Design of attitude-adjustable chassis and dynamic stress analysis of key components for crawler combine harvester

To address the issues of leveling difficulties and poor stability of crawler combine harvesters in hilly and mountainous regions, this research analyzed the mechanical causes of overturning instability in crawler combine harvesters and designed an omnidirectional attitude adjustment chassis based on a five-bar mechanism. A 3D model was developed in SolidWorks, and coupled rigid-flexible simulations were performed using RecurDyn. Results showed that the chassis could achieve an overall lift, lateral adjustments and longitudinal adjustments (0-100 mm, -5.18° to 5.55° and -4.06° to 5.15° respectively), with maximum dynamic stress occurring on the left front and left rear rotational arms. A dynamic stress testing system was established to conduct response surface experiments. Field test results revealed that the primary factors affecting the maximum stress of the left front rotational arm were the grain tank loading mass, lateral adjustment angle, and longitudinal adjustment angle. For the left rear rotational arm, the order was the longitudinal adjustment angle, lateral adjustment angle, and grain tank loading mass. Validation tests showed that at a lateral adjustment angle of 3.61°, a longitudinal adjustment angle of 3.20°, and a grain tank load of 350 kg, the average maximum stresses were 483.19 MPa for the left front rotational arm and 188.95 MPa for the left rear rotational arm, with corresponding structural safety factors of 1.61 and 4.31, meeting strength requirements. This work provides methods for optimizing the design and reliability testing of agricultural machinery chassis with attitude adjustment functions in hilly terrains.