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Final Presentation. Team CNH. Raquel Ciappi Brad Miller Stephen Petfield Chris Uthgenannt. Background Information. Case New Holland (CNH) is the number one manufacturer of agricultural tractors and combines Products include: Harvesting and seeding equipment Balers

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Final presentation

Final Presentation

Team CNH

Raquel Ciappi

Brad Miller

Stephen Petfield

Chris Uthgenannt

Background information
Background Information

  • Case New Holland (CNH) is the number one manufacturer of agricultural tractors and combines

  • Products include:

    • Harvesting and seeding equipment

    • Balers

    • Disc mowers and mower conditioners

Disc mowers
Disc Mowers

  • Disc mowers are used to cut crops such as alfalfa and hay before baling

  • Mowers utilize 4-6 oppositely rotating blade heads aligned along a shaft underneath the mower’s hood

  • Under normal operating speeds blade heads rotate at 3000 rpm

  • A protective curtain on the mower is used to provide shielding from high-speed projectiles

  • Conditioning rolls are used to crush crop stems and decrease drying time

Problem definition
Problem Definition

  • Before cutting, crops must pass by the protective curtain

  • Current curtain exerts a large force on crops causing a knockdown effect and lower quality cut

  • To eliminate this effect farmers are mowing with the mower deck in a raised position

  • Raised deck poses safety hazards from high speed projectiles

Project scope
Project Scope

  • Identify causes of knockdown force (KDF)

  • Create testing methods to quantify knockdown force

  • Design a new shielding system to attenuate knockdown force while maintaining adequate projectile protection

Wants and metrics
Wants and Metrics

  • Using discussions with CNH a set of wants was developed

  • Metrics were created as a basis for design evaluation

Design proposal
Design Proposal

  • Possible areas for modification of existing design to decrease knockdown:

    • Turbulent airflow underneath mower

    • Curtain material

    • Mounting system

  • Each factor is assessed using engineering analysis and conducting tests in a controlled environment

  • Key findings implemented in a new design prototype

Proposed modifications
Proposed Modifications

  • Employ air vents and mesh curtain to control turbulent airflow generated by mower

  • Implement lighter curtain material

  • Modify mounting configuration for hinge system

Airflow analysis
Airflow Analysis

  • Preliminary airflow analysis was conducted to examine turbulent airflow effects on curtain

  • Mower curtain modeled as a flat plate subjected to normal flow

  • Drag effects exert significant outward force on mower curtain (22.3 lbf)

  • Further experimental testing needed to fully understand airflow effects

Airflow testing
Airflow Testing

  • Initial testing examined airflow effects by measuring airflow velocities using an anemometer

  • Measurements taken at 10 different locations along lower and upper halves of curtain

  • 2 sets of trials conducted:

    • Closed deck hood

    • Open deck hood

Preliminary results











Preliminary Results

  • Similar patterns seen for each testing configuration

  • Air velocities projected outward suggest use of mesh at high velocity locations

Airflow kdf contribution
Airflow KDF Contribution

  • Conduct testing measuring the force needed to deflect curtain

  • Measurements taken with mower on and off

  • Measurements at 4 locations along curtain

  • Examines the role of airflow with respect to knockdown force

  • Results show airflow is a significant factor in causing crop knockdown

Mower deck ventilation
Mower Deck Ventilation

  • Another method to control airflow is implementation of vents on the mower deck

  • Examining blade head air direction, vents installed at optimal locations on mower deck

  • To evaluate vent effectiveness air velocities were measured at:

    • Bottom of curtain

    • Each vent location

  • Different vent configurations employed to examine variations in air velocity

Ventilation test results






Ventilation Test Results

  • Results suggest that no vent combination reduces air velocity

  • Velocities at bottom of curtain actually increased with vents

Cfd analysis
CFD Analysis

  • Computational Fluid Dynamics (CFD) performed

  • Confirms testing results and further explores turbulent air patterns

  • Simple simulation in COSMOS Flow Works

  • CFD results show little or no velocity near deck hood

  • Highest velocities point directly towards curtain

Airflow conclusions
Airflow Conclusions

  • Airflow is a significant factor in crop knockdown

  • Testing and CFD results demonstrate that vents do not control airflow

  • Modifying turbulent air effects of mower is complex and not feasible

  • Employing mesh curtain sections still a viable method to reduce knockdown force

Proposed material design
Proposed Material Design

  • Curtain design consists of a non-homogenous solid material lighter than existing design

  • Sections of mesh material employed at areas with high air velocities

  • Conduct testing to:

    • Ensure mesh passes ISO safety standards

    • Select a material to lower knockdown force

Etch test
Etch Test

  • Modified ISO standards test to determine projectile ejection patterns

  • Mower curtain replaced by layers of plywood, Styrofoam, and paper

  • Mower pulled by tractor over piles of sand, gravel, and water mixture

  • Projectile ejections recorded by indentations or projectiles lodged in Styrofoam

Mower deck


Sand and gravel


Mower blades


Etch test results
Etch Test Results

  • Styrofoam divided into 6 sections

  • Projectile impacts were counted and separated into large and small categories

  • Large projectiles averaged 28 strikes per section

  • Indicates that solid curtain material must be used



  • Add some kind of slide so that we can transition from material to mounting without losing the audience because we haven’t discussed a way to evaluate the knockdown force of different materials

Mounting method
Mounting Method

  • Three new mounting methods proposed:

    • Conventional hinge

    • Spring hinge

    • Counterweight hinge

  • Preliminary analysis of each hinge design was conducted to predict each system’s performance

Mounting analysis
Mounting Analysis

  • Assuming no curtain deflection, equations were derived for each mounting system

  • Illustrate behavior of knockdown

    force with varying angle (taken

    from horizontal)

    Basic Hinge Spring Hinge Counterweight

Mounting analysis results
Mounting Analysis Results

  • Derived equations were

    used with approximate

    values for each parameter

  • Force vs. Angle graph

    constructed to compare


  • Predicts performance of

    each mounting configuration

  • Spring hinge and counterweight most appealing designs

  • Minimizing both force and angle will produce best results

Component integration
Component Integration

  • The optimal curtain material and mount need to be determined

  • Testing apparatus designed to quantify knockdown force of various materials and configurations under controlled conditions

  • Eliminates turbulent air flow variable

  • Knockdown Force Test (KDF Test)

Knockdown force test



Load Cell

Knockdown Force Test

  • Apparatus utilizes load cell to measure force exerted by moving curtain assembly

  • Electric motor provides constant curtain speed of 0.642 mph

  • 12 trials performed to assess forces of 4 different materials and 4 mounting systems

Kdf test results
KDF Test Results

  • Lighter materials reduce knockdown force

  • Test results similar to hand calculations

  • Hinge designs serve to attenuate knockdown

  • Vinyl and Polyurethane materials were too light for spring hinge and counterweight

Material conclusions
Material Conclusions

  • Vinyl and Polyurethane materials performed best but are not used

  • Materials cannot withstand turbulent airflow generated by mower

  • Single-ply curtain used on final design


Mounting conclusions
Mounting Conclusions

  • Existing fixed mount produced largest knockdown force

  • Counterweight ideal but not used for final design

    • More complex design

    • Requires more parts

    • Longer installation times

  • Implement conventional hinge design

Prototype design
Prototype Design

  • Add stuff here

Design validation
Design Validation

  • Compare prototype design to original system using:

    • Validation testing

    • Design metrics and target values:

      • Safety

      • Knockdown Force

      • Compatibility

      • Simplicity

      • Production Cost

Validation testing
Validation Testing

  • Curtain assembly performance test evaluates new design

  • Full scale validation test

  • Measured the force of 2” inward curtain deflection with mower on and off

  • Force measurements recorded for:

    • Hinged single-ply

    • Fixed single-ply

    • Fixed double-ply

Curtain assembly performance test results
Curtain Assembly Performance Test Results

  • Hinged single-ply yielded lowest force values

  • Confirm key findings of KDF test

  • Validates final design

Design metrics evaluation
Design Metrics Evaluation

  • New design uses material which passes ISO safety tests

  • Reduction in knockdown force by .4559 lbf

  • Compatible and simple design

  • Small increase in production cost per unit

Final design
Final Design?

  • Final design slightly modified to reduce manufacturing costs

Total project cost
Total Project Cost

*=not actually purchased by team

Path foward
Path Foward