Variation in applied forces between fasteners can be limited to ±10 percent by adjusting the constants of the flange such that
通过调节凸缘常量，可将紧固件之间所施加力的差值控制在 ±10 ％之内，这样
βD = 2,
where
其中
k = foundation modulus of the seal
k = 密封件的基础模量
E? = the modulus of elasticity of the flange
E? = 凸缘的弹性模量
I? = the moment of inertia of the flange and seal
I? = 凸缘和密封件的惯性矩
d = spacing between fasteners
d = 紧固件之间的间距
The modulus of elasticity (Ef) for steel is typically 3 x 107. The modulus for aluminum is typically 1 x 107, and for brass it is about 1.4 x 107.
钢的弹性模量 (Ef) 一般为 3 x 107。铝的弹性模量一般为 1 x 107，黄铜一般为 1.4 x 107。
The foundation modulus (k) of seals is typically 10,000 to 15,000 psi. The moment of inertia (lf) of rectangular sections, for example, may be obtained from the following expression 2:
密封件的基础模量一般为 10,000 至 15,000 psi。矩形的惯性矩 (lf) 可通过下面的表达式2 得到：
where
其中
b = the width of the flange in contact with the gasket (inches) and h = the thickness of the flange (inches).
b = 凸缘与垫片之间接触面的宽度（英寸）；h = 凸缘的厚度（英寸）。
Example
举例
Calculate the bolt spacings for flanges with a rectangular cross-section, such as shown in Figure 12, where
计算一个矩形截面凸缘上的螺栓间距，如图 12 所示，其中
h is the thickness of the flange.
h 是凸缘的厚度。
b is the width of the flange.
b 是凸缘的宽度。
d is the spacing between fasteners.
d 是紧固件之间的间距。
Figure 12. Bolt Spacings for Flanges
图 12. 凸缘上的螺栓间距
Assume the flange is to be made of aluminum.
假定该凸缘由铝制成。
To maintain a pressure distribution between bolts of less than ±10 percent, ?d must be equal to 2 (see Figure 13 and discussion).
要使螺栓之间的压力分布差小于 ±10 ％，?d 必须等于 2 （见图 13 和相关讨论）。
华译网上海翻译公司曾经翻译过大量有关紧固件间距资料文件，Beijing Chinese Subtitling Translation Service Agency has translated many technical documents about Fastener Spacing.
Figure 13. Array Factor vs. Spacing
图 13 排列系数 vs 间距
Assume an average foundation modulus (k) of 12,500 psi for the seal. If the actual modulus is known (stress divided by strain), substitute that value instead.
假定密封件的平均基础模量为 12,500 psi。如果知道实际模量（应力除以应变），则可使用实际值替代该值。
The bolt spacings for aluminum flanges for various thicknesses and widths have been calculated for the previous example and are shown in Figure 14.
我们对上例中各种厚度和宽度的铝凸缘计算了螺栓间距，结果如图 14 所示。
The previous example does not take into account the additional stiffness contributed by the box to which the flange is attached, so the results are somewhat conservative.
上例中未考虑凸缘安装箱体产生的额外刚度，因此，结果有一定的保守性。
Actual deflection vs. distance between fasteners may be computed from the following expression:
实际变形和紧固件之间距离的关系可通过下式计算得到：
References
参考资料
1. Galagan, Steven, Designing Flanges and Seals for Low EMI, Microwaves, December 1966.
2. Roark, R. J., Formulas for Stress and Strain, McGraw-Hill, 4th Ed., p. 74.
where p is the force applied by the fastener, and β and k are the constants of the flange as determined previously. N represents the number of bolts in the array.
其中 p 是紧固件施加的力，β 和 k 是前面确定的凸缘的常量。N 代表排列中的螺栓数目。
The array factor denoted by the summation sign adds the contribution of each fastener in the array. The array factor for various bolt spacings (βd) is shown in Figure 13. Although any value can be selected for βd, a practical compromise between deflection, bolt spacing and electrical performance is to select a bolt spacing which yields a value βd equal to 2.
累加符合所表示的阵列系数将各螺栓的贡献力加起来。各螺栓间距（βd）下的阵列系数如图13所示。虽然 βd 可选为任意值，但应综合考虑变形、螺栓间距和电气性能来选择的螺栓间距，得到的 βd 值为2。
Figure 14. Fastener Spacing
图 14. 紧固件间距
For βd = 2, the flange deflection fluctuates by ±10 percent. Minimum deflection occurs midway between fasteners and is 20 percent less than the deflection directly under the fasteners. The variation in deflection is approximately sinusoidal.
对于 βd = 2，凸缘变形在百分之±10间波动。紧固件之间中间位置的变形最小，比直接紧固件下方处的变形小百分之20。变形的变化近似为正弦曲线。
Table 5 lists a few recommendations for bolts and bolt spacings in various thin cross section aluminum flanges.
表5列出了各种薄截面铝凸缘螺栓和螺栓间距推荐值。
Bolt spacings for waveguide flanges are fixed by Military and EIA Standards. Waveguide flanges normally have bolts located in the middle of the long dimension of the flange because the flow of current is most intense at this point.
军方和EIA标准规定了波导凸缘的螺栓间距。波导凸缘通常有螺栓位于凸缘长尺寸中间，因为这点的电流强烈。
4. Common Fasteners
4. 普通紧固件
Many different types of fasteners are available, but bolts are the most widely used fastening devices. The approximate torque required to apply adequate force for mild steel bolts is shown in Table 5.
可以使用多种不同类型的紧固件，但螺栓是最广泛使用的紧固装置。低碳钢螺栓要使施加力合适，所需扭矩近似值如表5所示。
Table 5: Bolt/Spacing Recommendations
表5:螺栓/间距推荐值
SCREW SIZE
螺栓尺寸 Centerline to Centerline (in.)
中心线至中心线（英寸） Thickness
厚度
(in.) Max. Torque to Prevent Stripping for UNC-2A Thread
UNC-2A 螺纹防脱最大扭矩 |
