Static Safety Design: Basis and Engineering Practice of Upper Limit of Stress of Disc Spring σⅡ and σⅢ

In the static load design of disc springs, controlling stress levels at critical points is fundamental to ensuring long-term safety and reliability. Notably, σⅡ (inner diameter lower edge stress) and σⅢ (outer diameter lower edge stress) are fatigue-sensitive parameters that require careful management even under static loads. Jiangsu Sunzo Spring will analyze the stress upper limit considerations under static loads by integrating international standards with engineering practices.

1、International Standard for Safety Design Criteria

According to ISO and other international general design criteria, for disc springs subjected to static loads, a basic safety requirement is that the calculated stress at critical points should be less than the material's tensile strength under 75% compression (0.75h₀).

Consider the commonly used spring steel (with a tensile strength Rm typically around 1600MPa) as an example:

Design logic: To ensure safety, a margin of working stress is required. The standard implicitly requires that under the theoretical extreme condition of flattening (100% compression), the calculated stress should also be less than the tensile strength.

Numerical relationship: When the stress approaches Rm (e.g., 1600MPa) at 75% compression, the flattening stress should be less than approximately 1600MPa / 0.75 ≈ 2133MPa based on linear proportion. This provides a macroscopic, safety-oriented reference for material selection and stress calculation.

2、Safety Margin and Design Reference of Standard Product

In fact, the design of serialized disc spring products compliant with GB/T 1972 or ISO standards has fully considered these criteria, with a substantial safety margin. Engineers typically do not need to conduct this verification separately when selecting standard products.

This condition must be considered for non-standard custom designs. A reference example is the DIN 6796 standard for elastic washers.

In the design, the σOM stress in the flattened state is controlled at approximately 1800MPa.

Accordingly, at 75% compression, the σⅡ stress is close to 1800MPa, which is within the safe range of tensile strength of typical spring steel.

This reflects the engineering practice of setting the working stress of the critical point below the tensile strength of the material and keeping a reasonable proportion in the static load design.

3、The Design Practice of Three-Group Elasticity: Safety is the Cornerstone of Reliability

In Jiangsu Sunzo Spring disc spring design and customization services, safety is the cornerstone of our technical evaluation.

Compliance with standards: We guarantee that our standard products fully comply with the inherent safety requirements of both national and international standards.

Customized Design: Our technical process for client-specific designs incorporates rigorous stress verification. We calculate stress at critical points (e.g., 0.75h₀) and evaluate stress levels under extreme conditions like compression, ensuring compliance with material safety limits. By applying design principles from established standards such as DIN6796, we deliver solutions that balance functionality with robust safety margins.

Material Science Applications: We recommend suitable materials (e.g., 50CrVA, 60Si2MnA) based on the designed stress levels to ensure material performance meets design specifications.

We firmly believe that excellence in design lies in striking the perfect balance between performance and safety. Through rigorous calculations, proven standards, and extensive engineering expertise, we deliver disc spring solutions that are both high-performance and secure, ensuring your equipment runs smoothly and reliably.