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Tailor made Bi-axial Tensile Tooling for ESA ESTEC!

Space structures such as solar panels and rocket motor casings, are made of carbon fibre reinforced composites (CFRP). To guarantee that these materials work well in space, they must be tested thoroughly. CFRP materials are characterized by properties that change along different directions, this makes it essential to conduct bi-axial tensile material tests.

Bi-axial  tensile tests

ESA ESTEC has an Instron 8802 servo-hydraulic Universal testing system available for material testing. This system can conduct uni-axial tensile and compression tests upto 250kN. ESA ESTEC is looking for a Bi-axial tensile tooling that fits into this Instron system.

ENDUTEQ has taken up this challenge to develop and build a compact and innovative solution to perform bi-axial tensile tests. Based on the following principles:

  • Maximum biaxial tensile force: 100kN in each direction; max stroke 100mm.
  • Possibility to test different material thicknesses from 0mm upto 20mm.
  • No bending loads due to bi-axial movement are allowed on the specimen.
  • Clamping mechanism must create an evenly clamped specimen.
  • Tooling must be easily loaded into the Instron system, without any extra tools.

Technical challenges

Carbon fibre reinforced composite is strong and stiff, vulnerable to point loads. To prevent damage on the specimen, the clamping force must be evenly distributed over the complete clamping area. And no bending loads are allowed on the specimen.

In close cooperation with engineers from ESA ESTEC, we have developed a tailor made solution; based on a previously developed concept.

Bi-axial Tensile Tooling

The Tooling consists of 4 clamping units each mounted on a linear guide. The clamping units are coupled to a central compression block with hinged levers. All clamping units pull with the same force when the Universal Testing system applies a load on the compression block. In this way the specimen is pulled simultaneously on 4 sides. Important is to acknowledge that the tensile force on the specimen increases when the angle of the lever decreases. This is compensated in the testing program.


ESA ESTEC has no lifting facilities available in their test lab. To be able to load and unload the Bia-axial tensile tool (appr 350kg) we have developed a tailor made (un)loading trolley. This trolley can also be used to temporarily store the Biaxial tool. See video below:

 These kind of smart solutions are characteristic for our company. Are you looking for smart tailor made testing solutions? Please contact one of our specialists, we are happy to support you !