JPS58118340A - Leaf spring made of fiber reinforced resin - Google Patents

Abstract

PURPOSE:To improve the compressive strength and to equalize the fatigue strength at each part of a leaf spring by giving an initial tensile stress to a surface layer of a reinforced fiber at which a maximum compressive stress is produced, before shaping. CONSTITUTION:A leaf spring 1 which is made of fiber reinforced resin is made up by reinforcing matrix resin P with reinforced fiber F such as carbon fiber C. Before shaping, an initial tensile stress is given to reinforced fiber F, that is, carbon fiber C which is mixed into a surface layer 1a at which a maximum compressive stress in the spring 1 is produced. This may reduce the compressive stress which is produced when a bending load is exerted on the leaf spring 1.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a leaf spring made of fiber-reinforced resin, and in particular to a fiber-reinforced resin that is molded with initial tensile stress applied to reinforcing fibers to reduce compressive stress and improve strength. Regarding leaf springs.

Conventionally, various types of leaf springs made of fiber-reinforced resin have been proposed, but l* leaf springs are made by reinforcing IJ Fuchs resin with reinforcing fibers such as charcoal aC fibers and glass fibers. Carbon fiber is particularly strong in tension, and glass fiber has high hardness and high resistance to damage.Although they are used depending on their characteristics, both types of reinforcing fibers are difficult to compress. The strength must depend entirely on the matrix resin - Uta 0 However, the compressive strength of the matrix resin is much lower than that of copper.For this reason, conventional fiber-reinforced resin leaf springs break due to stress and tensile stress. The electrical equipment entered the surface layer and broke when the cable was loaded, which caused maximum compressive stress, and the cables were found to be less durable than copper plates.

The present invention has been made in order to eliminate the drawbacks of the above-mentioned prior art, and its purpose is to provide a fiber-reinforced resin leaf spring in which a matrix resin is reinforced with reinforced fibers. By applying an initial tensile stress to the reinforcing fibers disposed in the surface layer where the maximum compressive stress occurs and forming the curve, the compressive stress during loading can be reduced compared to the tensile stress. , the compressive strength of the M-fiber-reinforced resin leaf spring is increased to the same level, and the fatigue of each part of the leaf spring is increased (9), except for the drawback that the strain caused by stress always occurs from the compression side.9)
'It is to equalize AE to 4.

★The present invention, in a fiber-reinforced resin plate spring in which a matrix @ fat is reinforced with reinforcing fibers such as carbon tracks @ L, has an initial tensile strength in the reinforcing fibers blended on the surface where the maximum compressive stress occurs. The invention is characterized by being molded by applying stress to suppress the compressive stress generated during the bending load of the plate spring. In rivet 1 and Figure 2, edge: similar spring made of reinforced resin 1tri, ma) IJx resin P reinforced with carbon fiber C thick 541 katentoge F, and its maximum pressure is , reinforcing fibers F blended into the surface Jmla where force is generated
In other words, the carbon fiber C is molded by giving an initial tensile stress, and the method of giving an initial tensile stress of 0 is achieved by reducing the compressive stress that occurs during bending load of the fiber-reinforced lamina plate gene 1. The elongation rate is set to 1 so, preferably about 04 chi, since it will break when it reaches 9% in the k element ##cbcos combination. As a result, the initial tensile stress σ, 0 is approximately 40 k
g/m-, this is the thinnest carbon fiber C1 in the surface layer 1 m of the fiber-reinforced resin leaf spring 1 shown in FIG. The elongation rate of the charcoal 1g fibers C, , C, may be reduced so that the initial tensile stress gradually decreases as the center layer 1b approaches.

On the other hand, in the illustrated embodiment, no initial tensile stress is applied to the carbon fibers C of the surface layer IC where the maximum tensile stress occurs when a load is applied, so the carbon fibers C of the surface layer 1c on the tensile side are drawn thickly in the figure. Another method is to apply this initial tensile stress to

The present invention is configured as described above, and its operation will be explained below. As shown in FIG. 1, when a bending load W is applied to the fiber-reinforced resin leaf spring 1 of the present invention from the lower center, a reaction force R acts on both ends, and the fiber-reinforced resin leaf spring 1 is The carbon fibers C of the surface layer 1a are bent from an initial concave state to a flat or upwardly convex state, but since an initial tensile stress is generated in the carbon fibers C of the surface layer 1a, as shown in FIG. When the strain 1 of the resin plate spring 1 is 0, the tensile stress 't is not 0 but -, and the stress-strain diagram shows the tensile stress σ, = σ1. As the bending load increases, the compressive strain increases to a constant value, i.e. Δ
No compressive stress ・ is generated in the surface layer 1a until it reaches ε ◎ Then, when the compressive strain e reaches Δε, the initial tensile stress ′1 ・ disappears, and as the load increases further, the strain stress increases. A compressive stress of 0 is generated in the surface layer 1a for the first time, but compared to the conventional example in which an initial tensile stress of 0 is not applied, the maximum compressive stress of 0 when a severe bending load is applied is reduced by an amount of the initial tensile stress, Favorable results are obtained.

And uniformity of fatigue strength can be achieved. Furthermore, the surface layer 1a
The initial tensile stress in the glaze can be applied in different ways as one approaches the center layer 1b. Furthermore, by applying an initial tensile stress 'Im to the carbon fibers C of the surface layers 1a and 1c, the shape of the fiber-reinforced resin plate spring 1 in its free state can be changed to an appropriate shape, for example, an upwardly concave shape as shown in Fig. 5g1. can be kept.

Since the present invention is constructed and operates as described above, the matrix resin is reinforced with reinforcing fibers such as carbon fibers! In the leaf spring made of reinforced wood Bb, the reinforcing fibers placed in the surface layer where the maximum compressive stress occurs are given initial tensile stress and molded, so the compressive stress during bending load can be reduced compared to the tensile stress. It is possible to improve the compressive strength of this leaf spring made of rice fiber reinforced street oil, and it is possible to obtain the effect of being able to eliminate the drawback that osteoclast fracture always occurs due to compression force. Moreover, the effect of equalizing the fatigue strength in each part of the fiber-reinforced resin front plate spring can be obtained.

[Brief explanation of the drawing]

The drawings relate to embodiments of the present invention, and FIG. 1 is a 11i plane view of a fiber-reinforced resin leaf spring showing a state where a bending load is applied.
Figure 2 is an enlarged partial cross-sectional view of the fiber-reinforced resin leaf spring.
FIG. 3 is a stress-strain diagram. 1 is a leaf spring made of fiber-reinforced resin, 1aVi is the surface layer where the maximum compressive stress occurs, C is carbon fiber, F is reinforcing fiber, P/I'i
Matrix resin, W is bending load to = compressive stress, σ
[Stock] is tensile stress, (1st ward is the initial tension period, Kademeru.

Claims (1)

[Claims] In a fiber-reinforced resin leaf spring in which a matrix resin is reinforced with reinforcing fibers such as carbon fibers, the reinforcing fibers blended at least on the surface where the maximum compressive stress occurs are given an initial tensile stress to form the leaf spring, and the leaf spring is bent. A fiber-reinforced resin leaf spring characterized by reducing compressive stress generated during loading.