength & Ductility, Reverse Bend, Bend, Relaxation, Fatigue. The wire covered is round, available in plain, ribbed, grooved or indented surfaces, and delivered in coils.


ISO 15630-3 Testing of Prestressing Steel Strands Relaxation, Fatigue, Tensile testing

ISO 15630-3 specifies uniform, repeatable test methods for prestressing steel products: bars, wires, and strands used in prestressed concrete structures. Mainly include tensile test, bend test, reverse bending test, wrapping test, Axial force fatigue test etc., 

ISO 15630-2 Shear test machine and fixture for Welded steel fabric and lattice girders Steel

ISO 15630-2 Shear test machine and fixture for Welded steel fabric and lattice girders Steel are determined in tensile tests, flexure, node shear tests, high cycle fatigue tests. 


Node shear test The welded joints (nodes) of reinforcing welded fabric and lattice girders are tested for shearing. This involves removing specimens from welded fabrics and lattice girders and placing them in special close-fitting specimen grips. Specimen grips used for this type of test must be accurately matched to the diameter and position of the ribbed wires, so that they do not influence the shearing forces.

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