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Description
The inner tracker (ITK) of the reference detector for Circular Electron Positron Collider (CEPC) imposes stringent requirements on mechanical support structures, including an ultra-low material budget, high stiffness, and long-term stability under radiation. This paper presents the full development of a 1000 mm long triangular-section carbon fiber reinforced polymer (CFRP) truss beam for the CEPC-ITK, covering structural design, finite element analysis (FEA), mold design and optimization, fabrication process development, and static mechanical testing. The truss beam consists of three longitudinal primary beams made from M40J high-modulus carbon fiber prepreg and helical secondary beams made of T700 carbon fiber tows. To improve node integrity, a continuous fiber winding process was developed replacing the segmented bonding approach. The total winding fiber length is approximately 7 m. The fabricated 1000 mm beams has a mass of ~15 g, corresponding to a linear density of ~15 g/m. Static mechanical tests show a deflection of 37.25 ± 0.96 μm under a 50 g concentrated load with fixed support, good agreement with FEA prediction(2.6% deviation). Under a uniformly distributed load of 80 g (simulating realistic sensor loading), the deformation is approximately 20 μm. The good agreement between FEA results and measurements under different boundary conditions validates the structure design and fabrication methodology. This study provides an experimental verification for the engineering design of lightweight support structures for the CEPC-ITK.
