Calibrated Frame Stiffness Gradient in Agricultural Sprayer
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Solution Overview
Problem
Designing a vehicle frame for self-propelled agricultural product applicators that achieves high ground clearance while maintaining lightweight construction and sufficient bending and torsional stiffness to navigate uneven terrain without damaging crops, while also being cost-effective and producible.
Innovation Solution
Attaching a series of cladding plates to the external surface of a tubular frame member with varying thicknesses and peripheral shapes to create a calibrated stiffness gradient, and using a raised trailing bead to enhance stress distribution, thereby optimizing the frame's stiffness and weight distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If tubular frame members with high section modulus are used to achieve sufficient bending and torsional stiffness, then the frame can navigate uneven terrain without damaging crops, but the frame weight increases, requiring larger suspension components and reducing payload capacity
Solution Approach 1:
The frame employs varying wall thicknesses in different sections of tubular members, with thicker walls positioned strategically at high-stress locations and thinner walls in low-stress areas. This local quality variation maintains sufficient bending and torsional stiffness where needed while reducing overall frame weight, thereby improving payload capacity without compromising the ability to navigate uneven terrain.
Solution Approach 2:
The invention utilizes controlled variations in wall thickness as a key parameter to optimize the strength-to-weight ratio. By changing the thickness parameter locally rather than uniformly throughout the frame, the design achieves calibrated stiffness gradients that provide necessary structural integrity while minimizing weight, thus resolving the contradiction between strength and weight.
2Weight of moving object
If the frame is made lighter to reduce sprung weight and maximize payload, then suspension components can be smaller and payload capacity increases, but the bending and torsional stiffness becomes insufficient for navigating uneven terrain at high speed
Solution Approach 1:
Rather than uniformly reducing weight, the frame applies local quality enhancement by concentrating material thickness in specific high-stress regions while maintaining lighter construction in other areas. This strategic distribution of mass reduces overall sprung weight while preserving the bending and torsional stiffness necessary for high-speed operation on uneven terrain.
Solution Approach 2:
The frame construction utilizes composite structural approaches combining tubular members with varying wall thicknesses and strategic reinforcement elements. This composite design philosophy allows optimization of weight and stiffness independently in different regions, achieving lightweight construction that does not sacrifice the structural integrity needed for navigating rough terrain at speed.
3Ease of manufacture
If uniform thickness tubular frame members are used, then manufacturing is simpler and cost-effective, but the frame cannot achieve calibrated stiffness gradient to optimize stress distribution
Solution Approach 1:
The frame is segmented into multiple sections with different wall thickness characteristics, allowing each segment to be optimized for its specific stress conditions. This segmentation into varying thickness zones enables calibrated stiffness gradients while maintaining manufacturing feasibility through standardized production techniques for each segment type.
Solution Approach 2:
The invention implements local quality variation through controlled thickness changes in different frame sections. This approach maintains ease of manufacture by using conventional tubing with specified wall thickness variations, while achieving superior stress distribution through the calibrated stiffness gradient created by these local thickness differences.
4Length of moving object
If high ground clearance is achieved through frame design, then the applicator can move through standing crops without damaging them, but the frame must be heavier to support the high-boy configuration and maintain stability
Solution Approach 1:
The high-boy frame utilizes local quality optimization by concentrating structural reinforcement only where required to support the elevated configuration and maintain stability. Rather than uniformly increasing weight throughout the frame, thickness variations are applied strategically at critical support points and joints, enabling high ground clearance while minimizing overall frame weight.
Solution Approach 2:
The frame employs asymmetric thickness distribution tailored to the specific loading and stability requirements of the high-boy configuration. This asymmetric design places heavier sections where structural support is most needed for the elevated ground clearance geometry, while using lighter sections elsewhere, thus achieving high ground clearance without excessive weight penalty.
Data Source
AI summary
A vehicle frame having a calibrated frame stiffness gradient is provided by fixedly attaching a series of cladding plates to an external surface of a tubular member of the frame, with the series of cladding plates including at least one immediately preceding cladding plate and one successive cladding plate. The cladding plates have thicknesses and peripheral shapes that are cooperatively configured to provide the desired stiffness gradient in the frame member. A trailing raised bead extending from the last cladding plate in the series along the surface of the frame member provides a further means for achieving the desired stiffness gradient.