The bogie

as the force-bearing structure of rail transit vehicles

is critical to operational safety

with weld quality directly influencing structural integrity. To address limitations in existing inspection methods for bogie welds

this study systematically analyzed weld characteristics and conventional detection techniques

proposing phased array ultrasonic testing (PAUT) for defect detection: butt welds were inspected using PA probes in single-side double-side scanning mode

employing both primary and secondary transverse waves to cover the inspection zone; fillet welds adopted a dual-probe combined detection configuration

implementing sector scanning on the web side with an angled wedge generating shear waves

while electronic scanning was performed on the flange side using a 0° wedge. A multiphysics finite element model of the weld joint was established through COMSOL Multiphysics software to simulate acoustic beam propagation characteristics and defect reflection behaviors

thereby determining beam coverage areas and echo signal features. To validate technical feasibility

experimental tests were conducted on actual weld samples including butt welds and fillet welds containing natural defects (slag inclusion

internal flaws

etc.)

artificial defects

and frame structures.

Results

2

demonstrated that PAUT achieved 100% defect detection rate

with all defect signals exhibiting signal-to-noise ratios exceeding 12 dB. The method effectively distinguished defect signals from structural noise interference

showing significantly improved detection accuracy and reliability compared to conventional approaches. This research validates the technical advantages of phased array ultrasonic technology in complex weld inspections

providing an efficient and precise non-destructive testing solution for quality control of rail transit bogie welds

which holds substantial engineering application value for ensuring operational safety in rail transportation.