The application of dry-type on-board traction transformers (D-OBTTs) aims to achieve lightweight electric multiple units (EMUs) and support the approach for carbon neutrality. However

the production of large capacity D-OBTTs are limited due to the defects in insulation materials under the impact of short-circuit electromagnetic force. This paper is dedicated to enhancing the mechanical performance of the high-capacity D-OBTT under the influence of short-circuit electromagnetic force. It establishes and validates an electromagnetic force coupling model

while also analysing how the traditional structure leads to defects in the insulation material. To satisfy the requirements of safe and stable operation during the service life of the large capacity D-OBTT and minimise the weight

this paper proposes a comprehensive improvement of the mechanical performance under short-circuit electromagnetic force through material modification and structural optimisation. The improvement effect is verified through experiments and simulations. After comprehensive improvement

the tensile strength of the insulation material is 43% higher than the maximum principal stress on the contact surface of the insulation material

which meets the standard requirement and ensures long-term safe and stable operation of the D-OBTT during its service life.