Overview of Automobile Frame Knowledge

Type of frame:

(1) Traditional frame: It adopts a non load-bearing body and is applied to trucks, off-road vehicles, etc;

(2) Load bearing body: mainly used for sedans, which also serves as a frame.

1.2 Classification of frame:

Frames can be divided into three categories:

1. Edge beam frame: The edge beam frame is composed of two longitudinal beams located on both sides and several crossbeams, which are connected to a sturdy rigid frame by riveting or welding.

Center beam frame: The center beam frame has only one longitudinal beam that runs through the front and rear at the center, hence it is also known as a spine frame.

3. Integrated frame: The front of the frame is a side beam type, and the rear is a center beam type. This type of frame is called an integrated frame (also known as a composite frame). It has both the characteristics of a center beam and edge beam frame.

1.3 Development of frame:

2、 Frame structure design

The frame should achieve a reasonable goal in structural layout, what is reasonable? The so-called rationality refers to achieving ease of installation and disassembly on the premise of meeting the requirements of sufficient strength, stiffness, and overall vehicle layout of the frame itself. Whether the frame structure is critical or not needs to be analyzed from two aspects, namely the strength and stiffness of the frame's own key structure, and the function of the chassis components to assist the key structure.

1. The force on the frame structure:

To evaluate the design and structure of a vehicle frame, it is important to have a clear understanding of the various forces that the frame must withstand while driving. If the frame has poor toughness in some aspect, even with a good suspension system, it cannot achieve good handling performance. And the frame has to face four types of pressure in actual environments.

a. Load bending:

The suspension weight of some cars is borne by the frame and transmitted to the ground through the axles. And this pressure will mainly be concentrated at the center point of the wheelbase. Therefore, the longitudinal and transverse beams at the bottom of the frame generally require strong strength. As shown in the following figure, the bending stiffness calculation conditions of the frame are calculated using CAE analysis methods:

b. Non horizontal twisting:

The rear diagonal wheels are rolling due to unevenness on the road, and the beams and columns of the frame are subjected to this longitudinal twisting pressure, as if you were twisting a plastic sheet into a spiral shape.

c. Lateral bending:

The so-called lateral bending refers to the tendency of the car's weight inertia (i.e. centrifugal force) when entering a bend to throw the body out of the bend, and the grip of the tires will react with the road surface, causing two opposing pressures to twist the frame laterally.

d. Horizontal diamond twist:

When a vehicle is in motion, each wheel will bear different resistance and traction forces due to different road surfaces and driving conditions (such as road laying, bumps, obstacles, and entry and exit corners, etc.), which can cause the frame to push and pull in the horizontal direction, leading to deformation. This situation is like pulling a rectangular shape into a diamond shape.

2. Longitudinal beams, crossbeams, and their connections:

The connection method is shown in the following figure:

3. Common materials for frame:

3、 Fundamentals of Frame Manufacturing