1.0.Summary

Basic Utility Vehicles (BUVs) are rugged, simple vehicles that can accommodate four passengers. They are designed for warm climates, slow speeds (under 25 mph), and rural, unpaved roads. BUVs provide mobility, freedom, and economic hope to people in rural areas of developing countries. They promote trade and sustainable development by enabling micro-business growth and trade at a grass-roots level.

For this project we are to design and build a working prototype of a BUV by May of 2000, at which time, our design and prototype will be entered in a national collegiate competition, sponsored by the Institute for Affordable Transportation[1].

Their mission statement is as follows:

By 2020, Basic Utility Vehicles (BUVs) will be facilitating trade and sustainable development in every developing country in the world. BUVs will be a key weapon in winning the war on poverty and enabling micro-business growth. These businesses will provide steady income, the dignity of work, and a means to escape poverty.

The winning design team will then go on to have their design used for mass production beginning in 2003.

2.0.Overview of Problem

In third world countries, the cost of transportation is exorbitant. The Institute for Affordable Transportation (IAT)1 is a non-profit organization dedicated to providing the world with transportation that is both affordable and reliable. As Engineers in the most prosperous country in the world, we feel it is our duty to share our expertise with the underprivileged peoples of the world. The problem identified by the IAT is that of transportation for the families and workers in the third world. Most families in this type of situation cannot afford the cost of a new automobile, and the older used cars available to them are extremely unreliable. Families depend on being able to get out of the rural environment to sell goods or services where there are needs for them. So, the issue then is to provide a means of transportation that will be reliable and affordable. The IAV is sponsoring a global competition to design and build a prototype of a basic utility vehicle.

3.0.Deliverables

  • Design and build a working prototype of a Basic Utility Vehicle that meets all of the specified design requirements.
  • Provide a full engineering report that includes failure analysis and performance data.
  • Provide CAD drawings and digital video clips of the vehicle to the public.
  • A complete financial analysis of the project including investment, and profit margins for production of 100k units per year.
  • A website that includes all of the above (except the vehicle) for judging by the Institute for Affordable Transportation

4.0.Requirements for the Competition

Categories of Competition

Clean Slate Design: design according to specification for a kit price of less than $900 (including material costs, kitting costs, and labor for sub-assemblies). This price does not include final assembly labor, overhead, freight, duties, and profit.

Modified Design: modify an existing chassis/suspension and meet specifications for a kit price of less than $1300 (i.e. chassis from a micro-car, electric vehicle, golf cart, motorcycle, go-kart, sand rail, ATV).

Design Requirements

  • The production vehicle cannot cost more than nine hundred dollars to build. The rest of the requirements for the competition are as follows
  • A modified design such as a power transfer unit must cost less than $1300.
  • Must carry a four-person load or 770 lbs.
  • The top speed should be 25 mph.
  • Must weigh less than 550 lbs.
  • Must have a ground clearance of at least 7.9 inches.
  • Minimum range of 120 miles.
  • Must have a turning diameter of less than 19.8 feet.
  • The engine should be an internal combustion engine. Two drive wheels are all that is required. The materials should be made from non-corrosive, water-resistant, UV resistant materials. The vehicle needs basic safety equipment such as seat belts, parking breaks, roll bar, head lights, and break lights. Ideally the weight distribution would be 65% to 35%.

5.0.Design Approach and Philosophy

For this project we will go through three different phases:

1)Solicitation of support

2)Design & Analysis

3)Production of prototype

When developing this vehicle, our BUV design team has some specific objectives in mind. The design should be focused on the end user. The vehicle will have features built into it that will enhance the quality of life for the operator. For example the parts and components will be designed so that they could be easily repairable. Most of the components should be made from generic steel stock so that the operator can repair it without a parts store. The size and volume of the vehicle are also concerns because of the distance these vehicles must be shipped. Failure modes and loads will also be a concern. The vehicle must be very rugged. The vehicle should also be made so that other manufacturers can copy it. The goal of this project is not to make a monopoly, but to help third world countries.

6.0.Phase 1: Solicitation Results

As a result from our first phase of this project (soliciting support), we have acquired stock steel from W.L Gore and C&D Mold. We have also obtained a vehicle from NAU’s Facilities Management. The vehicle is a 1981 Daihatsu Hijet Truck (See figure 1 &2). Its specifications are as follows:

  • Engine: 547cc, 2 cylinder gasoline (max speed 25 mph)
  • Wheelbase: 70.75 in
  • Bed: 72 in (length)
  • Ground clearance: 6 in

7.0.Phase 2: Design

Our original design approach was a clean slate design of a BUV, which was outlined in section 4. We had completed our initial design of the BUV during the fall 2000. This included frame dimensions, seating arrangement, engine placement and we also began looking at different suspension options.

When we acquired the Daihatsu, it was very surprising to see how closely it resembled our original design. This resulted in a design decision to change our design approach from a clean slate to a modified design approach.

Modified Design Approach

Consists of using the existing chassis (frame, suspension and drive-train) of the Daihatsu Hijet.

We have made the following modifications to resemble our vision of a BUV:

Modified bed- modifications will be made to accommodate two more passengers. This modification consists of adding a bench seat and a recessed region for leg room (See Figure to the right).
Roof Rack-a frame supporting a roof rack will be added to bed of the truck. It will hold a maximum load of 300 lbs (See Figure to the right).
It will require a significant amount of welding, and has been analyzed for its strength (see Analysis section 8). /
Modification Kit (above)
The BUV
This is our vision of a BUV. It accomadates seating for 4 passengers, it is small, light weight and has a load capacity of 1000 lbs. This vehicle can be used to transfer goods to a market place or as transportation to a work place. It meets requirments as outlined by the IAT (see requirments by the IAT) /
Daihatsu and our kit as a modified design

Specifications to date:

  • Engine: 547cc, 2 cylinder gasoline (max speed 25 mph)
  • Wheelbase: 70.75 in
  • Bed: 72 in (length)
  • Ground clearance: 6 in
  • Chassis design of the Daihatsu Hijet (see Figure 3)
  • Upper bed frame (see Figure 4 & 5)
  • Dimensions: 72inX40inX50in
  • Made from ASTM A-36 1.5 inch box steel or a mild steel 1020

8.0.Phase 2 continued: Analysis

Static Stability Analysis

To determine the stability of the Daihatsu, we calculated the center of gravity for the vehicle about the z-axis, when fully loaded. The angle about the y-axis is then determined when the vehicle loses stability.

It was calculated to be 29o, If at some point we determine this not to be acceptable we can make some simple modifications to improve this result.

i.e. we could lower the weight limit on the roof rack or lower the height of the rack itself.

Finite Element Analysis (FEA)

FEA is a method of analysis that breaks up complex geometry into small discrete pieces that can be analyzed easily. These pieces are then assembled mathematically in matrix form to represent, in this case, a solid. The overall stress is then calculated using the resulting matrix. FEA is a powerful method for computing stress (and other things) in complex geometries.

FEA model:
Type: Frame undergoing a large negative acceleration (such as a collision or a fast stop); Static nodal stress.
Load: 300 lbs on roof rack
Material: 1.5 inch box steel (assumed mild steel 1020), same as the frame material.Yield strength is 294.8 MPa
Case 1: frame with no gusset plate
Result: Stress of 350 Mpa
Factor of Safety <1...not good! /
Case 2: frame with gusset plate
Result: Stress of 180 Mpa,
Factor of Safety: 1.64...good! /
Gusset close-up 300 lb load
Moves stress concentration away from the weld to more predictable geometry /

9.0.Phase 3: Prototype

Bill of Materials:

Final Budget:

Note: Deserving of an award for most resourceful team!!!

As can be seen, the vehicle will easily accommodate four passengers as well as a full cargo load of 770 pounds.
Installation of the modified bed kit including roof cargo area, recessed section, and rear cargo area.
The implemented gusset plates on the upper frame. This shows how the plates were installed and welded on by use of a Lincoln MIG welder. Notice all the mating surface are welded.
This is a close-up of the recessed section of the bed. The bed was cut into three pieces, then the center piece was welded onto the frame using some structural steel. Also the jagged edges were covered with some sheet Aluminum.

10.0.Project Schedule

11.0.Conclusion

The challenge that faced the BUV Team this semester was to design a rugged, affordable vehicle for use by the peoples of the third world. The BUV design has gone through several design iterations to arrive at the current vision of this vehicle. Starting with a frame up design that accounts for cost, durability, and safety, the team was then presented with the opportunity to modify an existing vehicle. The ensuing design is a modification of a Daihatsu truck. The current design meets all of our requirements as well as those of the IAT.

This project has forced the BUV Team to think in terms of global, sociological context. The Team has had the opportunity to study and possibly impact the vast majority of the world’s population that does not have the comforts that we enjoy. As Engineers in the wealthiest nation in the world, it is our responsibility to consider those who are not as fortunate.

Recommendation for Production

Steps to estimate our cost per unit data:

1)Volume assumption of 100,000 units annually

2)Based on the Daihatsu Chassis and our modification kit

3)Start up costs will have to be estimated (training, site, materials, machinery)

4)We will propose that it be produced in Africa (close to test market Ghana & provides more economic opportunity for the locals)

5)We will propose that steel be purchased from Brazil (low cost due to their manufacturing processes)

6)Finally calculate the cost per unit<$1200

12.0.References

Institute for Affordable Transportation, Competition requirements and guidelines

Rapid Line, Performance suspension calculator; used for SOTA

Auto Fundamentals, an on-line introductory course to steering and suspension; used for SOTA

AutoZine Technical School, Information on suspension systems; used for SOTA

ANIMA, the Federation of the Italian Associations of Mechanical and Engineering Industries; used to locate the Italian manufacture, PIAGGO (Produces the Hijet)

MINIBUS Club, information on different vehicles including the Hijet

Embassy of Italy, page withinformation on different industries; used to help locate PIAGGO

PIAGGO, Manufacture of small vehicles; in search of Hijet information

Daihatsu, site with manufacture listings world wide; used in search of the Hijet manufacture

Appendix A

Design Drawings

Appendix B

Vehicle Documentation

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[1]Institute for Affordable Transportation, Competition requirements and guidelines