In modern engineering design, movable structures are widely used in architecture, machinery, aerospace, robots, bridges and other fields. The core of movable structure lies in its flexibility and adaptability, and the key to realize this kind of motion performance lies in the design of "connection points". Good connection points can not only ensure the stability of the structure, but also realize smooth movement and reliable bearing capacity. Therefore, this paper will focus on the design principles, types and optimization methods of connection points in movable structures.

First of all, the function of connection points in movable structure is mainly reflected in three aspects: transmitting force and moment, allowing relative movement, and maintaining the stability and safety of the whole structure. Therefore, mechanical properties, material selection, freedom of movement and other factors must be considered comprehensively in the design.

Common connection forms include hinge connection, sliding connection, ball hinge connection, flexible hinge and so on. Hinge connection is suitable for plane rotation, such as the connection between door leaf and door frame; Sliding connection is suitable for linear movement, which is common in telescopic structures; Spherical hinge connection can realize multi-directional rotation and is widely used in mechanical arms and space structures. Flexible hinges use the elastic deformation of materials to realize small-angle movement, which is suitable for precision instruments and micro-structures.

When designing connection points, the following principles should be followed:

1. Degree of freedom control: reasonably set the degree of freedom of connection points according to structural requirements to avoid over-constraint or under-constraint;
2. Matching of materials and processes: selecting materials with sufficient strength and wear resistance, and optimizing the geometric shape of the connection point in combination with the manufacturing process;
3. Force analysis and strength check: through finite element simulation or mechanical analysis, ensure that the connection point can bear the expected load;
4. Maintenance and durability considerations: For long-term movement connection points, lubrication, dustproof and replaceable design should be considered to prolong service life.

In addition, with the development of smart materials and adaptive structures, some new connection methods are gradually introduced, such as magnetorheological fluid connection and shape memory alloy drive connection. These technologies provide a higher level of flexibility and intelligence for movable structures.

To sum up, the design of connection points is the key to the success of movable structures. In the design process, engineers need to comprehensively apply multidisciplinary knowledge such as mechanics, material science, manufacturing technology, etc., so as to ensure that the connection point not only has good sports performance, but also has sufficient safety and durability. In the future, with the continuous emergence of new materials and new processes, the design of connection points will also develop in a smarter, more efficient and lighter direction.