Principle and Approach for Determining the Reasonable Cross-Section of the Solid-Web Double-Beam Component

Solid-web double-beam component is widely used in the dipper handle of excavator, whose mechanical behaviour belongs to compression-bending member and mainly satisfies the strength requirement. In this paper, it starts from the design principles of steel structure and elastic theory, determines the dimension of the main cross-section and the reverse tube under guidance of optimization, and provides initial data for the detailed design. The method has common direct sense.


Foreword
Solid-web double-beam component is widely used in the dipper handle of mechanic excavators, whose mechanical behavior belongs to compression-bending member and mainly satisfies the strength requirement. In initial design, how to use its basic data, determine its reasonable cross-section dimension and provide initial data for the detailed design, designers are got into trouble. Thus, determine the reasonable dimension of the main cross-section from the design principles of steel structure under guidance of optimization and taking the example of excavator dipper handle.
To determine the cross-section of composite beam, the overall design requirement of components shall be comprehensively considered to meet the requirement of strength and economy. It is the issue of optimization.

Requirements for strength
Where the ratio of length l and height h of a component / 5 l h > , it can be regarded as a beam. According to strength requirement of beam,

Function expression of beam dead weight
Beams with wide universality in components are composite I beams and composite box beams. Excavator movable arm belongs to composite box beam, generally composed of flange plate, web plate and web stiffener. Gross mass of beam G is the summation of flange plate weight G 1 , web plate weight G 2 , web stiffener weight G 3 and connecting weld joint weight G 4 .
Wherein, (1) Determine formula G σ of beam dead weight according to strength requirement: To get min G σ , supposing

Applied Mechanics and Materials Vols. 215-216
Dipper handle of mechanical excavator plays the role of stress and bending mainly, whose torsion is sustained by reverse tube. Thus, Make substitution (13) into (12) and (14), Then cross section h σ , determined by external load and basic parameters, can be obtained.
A can be calculated by making substitution of h σ into (8) and (5).

Determine the reasonable cross section of hopper handle 2.1 Determine the center width between two hopper handles
Inside width of hopper handle is determined by the distance between hopper handle and hopper hinge point which exerts a tremendous effect on hopper intensity. Thus, the center width of two hopper handles can be determined by hopper hinge point distance.
Hinge point between hopper handle and hopper is located the rear wall of hopper. Thickness of rear wall is much smaller than width and length of rear wall, simplified as simply support overhanging beam structure of both ends. Normal component of force of load (Including soil counter-force) acts at hopper rear wall and is considered as uniformly distributed load, as shown in

Fig.3: Force diagram of hopper handle
Hopper handle design [1] includes structure form of hopper handle, hopper handle length, cross-sectional design and cross-sectional design of reverse tube.
Hopper handle is push-type gear rack, solid-web double-beam component, added with ribbed slab along its cross section direction, welded cylinder at front hopper handle next to hopper used for anti-torque.

(1)Assumed conditions
Assumed conditions include the following. ①Considering hopper body stiffness is much larger than hopper handle stiffness.

(4) Width of hopper handle
Width of single hopper handle is determined by the width of pinion mate.

Calculation of reverse tube
Reverse is caused when T1 and 2 0 k w r b acting on meshing point between hopper handle and pushing gear is simplified on hopple arm central plane. Function of reverse tube is anti-torque. For easy calculation, regard reverse tube as rectangle uniform section.