This concept was first originated in the lightweight sports car, it’s not difficult to understand the advantages of light weight, and can lead to better handling, the power output of the engine is capable of producing higher acceleration. Since the vehicle light, and better performance at the start acceleration, braking when the braking distance is shorter.
1. lightweight Glossary
This concept was first originated in the lightweight sports car, it’s not difficult to understand the advantages of light weight, and can lead to better control power, the engine output can be generated higher acceleration. Since the vehicle light, and better performance at the start acceleration, braking when the braking distance is shorter.
With the “green energy” has increasingly become a topic of widespread concern, but also widely used in ordinary lightweight automotive sector, but also has excellent fuel economy performance while improving the handling. Automobile emissions and fuel consumption depends mainly on the total mass of the car’s engine, while maintaining the overall vehicle quality, performance, and cost the same or even optimized the premise of reducing the car’s own weight can increase the output power, reduce noise, improve handling, reliable , increased speed, reducing fuel consumption and emissions, improve security. Studies figures show that if 10% reduction in weight of automobile fuel efficiency may be increased by 6% -8%; if 10% reduction in rolling resistance, fuel efficiency can be increased by 3%; if the transmission efficiency of the device axle, the transmission 10 and the like to improve the %, fuel efficiency can be increased by 7%. Auto body about 30% of the total mass of the car, under no-load conditions, about 70% of the fuel used in body mass. Therefore, the body becomes lighter for vehicle fuel economy and vehicle stability control, crash safety are of great benefit. .
2 Comments lightweight vehicles
The main guiding principle: Based on the improved performance to ensure stable, energy-saving design of each assembly parts, continuous optimization model spectrum.
lightweight car, is in ensuring the strength and safety in the automobile premise vehicle curb weight as low as possible, thereby improving the vehicle’s mobility, reduced fuel consumption, reduced exhaust pollution. Experiments show that, when the automobile is reduced by 10 percentage by weight, fuel efficiency may be increased by 6 percentage -8 percentage; automotive trim reduction per 100 kg, can be reduced hundred kilometers 0.3-0.6 liter; 1 to reduce vehicle weight percentages, fuel consumption can be reduced 0.7 percentage. Currently, due to the need for environmental protection and energy saving, lightweight car has become the trend of the world automobile development.
3 main ways lightweight vehicles
① continuous optimization models mainstream automotive specifications, the specifications of the main parameters of the premise of the size retention, enhance the structural strength of the vehicle, reducing the amount of consumables;.
② use of lightweight materials. Such as aluminum, magnesium, ceramic, plastic, glass fiber-carbon fiber composite material or the like;
③ use of computer design. The finite element analysis, local reinforcement design;
④ using unibody thinned body panel material thickness.
wherein, the main current automobile lightweight measures are mainly use of lightweight materials.
4. Lightweight steel materials initiative
steel materials continue to play its cheap, mature technology advantages in competition with non-ferrous alloys and polymer materials by high strength and effective strengthening measures can give full play to its potential strength that is still by far the most used material in automobile production.
5. The high strength steel sheet Comments
25 Percent
is important in the car body weight, body weight material. 1990, 35 major steel companies world-wide cooperation to complete the “ultra-light steel auto body” (ULSAB-Ultra Light Steel Auto Body) issue. The subject of research suggests that the percentage of used steel body 90 is now mass-produced high-strength steel sheet (including a high strength, ultra high strength steel and the interlayer weight loss), reduced body weight 25 may be implemented at no additional cost percentage premise (4-door sedan as a reference), and the static torsional stiffness increased percentage of 80, 52 increase the percentage of the static bending stiffness, a first body structure 58 percentage increased modulus, impact meet all regulatory requirements. Of course, this is the outcome of a study of the practical application of high strength steel in the body of the vehicle has not yet reached such a high level. On the basis of the conventional IF steel have developed a high-strength IF steel and IF steel bake hardening while maintaining high moldability and improved dent resistance strength, create the conditions for the steel body to reduce the weight and thinning .
was added to precipitate Ti, Nb and V elements such as reinforcing steel tensile strength 500 ~ 750MPa, it may be used for wheels and other chassis parts.
recently developed multi-phase steel has considerable potential applications. Wherein the ferritic – bainitic steel intensity level of 500MPa, dual phase (DP) steel and transformation induced plasticity (the TRIP) steel strength level of 600 ~ 800MPa, complex phase (CP) steel is 1000MPa or higher intensity level. Forming properties of these steels is also very good. Japan’s Nissan Motor Company applied research conducted 590MPa grade high strength steel in the car body, they choose TRIP and DP steel sheet and DP steel bare steel sheet and galvanized using finite element analysis techniques to solve the problem of cracking during drawing and resilience, to optimize the welding parameters, by detecting the actual vehicle, stiffness and impact properties to meet the requirements, than with 440MPa grade 10kg weight down the steel sheet.
Laser Welding blanks (Tailored Blank) is a recently developed technology applications and lightweight steel sheet. In the vehicle body 18 ULSAB parts using this technique.
6. Detailed structural steel
The amount of steel material, although decreasing, but there is an amount of high strength steel increased considerably. High strength structural steel design the parts more compact and small, which contributes to weight reduction of an automobile.
(1) a spring
The most effective method is to increase the weight of the suspension spring allowable design stress of the spring. However, to achieve weight reduction in such high stress, high strength material is essential. Based on the traditional Si-Mn spring steel by lowering the C and alloying elements Ni, Cr, Mo and V, etc., to develop the strength and toughness of the steel are high, up to 1270 MPa allowable stress design, such a spring application of steel 40 percent weight reduction can be achieved. Nb is added in the conventional Cr-V steel-based spring steel may improve the anti-delayed fracture properties, improved binding roll forming austenite, the tensile strength of the steel can reach 1800MPa level.
Si-Cr steel valve spring with added V, ensuring toughness through grain refinement by increasing C to increase the strength. After such an improved, high cycle fatigue strength of the spring about8 the percentage of increase, 15 percent reduction in weight can be achieved. Finite element analysis, the coil spring, a lemon-shaped cross-sectional outer stress distribution uniform spring wire to be developed, so that the spring 7 percent to achieve weight reduction. Effective way to improve the fatigue strength of the spring is spring nitriding treatment and shot peening. Shot peening of the spring, in addition to a conventional stress shot peening and the development of a two-stage shot peening. And blasting the composite nitride may be used.
(2) gear
automotive engine has a tendency of high power, and compact size of the actuator has a tendency. This will inevitably increase the load drive gear, thereby bending fatigue strength requirements and the contact fatigue strength gear steel have been increased.
increasing the content of alloying elements in the steel Ni, Cr, Mo and the like can be improved permeability and strength of quenched steel gears, but simply by cutting alloying element to strengthen steel gear steel causes deterioration, the heat treatment process complex, raw material costs and production costs will be greatly improved. Carburized gear, in order to prevent or reduce the abnormal layer is reduced by P and Si content in the steel, Mo amount was increased percentage of 0.35 weight percent to 0.45, and by using a modified carbonitriding process. Improved steel kind can impact the life of the gear increases 3 to 5 times, if the abnormal layer above the steel plus strong reduction of surface blasting, can improve the fatigue limit gear 20 percentage to 30 percentage.
Gear non-metallic inclusions in steel is the starting point of fatigue cracks, a powerful strengthening effect reduces peening, developed for this purpose gear steel of high purity. SCM420HZ steel for example, the oxygen concentration falls 9ppm less, the phosphorus concentration falls 90ppm or less, to reduce surface anomalies and the low Si high Mo layer than steel, tooth root bending fatigue life of 10 percentage to 17 percentage increase, the contact 25 percentage increase fatigue life.
7. Explanation of high strength cast iron
Iron Due to many advantages in terms of cost and performance, is still in place in automotive materials. Cast iron materials more progress so that application in the car there is a new bright spot.
(1) ductile iron
ferritic spheroidal graphite cast iron up to 500 MPa or a tensile strength, high toughness, so much for the chassis parts, and even some models as a knuckle and other security elements.
higher strength pearlitic ductile iron, in place of some of the parts may be forgings. 4-cylinder car engine crankshaft with counterweights of ductile iron plus fillet rolling strengthening, has become the standard technology the United States, Germany, France and other auto manufacturers. Ductile iron due to density ratio of about 10 percentage of small steel, ductile iron and steel, it can be to produce a certain effect in weight reduction.
austempered ductile iron (ADI-Austempered Ductile Iron) having high strength and toughness and plasticity, ADI grades U.S. and German standard manufacturing, the highest intensity level reached 1400 MPa, over the quenching strength level of the steel and hardened steel. ADI may be used instead of steel automotive wheel, all-wheel drive double rod, knuckle arms, engine timing gears, crankshafts and connecting rods and the like. By physical measurements, instead of forged steel crankshaft 10 weight percentage can be lowered, instead of an aluminum alloy can lower each wheel hub laden weight 0.5kg.
(2) vermicular cast iron
vermicular graphite iron (Vermicular graphite cast iron), also known as tight graphite cast iron (Compacted graphite cast iron), which mechanical – Physical Properties and casting properties between gray and ductile cast iron, it is suitable for producing high strength is required to withstand thermal cycling and load the parts, such as a cylinder block, a cylinder head, an exhaust manifold and the brake drum or the like.
found that vermicular graphite iron and ductile iron at the same time, but the process more difficult to control creep and applicationsLimited, Sinter Cast process control system opens up broad prospects for the application of vermicular iron. Ford Motor Company from 1996 began to use this system produces engine cylinder block. Ratio of vermicular iron cylinder block is said gray cast iron cylinder block 16 weight percentage drop, while the structural rigidity is increased percentage of 12 to 25 percentage. Compacted iron manufacturing a cylinder block can also improve the friction and wear properties, reduce vibration and noise, improve emissions.
8. Detailed sintered materials
M materials near net shape component DOF characteristic Japanese powder sintering process, which in automotive applications there is an increasing trend, especially iron-based application of sintered powder materials in complexity of the structure required more and more higher strength.
a hollow powder metallurgy assembled camshaft in recent years a new product, which is made of an iron-based sintered materials of the cam, and then sintered or mechanically by way of a fixed component of the hollow pipe. Compared to conventional forging or cast iron, the weight can be reduced 25 to 30 percentage percentage. Such has been used in high-speed camshaft gasoline engines, with? Increasingly demanding service conditions of the diesel engine camshaft, powder metallurgy hollow camshaft trend towards diesel engines.
has been successfully applied powder forged connecting rods, the lower primary sintered powder metallurgy recently developed technology rod production costs, 11 percent reduction in weight can be achieved. German Opel company installed on the 2.0L OHC engine with 300,000 km of results were normal.