Seat Belt and Airbag Testing
Seat belts and airbags
are among the most important passive safety systems in a vehicle—they save lives. Their proper functioning is a prerequisite for protecting vehicle occupants in the event of an accident. ZwickRoell offers customized testing machines and testing systems for standard-compliant and reliable testing of these safety-relevant components – from development to series production and quality control.
Seat belt testing to UN/ECE-R16
Seat belts must meet a number of strict requirements. Testing is precisely defined, for example, in UN/ECE Regulation No. 16 (UN/ECE-R16) and in the USA in the Federal Motor Vehicle Safety Standard (FMVSS) 209. They are central regulations for the approval of seat belts and restraint systems in vehicles and contain a large number of tests, all of which are aimed at the reliability, durability and safety of seat belts - both at the individual component level (belt, buckle, tensioner) and at the overall seat belt system in the vehicle.
In addition to various preconditions for the belt (placement, humidity, temperature, light, drive, etc.) tests must be performed on a testing machine according to very strict specifications.
ZwickRoell testing machines can be used for a wide range of tests.
Tensile Test on Belts to EN ISO 1492
Seat belt manufacturers and original equipment manufacturers use ZwickRoell testing systems to determine the strength of the seat belts they produce (with and without buckle). The tensile test requires specialroller grips and an impact-resistant safety housing.
In addition to the tensile test, the release force of the belt buckle (unloaded and under tensile loading) is determined. In this test, the specimen is rolled in the roller grip and is held in place by itself; therefore, it is also recommended for specimens sensitive to clamping. Via the rolling of the rollers the specimen material is clamped independently due to the frictional contact.
Alternatively, capstan grips are also used with straps and belts. Specimens are clamped quickly and easily. These grips are also used for materials that are thin and sensitive to clamping forces and to prevent jaw breaks or to prevent specimen slipping during tensile tests. The force reduction curve reduces the tensile strength before end clamping. The specimen is held securely preventing jaw breaks,
An optical travel measuring system must be used for strain measurement, because a high degree of energy is released at break and the crosshead travel reference value for the strain cannot be precisely defined. Our videoXtens extensometer uses the structure of the belts and sets virtual gauge marks via software.
Video extensometers
Roller grips
Capstan grip
Tensile Test on Belt Connectors to DIN EN 1492
Belt connectors in the form of loops, knots, or clips are tested for their safety-related properties.
In the example shown, the maximum force that affects the stitching, the safety clip, or the seat belt is determined.
For this purpose, the conveyor belt is rolled up and held in place with the aid of a roller grip, and on the opposite side the bracket is clamped in a pneumatic grip. A force-travel diagram is recorded via the crosshead. No additional extensometer is required.
Airbag testing
Another important piece of safety equipment is airbags, which are now installed in many positions in the passenger area.
In addition to standardized standard tests such as tensile and tear growth tests on airbag fabrics, seams, and adhesives, ZwickRoell also offers tests on connectors, sensors, switching elements and predetermined breaking points of trims.
Tensile strength of airbag fabric
Tensile strength is a key mechanical parameter for assessing airbag fabric. Two internationally recognized methods are used to determine it in accordance with standards: the strip tensile test and the grab test. While the strip tensile test involves uniformly loading a precisely cut specimen strip, the grab test method simulates the behavior of the fabric in the composite by partially clamping it. Both methods provide different but complementary information on the load-bearing capacity and usability of these technical textiles.
In addition to the tensile and grab tensile tests, airbag textiles are also tested for seams and adhesive bonds in tensile tests. This involves comparing unsewn or unbonded fabrics with sewn or bonded specimens in accordance with ISO 13935-1/-2 or ISO 13936-1/-2. These standards specify methods for determining the maximum tensile force of seams where the load is applied perpendicular to the seam.
Strip tensile test on airbag fabric according to ASTM D5035, ISO 13934-1, and ISO 1421
The strip tensile test on airbag fabric is described in the international standards ISO 1421 as method 1 as well as in ISO 13934-1 and ASTM D5035 and determines the maximum tensile force and the breaking behavior of a single, uniformly loaded textile strip. Therefore, it is particularly suitable for assessing material strength, quality control in incoming goods and production, and for comparing different material batches.
Due to their special coating and finishing, airbag fabrics are characterized by a smooth, slippery surface and generally have very low strain. Suitable jaw inserts and pneumatic grips with a high gripping force are therefore important in order to prevent the specimen, which is usually sensitive to clamping, from slipping and to achieve a standard-compliant break.
Our ProLine and AllroundLine in the force range between 10 kN and 20 kN paired with our single actuator pneumatic grips (10 kN or 30 kN) are the best choice for standard-compliant testing in order to be able to perform all standard tests on airbag textiles.
Grab tensile test to ASTM D3034, ISO 13934-2, ISO 1421
In addition to the strip tensile test, airbag fabrics are also tested using the grab test method, which is described in detail as method 2 in the international standards ASTM D5034, and ISO 1421.
In the grab tensile test, the specimen is only clamped in the center region, which specifically tests the bonding behavior of the fabric. Unlike the classic strip tensile test, in which loading is uniform, the grab test simulates a controlled elongation within the fabric in order to determine the maximum force in the bond realistically and to be able to evaluate the stability of the fabric in use.
The same test equipment can be used in the grab test as in the strip tensile test.
Learn more about the grab test
Tear growth tests to ISO 13937-2 and ASTM D2261
Tear growth tests on airbag fabrics are performed in accordance with ISO 13937-2 or ASTM D2261 using so-called trouser-shaped specimens. A rectangular specimen is incised at a narrow edge to create two legs, which are pulled apart parallel to the incision in a tensile testing machine. The tear growth force applied is determined via the force curve. The test is used to determine the force required to continue the crack along the incision.
For reliable results, we recommend using ZwickRoell universal testing machines from the ProLine or AllroundLine series, equipped with pneumatic grips to prevent the specimen from slipping.
Testing of airbag connectors
Airbags are among the most important safety components in vehicles and the requirements for flawless deployment are correspondingly high. To ensure the secure connection of airbag connectors, Delphi Connection Systems Deutschland GmbH conducts tests on the mechanical and electrical properties already during the development phase.
Since the sound generated during engagement (audible feedback) alone is not sufficient, the company relies on a combined mechanical, electrical, and optical test. An AllroundLine testing machine from ZwickRoell is used, which is characterized by its flexible expandability. An integrated PCIe measurement card in the testControl electronics measures the current synchronously during insertion and visualizes the electrical contact progression.
At the same time, the engagement process is monitored optically from two perspectives. To do this, ZwickRoell uses the specially developed multi-capture function, which enables synchronized video recordings – even with up to four cameras if required. testControl II processes all incoming signals at high speed and provides maximum modularity for complex test scenarios.
