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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. 


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

GB/T 10120 Metallic materials-tensile stress relaxation.

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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 10391, ASTM E328-2013, 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)


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Beijing United Test Co., Ltd.