Spring elements in NASTRAN

In structural analysis, spring elements play a key role in simulating flexible connections, supports, joints, and contact interactions. MSC Nastran, a widely used finite element solver, offers several types of spring elements that allow engineers to model translational and rotational stiffness, damping, and even nonlinear contact behavior.

Whether you're modeling a simple connector, or a preload mechanism, choosing the right spring element is crucial for accurate results. Below, you'll find a concise guide to the most commonly used spring elements in Nastran, along with a comparison to help you select the best one for your application.

Element	Description
CELAS1	1D spring with stiffness defined directly between two grid points.
CELAS2	1D spring using a separate property (PELAS) to define stiffness.
CELAS3	Spring connected to ground with direct stiffness input.
CELAS4	Spring to ground, using a PELAS property.
CBUSH	Versatile 3D spring element with stiffness, .
CBUSH1D	Defines a one-dimensional spring-damper structural element.
CGAP	Nonlinear spring with contact behavior (can open/close).

Here are the property list of elements.

Property	Used With	Purpose
PELAS	CELASi	Defines spring stiffness
PBUSH	CBUSH	Defines stiffness, thermal expansion, etc.
PBUSH1D	CBUSH1D	Simplified 1D version of PBUSH.
PGAP	CGAP	Defines stiffness and contact values