Testing and analysis of various elements of automotive materials

Inspection analysis of various elements of automobile materials

1. Overview

With the rapid development of performance and processing technology of non-metallic materials, non-metallic materials are being used at an unprecedented speed in automobiles. The average amount of non-metallic materials used in each car has increased from 68.4 kilograms in 1981 to 150-180 kilograms today. With the increasing application scope of non-metallic materials in the automotive field, requirements have also been put forward for the detection of corresponding properties of these materials, such as the impact of volatilization of toxic and harmful substances present in interior materials automobile on man. bodywork and the impact of volatile substances from interior materials on windshields. The impact of condensation on driver driving safety, tank breathabilitys of plastic fuel, the barrier properties of inner tubes and airbags, the impact of breathability and moisture permeability. human on passenger comfort, etc. For these questions, corresponding test methods, test standards and test instruments have also been introduced and continuously improved. Below is the technical department of Standard Group (Hong Kong) Co., Ltd. will briefly introduce the relevant test projects.

2. Detection of the impact of volatile substances of automotive interior materials on windshields

Automotive interior decoration materials, such as engineering plastics, textiles, leather, non-woven fabrics , etc., and the various adhesives used to install them materials. Under the action of high temperatures, their volatile components evaporate and formcondensation on car windows or windshields, causing poor visibility for the driver and seriously affecting driving safety. At present, testing in this field has been carried out abroad, and the relevant testing standards are DIN 75201, ISO 6452, SAE J1756, etc. Some domestic automobile and interior parts manufacturers have also conducted tests to improve product quality or expand overseas markets. Particular attention was paid to relevant tests.

There are two test methods for detecting fogging of interior parts: the gloss test method and the weight test method. The first measures the atomization characteristics of the test sample through the change of gloss of the glass plate before and after atomization; the latter measures the quality of the atomized condensate through the evolution of the mass of the fealuminum foil before and after atomization. In addition, the \"nebulization value\" or \"fog condensation quality\" obtained through the test can also quantitatively determine the amount of volatilization of toxic and harmful substances in the sample; By testing the fogging value of the xenon lamp in front of the car, it can also test how much the fogging of the headlights affects the lighting.

The atomization test equipment currently sold in the market Chinese companies include brands such as Standard Group, Panstandard and Qianshi.

3. Breathability performance test of automotive plastic fuel tanks

Compared with sheet steel fuel tanks, automotive plastic fuel tanks are safer, corrosion resistant and have a longer lifespan. Characteristics, random shape and low production cost. At present, the taow of use of plastic fuel tanks in Chinese cars reaches 86%.

Plastic fuel Although fuel tanks have many advantages over steel plate fuel tanks, their biggest disadvantage is the poor barrier properties of the material, which will cause penetrating volatilization fuel. Its barrier properties must be tested to select the ideal material. The traditional testing method is: after injecting a certain amount of gasoline into the fuel tank, sealing it, weighing the fuel tank to obtain its M1 mass, letting it sit for a sufficient time (usually more than 100 days ), weigh it repeat to get its mass M2, and calculate △M= M1-M2, △M is the volatile amount of fuel. This method requires a long test time and requires high-precision weighing tools, which is difficult toimplement.

ASTM D3985 gives another test method. Cut plastic sheets in the fuel tank, measure the oxygen permeability of the sheets, and compare the oxygen permeability of various plastic sheets to scientifically and quickly determine which plastic has the best barrier properties and is the most suitable for making fuel cans.

In ASTM F1307, the test method for the entire container is given, thus performing the leak detection test of the entire fuel tank.

4. Air and Moisture Permeability Tests of Car Seat Materials

When drivers and passengers travel long distances in cars, they often have to sit on multiple or even multiple seats in the car. Ten hours, so the air permeability and moisture permeability of car seat materials are more demandingset stricter than elsewhere. Good seat cushions and chairs should be soft and elastic, and have good breathability and moisture permeability, so that the sweat of the driver and passengers can be discharged smoothly and people feel comfortable. easy.

The air permeability testing method is: take a sample of specified size and place it in the testing chamber, vent one side of the sample to form a certain pressure difference on both sides of the sample and measure under this pressure difference. Calculate air permeability by measuring the flow rate of gas passing through a given area of ​​the sample over a certain period of time; or maintain flow through the sample, measure the pressure difference on both sides of the sample and calculate the resistance to air flow. This test method follows GB/T10655-2003.

The method of detecting hum permeabilityidity is as follows: sandwich the sample between the dry and humid chambers at a constant temperature. The sensor located in the newest chamber analyzes changes in humidity in the chamber and tracks the change from the preset lower limit value to the upper limit value. The time required, through multiple continuous measurements and system analysis, to obtain the moisture permeability and moisture permeability coefficient of the sample. This test method follows ASTM E398.

5. Gas Barrier Testing of Automotive Inner Tubes and Airbags

Materials used to make automotive inner tubes and airbags require good barrier properties. The first ensures the long-term performance of the car. Time passes without inflating, and the latter ensures that at the time of an accidental collision, it can quickly inflate and ensure certainty.groin pressure.

The traditional test method is to inflate the finished inner tube or airbag to a certain pressure, record the pressure gauge reading at that time, and after leaving it for a certain time, observing the pressure drop of the pressure gauge value to obtain its barrier performance. This type of detection method usually takes a long time to get the result (sometimes more than a year) and is difficult to implement. Jinan Languang\'s electromechanical technology can now be used. The gas permeability VAC-V1 produced by our company takes a sample of the material to be tested and fixes it on the instrument to maintain a constant pressure difference on both sides of the sample. It measures the change in pressure over time after the gas enters the sample. Thus, the barrier properties of the material can be obtained. The test in this area can be carried out within 24 hourss on the instrument, which greatly improves work efficiency.

6. Detection of other non-metallic materials in automobiles

Many non-metallic materials are used in automobiles, and the same material has different properties when used in different parts. Requirements, it is necessary to carry out detection of various elements. Such as tensile strength, tear strength, hardness, bending strength, color, coefficient of friction, etc.

In addition, when using automobiles, a large number of various adhesives are used. The performance of adhesives has a vital impact on the quality of the entire vehicle, so attention should be paid to this type of non-toxic adhesives. Metallic materials are subjected to performance tests such as shear, tension and pullout.

7. Conclusion

Non-metallic materials are lightweight andcan lighten automobiles to achieve energy-saving effects. In particular, the good processing technology of these materials gives automotive production a greater degree of freedom in the design and modeling of parts. As non-metallic materials are increasingly used in automobiles, materials testing will provide more powerful support for safety and optimal use of materials.

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