The tear resistance of a PVC soft-rubber keychain is a core indicator of its durability. Structural design requires comprehensive optimization across multiple dimensions, including material distribution, geometry, stress distribution, and connection processes, to enhance the product's resistance to damage during actual use.
Material thickness gradient design is a fundamental strategy for enhancing tear resistance. By increasing the thickness locally at the edges or in areas of concentrated stress on a PVC soft-rubber keychain, a "thick-to-thin" transition structure can be created. For example, thickening around the keychain's hanging hole ensures overall lightweighting while increasing the tear resistance threshold at critical locations. This design utilizes material thickness differences to direct stress transfer to high-strength areas, preventing premature cracking at weak points. Furthermore, the thickness gradient must transition smoothly to prevent the initiation of new crack sources caused by sudden stress changes.
The layout of internal reinforcement ribs significantly enhances tear resistance. Embedding hidden reinforcement ribs within the flat or curved surface of a PVC soft-rubber keychain creates a three-dimensional support network. For example, employing a cross-shaped or radial rib design effectively disperses localized stress under external forces. The cross-sectional shape of the reinforcing ribs should be optimized to an arc or trapezoidal shape to avoid stress concentration caused by right-angle structures. Furthermore, the connection between the ribs and the main structure should feature a rounded transition to further reduce the risk of tearing.
Curved transition design is a key method for reducing stress concentration. Right-angled edges or sharp corners on PVC soft-rubber keychains are prone to crack initiation. Replacing right angles with large-radius rounded corners can significantly reduce stress concentration. For example, a gradually curved design at the connection between the keychain body and the hanging ring ensures more uniform stress distribution when external forces are applied. Furthermore, the curved transition improves the product's feel and enhances the user experience.
Layered composite structures enhance tear resistance through complementary material properties. PVC soft-rubber keychains produced using a two-color co-extrusion process can use a high-hardness PVC outer layer and a flexible PVC or TPU elastomer inner layer. This "hard-soft" composite structure ensures surface wear resistance while absorbing impact energy through deformation of the inner elastomer. If microcracks appear in the outer layer, the inner layer prevents crack propagation, forming a "crack-blocking layer."
The optimized design of the hanging hole structure directly impacts the tensile strength of the keychain. Traditional circular hanging holes are prone to shear stress at the edges, leading to tear propagation. By changing the hanging hole to an elliptical or racetrack shape and increasing the hole wall thickness, the stress in the tensile direction can be effectively dispersed. Furthermore, annular reinforcement ribs within the hanging hole can further improve local load-bearing capacity. Furthermore, a gradual transition should be used at the connection between the hanging hole and the keychain body to avoid stress concentration.
Texture design enhances tear resistance through physical toughening. Imprinting regular or irregular textures on the surface of a PVC soft-rubber keychain, such as diamond lattices, wavy patterns, or granular protrusions, increases the material's surface friction coefficient and deformation space. When subjected to external forces, the textured structure guides crack propagation along a specific path, creating a "crack deflection" effect. Texture also enhances product aesthetics and meets personalized needs.
Modular connection design reduces the risk of tearing through structural separation. For PVC soft-rubber keychains with complex shapes, a split design can be adopted, connecting the main body and decorative components through snap-fit or nested structures. This design concentrates stress on the connection rather than the material itself when external forces act. By optimizing the strength and toughness of the connection, it ensures that under extreme stress, only the connection fails, while the main body remains intact. The modular design also facilitates repair and replacement, extending the product's lifespan.
