OEM Bending Testing Machine Factory

What is the working principle of the bending testing machine?

In the modern industrial and scientific research system, the testing and analysis of the mechanical properties of materials are of vital importance, especially in the aspects of engineering structure safety and product durability evaluation. As a basic and widely used test method, the bending test plays a key role. As the core equipment for realizing this test process, the working principle and performance level of the bending testing machine are directly related to the accuracy of the test data and the reliability of engineering applications.
What is the bending test? Why is it important?
The bending test is an experimental method used to evaluate the mechanical properties of materials under bending load conditions, especially for evaluating the flexural strength (Flexural Strength), flexural modulus (Flexural Modulus) and its failure characteristics of materials. Compared with tensile or compression tests, bending tests can more realistically simulate the complex stress environment that structural components may encounter under actual working conditions.
For example, in the fields of plastic sheets, composite beams, metal pipes, etc., bending performance often determines their fracture resistance, ductility and service life.
Analysis of the working principle of the bending testing machine
Bending testing machines are usually based on the principle of levers and electronic force control systems. By precisely controlling the loading speed and loading position, they simulate the deformation process of materials under concentrated or distributed bending moments at a certain support spacing. The bending testing machines provided by Yiyu Instrument widely support three-point bending tests and four-point bending tests. The following introduces their basic principles:
1. Principle of three-point bending test
This method uses two support points and one loading point (loading head), and the force application point is located at the center of the support spacing. When the loading head gradually applies force downward, the maximum stress is generated in the middle of the specimen. The equipment collects the downward pressure (N) and deflection (mm) data and generates force-displacement or stress-strain curves for analysis.
Three-point bending is suitable for strength testing of most materials. It has a simple structure and high efficiency. It is the most commonly used bending test method in industry and teaching.
2. Principle of four-point bending test
In this mode, two loading points are equidistantly applied to the middle section of the specimen and supported by the support points at both ends. Compared with three-point bending, four-point testing can form a pure bending moment area in the middle of the specimen, which is more suitable for analyzing the performance of materials under stable stress conditions, especially for the evaluation of interlaminar shear strength of composite materials.
Control system and data acquisition technology
Yiyu instruments use a closed-loop control system that combines high-performance servo motors with precision load sensors, and cooperate with high-frequency data acquisition units (up to 200Hz or more), which can realize full automatic control of the test process, real-time data monitoring and automatic curve generation, ensuring the repeatability and stability of the test results.
We are also equipped with self-developed intelligent control software, which supports multi-language interfaces, can export test reports in real time, and widely supports GB/T, ISO, ASTM and other international standards to meet the professional testing needs of different customers.

How to ensure the consistency and repeatability of bending testing machines in repeated tests

Why are "consistency" and "repeatability" so important?
During the material testing process, the deviation of any parameter may lead to the misjudgment of the final conclusion, especially in the development of new materials, batch product quality control or standard comparison testing, the consistency of test data (whether multiple tests of the same equipment are close) and repeatability (whether multiple equipment and different personnel test to get the same result) are particularly critical.
Only with high consistency can "equipment error" be eliminated; only with strong repeatability can "data credibility" be guaranteed. Therefore, the structural stability, control accuracy, sensor system and standardization of the operating process of the testing machine itself will directly affect these two core performances.
Five technical means for Yiyu bending testing machine to ensure test consistency
1. High-precision force and displacement sensing system
Yiyu bending testing machine is equipped with internationally advanced strain load sensors with an accuracy level of more than 0.5, which effectively reduces data offset caused by force fluctuations. At the same time, the displacement control part adopts a high-resolution encoder and a closed-loop feedback control system, which can accurately control the loading displacement, and the error is controlled within ±0.1%, providing a solid guarantee for test repeatability.
2. Automatic calibration and zero self-check mechanism
Each Yiyu testing machine undergoes multiple working condition simulation calibrations before leaving the factory, and has one-button zeroing and automatic calibration functions. The system can automatically detect the force value and displacement baseline offset before each test, thereby avoiding data inconsistency problems caused by sensor thermal drift or time aging.
3. Strict mechanical structure design and manufacturing precision control
Yiyu Company insists on independent control of the entire process of mechanical manufacturing, from processing accuracy (support spacing tolerance, loading head verticality, etc.) to surface treatment (corrosion resistance, friction coefficient stability), all implement high-standard quality management systems, and the coaxiality deviation of structural parts is controlled within ±0.02mm, which greatly improves the stability of equipment operation.
4. Intelligent loading control system
We use the independently developed intelligent closed-loop servo control system, which can automatically set the loading rate curve according to the material characteristics, realize precise loading and feedback control, and avoid test errors caused by manual intervention. At the same time, the system has automatic termination, early warning prompts and multi-point loading data fitting functions, making the test process smarter and more accurate.
5. Standardized operation procedures and multi-channel data analysis functions
In order to help users achieve consistency in test operations, Yiyu provides standardized operation procedure instructions and intelligent software operating systems. The software supports comparative analysis of multiple sets of repeated data, automatically calculates the average value and standard deviation, and can generate complete PDF test reports according to international standards, effectively assisting experimenters to quickly identify abnormal data.
Service guarantee system ensures continuous consistency
In addition to hardware performance, Yiyu Instrument has also built a complete system for after-sales service and continuous optimization support:
Regular calibration service: Provide users with annual inspection, calibration and data comparison services to ensure that the equipment remains in good condition for a long time;
Remote diagnosis system: Improve the response speed of problems through remote debugging, status monitoring and data verification on the software side;
Training service: Provide regular training for enterprises/laboratories, including practical courses such as operation standards, error identification, and data interpretation.

How to calibrate the size of the specimen before the bending test on the bending testing machine

Why is specimen size calibration so important?
When conducting a three-point or four-point bending test, the thickness, width, length, flatness and corner treatment of the material specimen will significantly affect the stress distribution generated in the test and the final bending strength calculation results. For example:
The calculation of bending stress depends on the cross-sectional size parameters, and a thickness error of 0.1 mm may cause the result to deviate by several percentage points;
The bending modulus involves a mathematical model between displacement and span. If the size error exists, it will cause distortion in the material rigidity assessment;
National and international standards (such as GB/T 9341, ISO 178, ASTM D790) have made clear provisions for the specimen size and deviation range. Inadequate calibration will make the test data unable to pass the certification review.
Therefore, standardized dimensional measurement and calibration of the specimen is not only a prerequisite for ensuring the effectiveness of the test, but also the basis for achieving cross-laboratory data consistency.
Standard process for specimen size calibration before bending test
1. Initial measurement
Yiyu recommends that users use a high-precision vernier caliper or electronic micrometer to measure the thickness (h) and width (b) of each specimen at multiple locations (at least three points), and take the average value as the final size to ensure the accuracy of data input.
Yiyu bending testing machine control software has a built-in "specimen size entry and automatic correction" module, which supports the direct input of average thickness and width into the calculation formula to automatically correct the test results.
2. Edge and surface treatment
According to the standard, the edges of the specimen should be smooth and free of burrs, and the bending surface should not have microcracks. Yiyu recommends the use of special edge grinding equipment or sandpaper for fine grinding to prevent stress concentration during loading and cause premature damage.
3. Flatness and warpage detection
Use a platform ruler to check whether the specimen is bent, warped or twisted. Excessive warping will cause uneven loading points and affect the distribution of bending moment. Perform leveling if necessary.
4. Confirmation of span and ratio relationship
Different standards have requirements for the ratio of support span to specimen thickness. For example, GB/T 9341 recommends that the span be 16 times the thickness, while ASTM D790 requires it to be set within a specific range. Yiyu bending testing machine has an adjustable support structure, and users can quickly adjust and lock the span to ensure consistency with the standard.
Yiyu Instrument product advantages: escort for dimensional calibration accuracy
Zhejiang Yiyu Instrument Equipment Co., Ltd. combines years of industry experience and continuously optimizes products and services for the key links of specimen dimension calibration, which is specifically reflected in:
High-precision loading structure design
Yiyu bending testing machine adopts a high-strength guide rail system to ensure that the position stability of the loading head and the support is less than ±0.05 mm, providing a consistent loading environment for the accurately calibrated specimens.
Intelligent software support
Yiyu control system supports automatic input of specimen dimensions before the test. The system automatically matches the test standard based on the input dimensions, and completes dynamic corrections of force, stress, modulus and other calculations, effectively avoiding result deviations caused by manual mis-input.
Exclusive size detection tool package
Yiyu is equipped with special sample measurement fixtures and calibration tools for customers, which can quickly complete the thickness and width measurement of batch samples, and has data import function to improve experimental efficiency.