How to provide support and protection for automotive components (general structural parts)
The support and protection functions of automotive components, especially general structural components, are achieved through the synergistic effects of material selection, structural design, connection processes, and auxiliary systems. The following provides a detailed analysis from the perspectives of technical principles and practical applications:
The support and protection functions of automotive components, especially general structural components, are achieved through the synergistic effects of material selection, structural design, connection processes, and auxiliary systems. The following provides a detailed analysis from the perspectives of technical principles and practical applications:
1、 Material selection: laying the foundation for support and protection
1. High strength metal materials
Application scenarios: Core structural components such as frames, chassis, and body frames
Typical materials
High strength steel: yield strength ≥ 340MPa (such as hot formed steel, yield strength can reach 1500MPa), formed into complex shapes through cold stamping or hot forming processes to enhance structural rigidity. For example, the A-pillar and B-pillar of the vehicle are made of hot formed steel, which can reduce deformation during collisions and protect the passenger compartment.
Aluminum alloy: with a density about one-third that of steel, but a strength of up to 200-600MPa, it is used for engine mounts, suspension swing arms, etc., balancing lightweight and support. For example, the chassis structure of Tesla Model 3 extensively uses aluminum alloy die-casting, reducing weight while improving torsional stiffness.
Magnesium alloy: with a lower density (1.8g/cm ³), it is used for steering wheel frames, gearbox housings, etc. Its shock absorption performance is better than steel, which can reduce vibration transmission.
2. Composite materials
Application scenario: Non load bearing structures or lightweight components (such as door modules, luggage racks)
Typical materials
Carbon fiber reinforced composite material (CFRP): tensile strength ≥ 3000MPa, elastic modulus ≥ 230GPa, used for racing chassis and vehicle body frames, such as the carbon fiber passenger compartment of BMW i3, can withstand static pressure loads of more than 8 tons.
Fiberglass Reinforced Plastic (GFRP): Low cost, used for bumper frames and engine guards, with enhanced impact resistance through lamination process, capable of absorbing low-speed collision energy.
3. Special metals and coatings
Anti corrosion treatment: The surface of structural components is galvanized (such as hot-dip galvanizing, with a coating thickness of ≥ 8 μ m) or sprayed with epoxy resin to prevent rainwater and salt spray erosion and extend their service life. For example, the galvanized layer on the chassis longitudinal beam can improve the corrosion resistance of the components to over 10 years.
Damping material: embedding asphalt damping pads or butyl rubber in the steel plate interlayer to reduce vibration noise (such as car floor damping pads can reduce interior noise by 5-8dB).
2、 Structural design: Efficient support achieved through mechanical principles
1. Framework structure
Principle: Utilize the "beam column" system to distribute loads and improve stability through triangular/quadrilateral mechanical elements.
Typical applications
Frame longitudinal and transverse beams: The truck frame adopts a "trapezoidal frame", with the longitudinal beam (main beam) bearing vertical loads and the transverse beam (secondary beam) resisting torsion. For example, heavy-duty truck frames can carry more than 30 tons of cargo.
Cage structure of the car body: consisting of A-pillars, B-pillars, threshold beams, and roof crossbeams, the "cage frame" absorbs more than 80% of the impact energy through structural deformation sequence (such as the energy absorbing box collapsing first and the passenger compartment being subjected to force later) during collision.
2. Thin walled hollow structure
Principle: Utilizing "hollow sections" to enhance bending stiffness (such as circular/rectangular hollow tubes having better moment of inertia than solid rods) while reducing weight.
Typical applications
Suspension system: The piston rods of the front MacPherson suspension are made of hollow steel pipes, with a bending strength of 500MPa and a weight reduction of 40% compared to solid rods.
Anti collision beam: The car door is equipped with W-shaped or hat shaped section anti-collision steel beams, with a thickness of 1.5-3mm. During collision, energy is absorbed through section deformation. For example, the anti-collision beam of a certain vehicle model can withstand a lateral impact force of 15kN.
3. Biomimetic structures
Principle: Imitate the porous or honeycomb structure of biological bones to optimize material distribution.
Typical applications
Aluminum alloy wheels: The spokes adopt a "spider web" biomimetic design, and the material in the stress concentration area is thickened, which can withstand radial loads of over 700kg while reducing the moment of inertia.
Engine cylinder block: The internal structure is reinforced with "biomimetic honeycomb" ribs, which not only reduces weight but also enhances anti knock strength (for example, a certain inline four cylinder engine cylinder block reduces weight by 12% and increases stiffness by 25%).
3、 Connection process: Ensure structural integrity
1. Welding technology
Resistance spot welding: used for connecting body panels, with a single point welding strength of ≥ 3kN and a welding density of 8-12 points per decimeter to ensure body rigidity. For example, the number of welding points in the entire vehicle can reach 5000-7000, resulting in a torsional stiffness of 20000-30000N · m/°.
Laser welding: The weld seam width is 0.2-0.5mm, with a small heat affected zone, used for connecting the car roof and side panels. The welding strength is 30% higher than traditional spot welding, while reducing the risk of water leakage.
2. Bolt connection and riveting
High strength bolts: with a yield strength of ≥ 1000MPa (such as 10.9 grade bolts), used for connecting chassis suspension systems, with a pre tightening force control accuracy of ± 5% to ensure no loosening under dynamic loads.
Self piercing riveting (SPR): used for connecting aluminum alloy components, with a shear strength of ≥ 8kN for riveted joints, suitable for door modules, battery pack frames, etc., to avoid thermal cracking problems during aluminum alloy welding.
3. Adhesive bonding technology
Structural adhesive: shear strength ≥ 20MPa, used for body sealing and strengthening connections, such as the bonding between the roof and side panels, which can increase body stiffness by 15% and reduce wind noise.
4、 Auxiliary system: enhanced protection function
1. Energy absorbing device
Front/rear anti-collision energy absorbing box: adopts a "progressive collapse structure", which folds in a preset order during collision, and the energy absorption efficiency can reach over 90%. For example, the energy absorbing box of a certain vehicle model can absorb 60kJ of energy in a 40km/h collision, reducing the deformation of the passenger compartment.
Seat frame energy absorption: The seat rails are equipped with damping springs, which slide to absorb the inertial force of passengers during collisions, reducing chest injury value (THV) by 20% -30%.
2. Buffer and shock absorption
Rubber lining: used for connecting suspension systems, with a stiffness range of 5-50N/mm, to attenuate road vibrations (such as engine suspension lining can reduce idle vibrations by 3-5dB).
Air spring: used for commercial vehicle suspension, absorbs impact through gas compression inside the airbag, with a load adjustment range of 500-5000kg, and improves driving smoothness by 40%.
3. Electronic assistance system
Active suspension: By adjusting the suspension stiffness in real-time through sensors, the support force of the outer suspension is increased during high-speed cornering, reducing the roll angle by 20 ° and avoiding the risk of rollover.
Pre collision safety system: Predicting collisions through radar/cameras, tightening seat belts and adjusting seat positions in advance, reducing the impact force on passengers by 15% -20% during collisions.
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