The project's goal was the realisation of a dedicated experimental DOE, to evaluate the effect of tolerance variation in the gear efficiency.
Users of cylindrical gears in aeronautics demand continuous improvement such as increased power density, lightweight, compact size, reduced manufacturing costs, reduced noise, increased reliability and reduced operating costs.
From one point of view, causes of gear failure may include a design error, an application error, or a manufacturing error. Design errors include such factors as improper gear geometry, utilisation of the wrong materials, finishing quality levels, lubrication systems, or other specifications.
In this project the effect of variation of Pressure angle (α), Total cumulative pitch deviation (Fp), Total profile deviation (Fα) and Total helix deviation (Fβ) were analysed using a full factorial DOE to analyse 4 X’s variables at 2 levels, in order to study the following Y’s effects; Load capacity (contact pressure, root bending stress), Teeth wear (pitting, scoring/scuffing), Noise (transmission error) and Power losses.
With the support of Load Tooth Contact Analysis tools (LTCA) it was also possible to predict the transmission error graph with or without load and it is possible to display the grids of the bearing pattern and transmission error, with or without load, shaft angle, or run out to produce a map envelop of the expected behaviour of the gear set. Actual difficulty of these prediction tools was the lack of validation studies available. A specific numerical and experimental study was performed in order to analyse the effect of tooth profile optimization.
Both Airbus and Boeing have estimated around 30,000 new aircraft over the next 20 years, whose worth reaches 3.6 b$. Demand comes mainly from fast-growing markets in Asia, Middle East and Latin America but also the replacement of thousands of aircraft in more mature markets of Europe and North America.
In addition, 22,000 units of business jets are expected by 2033. This growth leads to a promotion of Business Regional Aviation in order to keep resource efficiency since 90% of travellers within Europe are able to complete their journey, door-to-door within 4 hours, statement declared by the European Commission.
In the next fifteen years commercial aircraft and business jets incorporated more than 140,000 engines with more than 575,000 million euros, representing more than 25 % of the volume estimated for the aeronautical sector market until 2030.
On one side future engines are based on new configurations to make them more efficient and more environmentally friendly. Strangely enough, these engines, contra-rotating open rotor ones (Rolls-Royce, Snecma) and Geared Turbofan ones (MTU, Pratt & Whitney), have incorporated an epicycloidal reducer as a key system. It also seems that Business Regional Aviation and jets will be based on turboprops whose key system is a planetary.
So these mechanical systems are set to play an even more important role in the future. In fact, engine manufacturers are already counting on companies like DMP to align them with this trend. On the other side a new global scenario is forcing component manufacturers like DMP to get more knowledge in order to give more added value. Very soon it could be difficult for European SMEs to compete in underprice strategies with developing countries manufacturers such as Brazil, Russia or China since offset contract model is imposed. Some OEMs are not willing to lose control of core technological culture and they have set suppliers development plans giving them a new and more important role. This implies that these SMEs must assume an adaptation for developing new capabilities such as designing and testing.
The OPTIMIZE project´s goal was the realisation of a dedicated DOE (Design of Experiments) to evaluate the effect of tolerance variation in the gear efficiency. Users of cylindrical gears in aeronautics demand continuous improvement such as increased power density, lightweight, compact size, reduced manufacturing costs, reduced noise, increased reliability and reduced operating costs.
The project has brought to light some relevant breakthroughs:
- The influence of mainly one design parameter (alpha) and one manufacturing tolerance (Fp) on the Gearbox performance.
- A DoE strategy in combination with adapted standard test rigs is feasible for these types of investigations.
- LTCA is coherent with experimental results.
- It is demonstrated that changes in microgeometry by using LTCA benefit gears performance.
With regard to the exploitation the Protection Right situation could have been an issue for DMP however this knowledge cannot be protected and it will remain within the company.
The potential customers are extremely demanding and some certifications will be asked: DOA (Design Organisation Approval), and POA (Production Organisation Approval). The aeronautics sector represents a huge opportunity. However a mayor threat is the fact that the market could not identify DMP as a reliable gear supplier as it still is a little unknown. Therefore specific dissemination action has been planned.
As business opportunities grows a business plan, including post-project financing plan, must be elaborated. Aeronautics is based on high-tech equipment acquisitions and the size of DMP is a weakness.
After the OPTIMIZE project TEKNIKER had broadened its gear testing capacity, in particular in the field of Tribology. This fact has positioned TEKNIKER as an experienced partner for solving tribological problems where wear, contact fatigue and efficiency studies could be carried out giving a stronger position in comparison to other competitor laboratories.