**2.2 Yoke plate cutting angle concept**

A new design concept referred to as "Yoke plate cutting angle" is introduced as a design variable. This unique concept provides control over the stress distribution at the yoke plates interface by means of a resulting friction force generated at the surface-to-surface contact interface. The angled (non-horizontal) contact interface between the yoke plates and side yoke plates allows both plates to work in unison to carry the pressure load while still providing some accommodation for stress deflection by allowing slip plane movement between the plates. The yoke plates' cutting

#### **Figure 2.**

*(a) General component layout and materials used, (b) general dimensions and design parameters and (c) stress-probing locations.*

**25**

**Figure 3.**

*Sustainable and Efficient Hydroforming of Aerospace Composite Structures*

*Material properties of winding frame and yoke plates. (7075-T6 aluminum).*

Elastic modulus E 71.7 GPa Poisson Nu .33 Density Rho 2.81e−9 Yield point σ 503 MPa

angle dictates the magnitude of the frictional force occurring at the interface. Thus, special attention must be paid to this dimension. A precise yoke plate cutting angle definition will allow contact related stresses to be just below the material's yield, while helping reduce the stress of the composite winding. Coulomb dry friction is a good starting point to approximate the maximum cutting angle that generates

*(a) Boundary conditions and mesh, (b) applied loads and (c) contact definitions.*

*DOI: http://dx.doi.org/10.5772/intechopen.81505*

**Table 1.**

#### *Sustainable and Efficient Hydroforming of Aerospace Composite Structures DOI: http://dx.doi.org/10.5772/intechopen.81505*


**Table 1.**

*Environmental Impact of Aviation and Sustainable Solutions*

**2.1 Basic structural configuration and FEA design parameters**

exploration procedure, allowing for different evolving design configurations.

In the same manner, four different probe locations were defined (**Figure 2c**) to obtain stress and displacement results of the tested cross-section designs and allow a quantitative comparison of the effects of each individual design variable, their respective interactions and the overall behavior of the different design configurations. These probing locations will be used for all the analysis carried out in order to

A new design concept referred to as "Yoke plate cutting angle" is introduced as a design variable. This unique concept provides control over the stress distribution at the yoke plates interface by means of a resulting friction force generated at the surface-to-surface contact interface. The angled (non-horizontal) contact interface between the yoke plates and side yoke plates allows both plates to work in unison to carry the pressure load while still providing some accommodation for stress deflection by allowing slip plane movement between the plates. The yoke plates' cutting

*(a) General component layout and materials used, (b) general dimensions and design parameters and* 

Any composite overwrapped pressure vessel (COPV) design requires an analysis of the liner, the fiber overwrap, and the interaction between the two. COPV liners may be of ductile materials with only minimal load-sharing capabilities, such as ductile metal composites [11–19], glass fiber reinforced angle interlock composites [20–22], or carbon fiber reinforced composite oriented strand boards [5, 23–29]. The general layout and components of the baseline cross-section design (Section "A") are presented in **Figure 2a**. The outer diameter of Section "A" is roughly 60 cm. The design variables for the optimization of the circular cross-section "A" are presented in **Figure 2b**. These design variables are modified systematically throughout the design

**2. Optimal design procedure**

obtain consistent results.

**2.2 Yoke plate cutting angle concept**

**24**

**Figure 2.**

*(c) stress-probing locations.*

*Material properties of winding frame and yoke plates. (7075-T6 aluminum).*

*(a) Boundary conditions and mesh, (b) applied loads and (c) contact definitions.*

angle dictates the magnitude of the frictional force occurring at the interface. Thus, special attention must be paid to this dimension. A precise yoke plate cutting angle definition will allow contact related stresses to be just below the material's yield, while helping reduce the stress of the composite winding. Coulomb dry friction is a good starting point to approximate the maximum cutting angle that generates

a "stick" condition (no sliding) between the two surfaces. However, if no sliding occurs, stress concentration around the contact interface is bound to rise past the allowable limit—thus, some sliding must be ensured to provide stress relief.
