技術支持 Support
聯系方式 Contact

地址:懷來東花園鎮航天產業園緯二路2號

電話:137 0121 6722

傳真:010-60934713

郵件:hthjgy@163.com

在線QQ交談 在線QQ交談

搜索 Search
你的位置:首頁 > 技術支持

SQUIRM OR INSTABILITY

2016-5-7 21:59:04點擊:
All bellows have a critical pressure at which they become unstable. Instability can occur in either of two modes, column instability (or squirm), or in-plane deformation of the convolution side wall. Squirm affects the bellows as a whole, while in-plane deformation only affects one or more convolutes individually.
Column instability (or squirm), is the phenomena whereby the centerline of a straight bellows develops a sideways or lateral bow.
The critical pressure at which this instability occurs is a direct function of the diameter and spring rate, and an inverse function of the length. If the bellows is bent, or angulated, the centerline can begin to move away from the center of curvature.
 
In each case, the effective length of the bellows increases, lowering the material available to withstand the pressure, thereby increasing the hoop stresses. As the length increases, the tendency to squirm increases and the stresses become higher and higher until catastrophic failure occurs.


A simple way to visualize this phenomena is to remember that the bellows is a cylinder of given volume. Internal pressure tries to increase a vessel's volume. Since a bellows is flexible in the axial direction, it can increase its volume by increasing the length of its centerline. With the ends fixed, it does so by simulating the appearance of a buckling column.


We perform standard pressure tests on all our bellows to ensure the unit will not squirm in service. Tests are not mandatory by EJMA, but it is highly recommended to perform a pressure or hydrostatic test prior to service.
欧美亚洲综合另类色妞网|亚洲日韩精品无码AV海量|久久香蕉综合色一综合色88|2021国产三级在线观看