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A lamellar structure characterized by two distinct inner and outer surfaces, where the thickness parameter t remains substantially smaller than both the minimum curvature radius R exhibited by the middle surface and the overall planar dimensions of the component, represents a foundati

At present, there are mainly the following categories on the market, plastic shell, aluminum shell, sheet metal shell, stainless steel shell and so on. Thin shell refers to the shell with t/R less than 0.05.

The structural behavior of shells fundamentally differs from planar structural elements through their distinctive internal force distribution mechanisms. Rather than relying predominantly on bending stresses that vary nonlinearly across the thickness dimension, as occurs in traditional plate structures, shells primarily resist externally applied loads through membrane stresses that distribute relatively uniformly throughout their thickness.

Shell theory constitutes a specialized domain within applied elasticity that extends beyond the foundational assumptions of classical elasticity theory by introducing supplementary hypotheses tailored to the unique structural characteristics of shell elements. This theoretical framework encompasses two primary subdivisions: thin shell theory and medium thick shell theory, each serving distinct engineering applications depending on geometric proportions and loading conditions. Thin shell theory represents the classical approach to analyzing shell structures and rests upon the adoption of the direct normal hypothesis, a set of three interconnected assumptions that fundamentally shape how engineers model shell behavior under various stress states. The first assumption establishes that the positive strain occurring in the direction perpendicular to the midplane remains negligibly small in magnitude and therefore can be disregarded in analytical calculations without introducing significant error.