As a core component simulating the dynamics of surfing, the stress distribution of a land surfing bridge under dynamic loads directly affects its gliding stability and service life. Stress concentration typically occurs in areas of abrupt changes in component shape, material defects, or uneven loading. The risk of stress concentration is particularly pronounced in land surfing bridges under the combined effects of dynamic steering, center of gravity shifts, and ground impacts. Reducing this risk through structural improvements requires a comprehensive approach encompassing four dimensions: material selection, geometric optimization, connection design, and dynamic balancing.
Material selection is fundamental to reducing stress concentration. Land surfing bridges must withstand high-frequency dynamic loads. Traditional metallic materials are prone to cracking due to fatigue, while high-toughness composite materials (such as carbon fiber reinforced polymers) can delay crack propagation by uniformly dispersing stress. For example, a bridge structure using a hybrid of carbon fiber and glass fiber ensures strength while optimizing stress flow paths through the anisotropic properties of the fibers, reducing localized stress peaks. Furthermore, surface treatment techniques (such as shot peening) can introduce a residual compressive stress layer, further offsetting tensile stress under dynamic loads and reducing the probability of crack initiation.
Geometric optimization is a direct means of reducing stress concentration. The connection between the swivel arm and the bridge body, as well as the mounting holes for bridge studs, are prone to stress concentration due to abrupt changes in cross-section. Through fluid dynamics simulation or finite element analysis, right-angle transitions can be replaced with rounded or elliptical corners to ensure a smooth stress flow. For example, designing the edges of bridge stud holes as gradually curved surfaces instead of traditional flat surfaces can significantly reduce the stress concentration factor around the holes. For the welded joints between the swivel arm and the bridge body, using laser welding instead of traditional arc welding can reduce the heat-affected zone and avoid stress concentration caused by irregular weld shapes.
Connection design is a crucial factor affecting stress distribution. Bridge studs, spring nuts, and other connecting components in land surfing bridges are prone to fretting wear under dynamic loads, leading to increased local stress. Optimizing the connection structure can reduce stress concentration sources. For example, using a self-locking bridge stud design, the special angle of the thread allows the nut to automatically lock under vibration, preventing stress redistribution due to loosening. For spring nuts, they can be designed as an integrated structure with the swivel arm, reducing assembly gaps and lowering impact stress under dynamic loads. Furthermore, adding elastic gaskets (such as silicone or polyurethane) to the connection points can absorb some stress through material deformation, further reducing the risk of stress concentration.
Dynamic balance design is a core strategy for dealing with complex loads. Land surfing bridges must simultaneously withstand vertical impacts, horizontal steering forces, and torques during gliding. Reinforcing a single direction may lead to stress concentration in other directions. Multi-axis optimization design can maintain stress balance in the bridge structure under different loads. For example, designing the main beam of the bridge as a variable cross-section structure increases the cross-sectional height in areas with high steering forces and reduces the thickness in areas dominated by vertical impacts, achieving a dynamic match between stress and stiffness. Additionally, adding flexible bushings at the connection between the bridge structure and the deck can isolate some vibrations through material deformation, reducing the transmission of dynamic loads to the bridge structure.
Integrated damping systems are a supplementary means of reducing stress concentration. When land surfing bridges glide on rough surfaces, ground impacts are transmitted to the bridge structure through the wheels, causing high-frequency stress fluctuations. By adding damping modules (such as hydraulic or spring dampers) between the bridge structure and the axles, some impact energy can be absorbed, reducing the peak value of dynamic loads. For example, a dual-stage damping design is employed. The first stage uses springs to absorb large displacement impacts, while the second stage uses hydraulic dampers to attenuate high-frequency vibrations, resulting in a smoother stress transmission to the bridge structure.
Improved manufacturing processes are the last line of defense for ensuring structural precision. Machining errors in land surfing bridges (such as bridge body bending and hole misalignment) directly lead to stress concentration. By introducing CNC machining centers or 3D printing technology, the manufacturing precision of each bridge component can be improved, reducing assembly stress. For example, using a five-axis machining center to perform integral milling of the rotating arm avoids assembly errors after separate machining, ensuring the continuity of the stress flow path. Furthermore, polishing the bridge surface reduces defects such as surface microcracks, lowering the risk of stress concentration.
Reducing the risk of stress concentration under dynamic loads in land surfing bridges requires a comprehensive approach across the entire process, including design, materials, connections, damping, and manufacturing. Through the application of composite materials, geometric optimization, connection reinforcement, dynamic balance design, damping system integration, and improved manufacturing precision, the degree of stress concentration can be systematically reduced, extending the bridge's service life while improving sliding stability and comfort. This process not only relies on theoretical analysis, but also requires verification of the improvement effect through actual gliding tests, forming a closed-loop iteration of design-testing-optimization.
