Test Benches: Ensuring Accuracy and Reliability of Product Testing

Let's say you're in the process of creating an engine test stand. Now, ask yourself: "Are you certain you've taken into account all the ins and outs of designing testing setups?" If your answer is "No," then dive into the following.

In every industry, new product development requires testing the final product before reaching the end consumer. Test benches enable making the testing process repeatable and predictable. Testing stands are complex systems designed to simulate real conditions and evaluate product characteristics. In this article, we will examine the peculiarities of designing stands, as well as the strategies we employ to ensure the accuracy and reliability of product testing.

Design Peculiarities of Test Benches

To ensure the accuracy and reliability of testing, several aspects need to be considered when designing a test bench. Below are the key points to focus on:

Emergency Shutdown Mechanism

A testing stand should include an emergency shutdown mechanism that activates upon exceeding the allowable load. In this case, the stand will be halted to prevent tire damage and operator injury.

Protective Barriers

For test benches designed to test electronic components for impact resistance, protective barriers should be installed to prevent shrapnel dispersion in the event of component failure.

Fuse Protection

In testing stands designed for testing equipment for seal integrity, fuses should be installed to prevent testing if the equipment is not properly sealed.

Regular Calibration of Measuring Instruments

Pressure and temperature gauges used in testing stands for pressure and temperature testing should be regularly calibrated to ensure measurement accuracy. This can be done by comparing gauge readings with those of calibrated instruments.

Modular Design Selection

Vibration Test Bench

A vibration test bench should be modular to facilitate easy upgrades for testing various types of products. For example, additional sensors can be added to measure vibration at different points of the product.

Fatigue Test Bench

A fatigue testing stand should be modular to allow easy adaptation for testing various types of loads.

Fault-Tolerant Mechanisms

Limit Switches

Limit switches should be installed in testing stands for material destruction testing to activate upon reaching critical loads. This helps prevent stand or tested product damage.

Laser Sensors

For equipment seal integrity testing stands, laser sensors or other leakage sensors should be installed to monitor leaks. This helps prevent equipment damage.

Environmental Conditions

Temperature and Humidity

A testing stand for thermal and humidity resistance testing should be located in a room with constant temperature and humidity to ensure accurate test results.

Detailed Documentation

Calibration Protocols

Calibration protocols are the basis for analyzing calibration results and taking appropriate corrective actions when necessary. They establish standard calibration methods for different types of instruments, calibration frequency according to manufacturer requirements or standards, document the calibration process, including the use of standard samples, measuring devices, and verification methods.

Operating Procedures

Establishing operating procedures for a testing stand is equally essential. This document describes the steps for installation, startup, and use of the stand, including necessary precautions, training operators on proper equipment handling and accident prevention, key parameters and indicators to monitor during stand operation, and instructions for equipment maintenance and care to ensure its integrity.

Designing for Operator Needs

Intuitive User Interface

The user interface of a testing stand should have readable fonts, contrasting colors, simple and understandable icons, and text prompts. To achieve a clear interface, clear icons, labels, and controls are implemented. Remember the principle of "The fewer controls (within reason), the more convenient." The user should also receive immediate feedback on the results of their actions. This can include displaying messages about successful operation, animations, or changes in the state of interface elements.

Staff Training

This point may seem obvious, but it is often overlooked. Personnel operating the testing stand should undergo proper training to ensure its safe and effective use.

These are just some examples that can be provided for each point. When developing a specific testing stand, it is necessary to consider the specific requirements and conditions in which it will be used.

Testing Stands Developed by EnCata

Thermal Manikin

The Thermal Manikin Complex is used for testing specialized protective clothing and firefighter gear. The material is tested for resistance to open flame and thermal flux. The testing complex consists of a specially designated room, a manikin, a mobile device for securing the manikin, a portable measuring rack, a gas rack for simulating the fire source, a thermal panel, and a measuring system.

To enhance safety, the "Thermal Manikin" testing complex is equipped with the following devices:

• limit switch indicating an open door;
• gas leakage detection system;
• stage-by-stage preparation and execution of testing. The program algorithm does not allow proceeding to the next stage without completing the previous one.
• automatic removal of the manikin from the work zone when critical values are reached;
• control of water consumption in the cooling system;
• two measuring racks are used to control the ambient temperature and thermal flux in the work area. Each rack contains thermoelectric converters with a measurement range from 0°C to 1000°C (1) and cooled heat flux sensors with a measurement range from 1 to 100 kW/m2 (2), three each.

To maintain the combustion process and remove combustion products generated during testing, the testing complex is equipped with a ventilation system. An exhaust hood is located above the work area. The ventilation system's performance is adjustable, depending on the type of test; the control program automatically sets the required flow rate, ensuring safe experiment conduct.

Thanks to the thermal manikin, new PPE (Personal Protective Equipment) for firefighter protection is developed and tested. The manikin is dressed in test clothing and exposed to gas installations and thermal panels. The PPE's resistance to open fire is tested in the gas installation area, while the thermal panels apply directed heat flux of 80 kW. The flame from the gas burners closely resembles that of indoor fires. We integrated a system of 32 sensors into the manikin and built an entire measurement system that displayed temperature indicators in different parts of it in real-time on the screen. Our electronics development expertise ensured seamless integration for accurate monitoring. The manikin has a water cooling system, allowing it to cool rapidly after testing. This enabled conducting dozens of tests per day.

Testing Complex for Pressure Sensors in Tires

A client approached us with a project aimed at implementing their own tire-saving technology for heavy machinery by monitoring tire pressure. Our team was tasked with developing a complex of stands for testing pressure sensors in tires.

The complex consists of the following devices:

• stand for testing pressure sensors;
• thermal cycling chamber for sensor testing.

Tire Pressure Sensor (TPMS) Testing Stand

The Tire Pressure Sensor Testing Stand (TPSTS) is a device that monitors the quality of the finished product. The stand tests tire pressure sensors for pressure measurement accuracy. The system consists of a testing chamber and a control unit.

Due to the high pressure in the system, our primary task was to ensure the chamber's tightness. For this purpose, we chose standard shut-off valves capable of withstanding pressures up to 12 bar. Such a solution already includes working with high pressure and provides greater reliability and predictability in behavior compared to a newly assembled system.

Inside the chamber, there is a compact radio antenna that receives data from the tire pressure sensor and transmits it to the stand's microcontroller. To allow for 10 tests to be conducted simultaneously and for the microcontroller to recognize which chamber the signal came from, we modified the signal processing unit so that the receiver was placed on the screen where the sensor is being tested. Additionally, the receiver will be isolated from the main device to prevent it from receiving signals from other sensors.

The principle of operation of the pressure testing chamber is as follows:

1. The operator places the sensor in the chamber cell.
2. The set pressure is applied to the cell.
3. The sensor receives data and transmits it to the stand's microcontroller.
4. The microcontroller compares the sensor data with the digital manometer readings on the pneumatic line.
5. If the data matches, the sensor is functioning correctly.
6. Then, the sensor's response to pressure release to 0 is checked. The sensor should quickly respond and notify the operator of the pressure drop.

Next, the sensor is placed in the thermal cycling chamber.

Thermal Cycling Chamber

The thermal cycling chamber simulates extreme weather conditions for a set period. This allows the operator to determine the sensor's ability to operate in extreme weather conditions. The chamber maintains temperatures from -70°C to +180°C. The chamber is controlled using software. Chamber settings and operating modes can be changed through the chamber interface or by connecting to a PC via a USB cable.

The thermal cycling chamber uses fuses to protect heaters, fans, and electronics. In case of a short circuit or overload, the fuse blows, cutting off power to the corresponding component.

Our team also provided emergency stop software, which allows the chamber to be manually shut down via the software interface.

Calibration protocol preparation was a mandatory step, including temperature, humidity, and pressure calibration.

Advantages of the testing complex:

• Wide measurement range: The complex allows pressure measurements in the range from 0 to 12 bar.
• Ease of use: The complex is easy to use and does not require special operator training.
• Universality: The complex can be used to test pressure sensors in tires of various types.

The testing complex can be used in various industries, including automotive, aerospace, and others.

In closing,

Testing stands play a critical role in manufacturing, ensuring the accuracy and reliability of product testing. The reliable design of stands is achieved through the implementation of mechanisms such as emergency shutdowns, protective barriers, fuses, regular calibration of measuring instruments, limit switches, laser sensors, etc. Control of environmental conditions, detailed documentation, and staff training all contribute to obtaining accurate test results. Operational safety is ensured by an intuitive user interface and qualified personnel.

Ultimately, testing stands are a valuable investment that improves product quality by reducing risks, shortening time to market, and enhancing the company's competitiveness. Examples of such stands at EnCata include the thermal manikin for evaluating firefighter protective clothing and the complex for testing pressure sensors in tires, equipped with necessary safety systems and capable of simulating real operating conditions.