A system for controlling displacement of a vulnerable component in connection with an impact event at the system. The system includes a frame structure, the vulnerable component, and a composite crush member (a) connected to the frame structure and the vulnerable component, forming a first close connection between the composite crush member and the vulnerable component and a second close connection between the composite crush member and the frame structure, (b) comprises primarily a polymer composite and is configured, and (c) is arranged in the system to fail in a predetermined manner in response to the impact event. The system also includes a retention feature configured and connected, directly or indirectly, to the vulnerable component and to the frame structure to, in operation of the system, maintain at least one of the first close connection and the second close connection during and following the composite crush member the impact event.