Variable Cross-Section Fiber Composite Boom Arm for Concrete Pumps
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Solution Overview
Problem
The high weight of elbowed boom arms in mobile concrete pumps, made from steel, limits the number of boom arms and maximum height due to weight constraints, hindering their compact folding and mobility.
Innovation Solution
The boom arm is designed from fiber composite material with a cross-sectional shape that adapts to loading conditions, featuring a wider section in the elbowed region and a constant height over its length, optimizing stiffness without increasing wall thickness, and using continuous fiber-reinforced materials for reduced weight and improved structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If elbowed boom arms are made from steel with sufficient wall thickness to absorb forces, then structural strength is ensured, but weight becomes not inconsiderable and limits the number of boom arms
Solution Approach 1:
The boom arm is made from fiber composite material instead of steel. This composite material provides sufficient structural strength to absorb forces while significantly reducing the weight of the boom arm, resolving the contradiction between strength and weight.
Solution Approach 2:
The cross-section of the boom arm is varied along its length: beyond the elbowed region the height is greater than the width, while in the elbowed region the width is greater than or equal to the height. This local adaptation of cross-sectional dimensions optimizes the strength-to-weight ratio in different regions.
2Length of moving object
If the number of boom arms is increased to achieve greater height, then maximum height is improved, but total weight increases and may exceed maximum permissible axle load
Solution Approach 1:
By using fiber composite material for the boom arms, the weight of each individual boom arm is reduced. This allows for an increased number of boom arms to be installed without exceeding the maximum permissible total weight or axle load, thereby achieving greater maximum height.
3Stability of the object's composition
If wall thickness is increased to maintain stiffness in elbowed region, then structural stiffness is improved, but weight increases
Solution Approach 1:
The cross-sectional dimensions are locally adapted: in the elbowed region where torsional loads act, the width is made greater than or equal to the height. This local geometric optimization provides sufficient stiffness without requiring increased wall thickness, thus avoiding additional weight.
Data Source
AI summary
The invention relates to a boom arm for mobile concrete pumps and to a mobile concrete pump. The boom arm, having a first and second end, wherein at least one elbowed section, in which the main bending loads which occur during proper use act as torsional loads, is provided between the first and the second end of the boom arm, is made from a fiber composite material, wherein beyond the elbowed region the height of the boom arm in cross-section is greater than the width of the boom arm in cross-section and in the elbowed region the width of the boom arm in cross-section is greater than or equal to the height of the boom arm in cross-section. A concrete pump with a placing boom, arranged on a substructure, comprising at least two boom arms, at least one of which is designed according to the invention.