﻿ Line results: Forces

# Line results: Forces

### Effective tension and wall tension

Available at mid-segment points and line ends. The structural force along the line axis. Positive values denote tension, negative values compression.

The reported wall tension is the total wall tension, $T_\mathrm{w}$, scaled by the tensile stress loading factor, or automatically scaled if homogeneous pipe additional bending stiffness is in use.

The line pressure effects topic explains the difference between the effective tension, $T_\mathrm{e}$, and the wall tension, $T_\mathrm{w}$. In particular, if the line type stress diameters differ from the outer and inner diameters, see the note on that page.

### Normalised tension

Defined as effective tension divided by allowable tension. Available at mid-segment points and line ends; not available if the allowable tension is '~'.

### Twist induced tension

Available at mid-segment points only, and only for lines with torsion included. This is the tension / torque coupling contribution to tension, given by $k_\mathrm{tt} \tau / l_0$.

### Sidewall pressure

Defined as $T_\mathrm{e}|\vec{c}|$, the product of effective tension and the magnitude of curvature.

 Note: Although this quantity is named pressure, it is not a true pressure value, having units of force per length.

### Shear force, x shear force, y shear force, shear force component, in plane shear force, out of plane shear force

Available at mid-segment points and line ends. The magnitude of structural force normal to the line axis, its components in the local x and y-directions, its component in the user-specified local direction theta and its components in the in-plane and out-of-plane directions.

The out-of-plane direction is normal to both the line's axis (at the specified arc length) and the vertical direction. The in-plane direction is normal to both the line's axis and the out-of-plane direction.

If the line's axis is vertical then these directions are ill-defined and therefore no values can be reported.

### Vortex force magnitude,Inline vortex force, transverse vortex force,GX vortex force, GY vortex force, GZ vortex force

Available only at nodes that use one of the time domain VIV models. The magnitude of the lift and drag force per unit length of line, and its components in the VIV directions and global axes directions. For details, see the documentation of the relevant time domain VIV model.

### Inline drag amplification factor

Available only at nodes that use one of the wake oscillator VIV models. The instantaneous value of the inline drag amplification factor.