1.- Experimental mechanics
1.1- Application of the Methods of Experimental Stress Analysis
to complex Design Cases.
1.2- Determination of material answer to state of stress:
= static stress state through Fracture mechanics
Approach
= dynamic state of stress through Low Cycle and High Cycle
Fatigue Approach
2.- Engineering Design Methods
2.1- Analysis and application of QFD, FMEA, DOE tools to several
cases.
2.2- design and Construction of experimental Equipments for
mechanical tests, up to Special Testing Machines of
1300 and 2500 tons, (in collaboration with
other researchers of DIEM Department).
2.-Extended Information on Research Activity
First Researches
(Years 1974- 1990)
The research activity moved from the Experimental Stress
Analysis Engineering applications, with special attention to
optical methods like 2D and 3D Photoelasticity, that at that time
was the most powerful method for complex stress analysis.
Two areas of applied research in Mechanics, strictly related one
another, represent the interest of the Candidate: Stress Analysis,
when it is oriented towards the optimization and Mechanical Design
Strategies.
In previous years the Candidate oriented himself towards
problems of stress analysis of mechanical components of complicated
shape and loading distribution, /1/, /2/, /3/, /4/.
Some of these are related to:
1. -Stress analysis on nuclear and chemical pressures
vessels through photoelastic and strain gauges
methods.
A large experimental testing program was performed under several
contracts of Italian Nuclear Energy Authority (CNEN-ENEA) for
extensive investigations of nuclear pressure vessels, in order to
optimize the geometry of flanges /3/, nozzles, heads /5/, /6/, /7/,
/9/ with different loading condition such as pressure,
pretightening, internal and external loads. The 3-D photoelasticity
was extensively utilized on models obtained by casting in all-metal
mould. In order to generalize the results, they were compared with
result obtained from theoretical and numerical analysis and by
other authors for similar geometry /11/.
Some of the more important causes of errors were analyzed and,
where possible corrected. Poisson ratio effect e.g., was
theoretically investigated /8/ with reference to a cylinder-sphere
junction.
2. - Development of a method for the
derivation of acceptance levels for defects in turbomachinary
rotors based on a fracture mechanics approach.
In circumstances where it is necessary to examine the internal
quality of rotors in new or existing turbomachines by
non-destructive tests, it is also necessary to establish acceptance
levels for defects revealed. The developed analysis is dealing with
two aspects:
-
a detailed study of the interaction effects between two circular
cracks /21/ in order to define form and dimension of an "equivalent
crack and to validate an automatic analysis of the fatigue
propagation of defects /30/.
Through the use of photoelastic technique, stress intensity
factors KI and KII were determined,
An other special holographic technique /24/ was employed to
measure displacement field.
On the basis of all these investigations a theory for an
elliptical defect equivalent to two circular interacting coplanar
defects was proposed for a life prevision analysis of large
rotors.
An extensive characterization of a rotor steel was performed
/39/. Fracture toughness, static and fatigue parameters and the
environment influence were determined in different part of a rotor
.
Specimens from 5 mm to 150 mm were tested, and a complete
toughness-temperature curve was derived, Several testing machines
were developed by the Author and utilized:
Universal testing, machines of 100 KN, Special machines of 500
KN and 3000 KN, and Special small fatigue machines for
corrosion-fatigue, /l9/, /20/.
3. Effects of fabrication related stresses on product
performance .
Extensive experimental investigation was performed on mechanical
effects of fabrication stresses such as distorsion and stability
during subsequent manufacturing operations or service conditions.
After a review of the existing mechanical methods of stress
measurements, several industrial problems were studied and solved.
A complete internal stress history, during a fabrication process,
was reconstructed for case hardening steel shafts /32/.A strong
influence of the transformation of residual austenite was observed
during the last thermal treatment diagrams have been derived for an
optimized choice of the couple of value of temperature and time of
thermal relief.
4.-Life prevision and life extension analyses
4.1.- Shafts subjected to torsional fatigue loadings
The aim of this research is to verify the extension of the local
strain methods to the torsional loading condition and to collect
further fatigue data for materials utilized by turbomachinary
manufactures. These points have been investigated:
-Relationship between external loads and local strain and
stress
-Constitutive law (the cyclic stress-strain curve)
- Fatigue
behavior (fatigue curves)
For this reason several methods have been developed /37/
according to the following alternative assumptions: Neuber formula
and Direct numerical approach
The constitutive law determination needs tests in torsional
loading conditions.
It is an interesting finding that the cyclic shear stress-shear
strain relation derived from tests on solid specimens using Nadai
analysis, shows good agreement with that obtained more directly
from tests on thin walled tubes.
4.1. For a multiaxial state of stress the octahedral shear
strain is extensively used to correlate the cyclic stress-strain
curve. In /44/ is shown a very good agreement between the cyclic
stress-strain curve for torsion and push-pull conditions when the
octahedral shear strain is used to correlate the results.
Several theories have been suggested for failure criteria. In
the low-cycle fatigue regime it must be observed that, the
classical von Mises criterium differs if applied in terms of
maximum distorsion energy, maximum octahedral shear stress or
maximum octahedral shear strain. Only in the high cycle fatigue
regime these three criteria coincide and give identical results. At
the present state of research on the low-cycle fatigue under
multiaxial stress conditions is far from determining a possible
advantage of one the failure theories experimentally, because the
difference among equivalent strains is very small as compared to
the scatter of experimental data. The variations of the fatigue
strength ratio in torsion and push-pull provides a useful indicator
of the validity of the various criteria for different
materials.
Uniaxial push-pull strain controlled tests were performed on
solid circular specimens. The stress-strain curve was deduced
according to the Ramberg-Osgood model and the other described
model. Reversed torsional test were carried out using an axial
machine equipped by a special device which transforms the push-pull
movement in a pure torsional mode,
Solid and tubular specimens were utilized in order to obtain
shear stress-shear strain curves and fatigue curves.
In these tests an abrupt drop in twisting moment range, which
results from crack growth in the circumferential direction and/or
longitudinal direction of the specimen, was adopted as" failure".
/44/,/51/,/53/.
5.-Strategies in Design
(Years 1992- 2000)
Introduction
The candidate recognized as main field of interest that sum up
his experience of many years of application to the study of
technical system, on which he has tried to concentrate his effort
of educator and researcher.
Widespread recognition of the actual and potential adverse
effects of environmental degradation on socioeconomic development
has led to the introduction of Sustainable Development. The now
most common definition of sustainable development was introduced by
the World Commission on Environment and Development in 1987.
"Development that meets the needs of the present without
compromising the ability of future generations to meet their own
needs."
Engineers and designers play a limited, but significant, role in
Sustainable Development. They influence not only what is made but
also how things are made; consequently, we need to address the
issue of sustainable engineering systems..
From the point of view of Mechanical Design Sustainability is
developed according the following steps:
- Development of
a systematic Design approach, and Decision-based approach in order
to incorporate in the conceptual design phase all the requirements
of safety, ergonomy, technical performance, aesthetic contents and
environment protection.
5.1- Testing Machine of large capacity for Testing tubular
Products and Threaded Connections in Oil field
An original design of a new high capacity (1000 tons) testing
machine to evaluate performances of oilfield tubular products has
been developed /59/,, according to stringent test specifications
which must prevent in service failures. Failures of steel tubular
products are in fact currently costing the oil and gas industry
more than one-half billion dollars annually, and are expected to
worsen due to the harder environment.
5.2- Life extension evaluation of expansion joints with
dilatation bellows in pressurised water plants
Life extension of well functioning systems /72/ is a way to
reduce the impact to th environment. The technical problem is to
find enough confidence for tolerating a life exceeding the design
life. This result can be obtained on the basis of sound theoretical
and experimental analyses.
5.3 - Development of a line of robust
products
In robust design, a designer seeks to minimise the effects of
noise in the system without eliminating the causes. We treat
changes in the design variables as noise and the deviation function
(the performance of the system relative to the goals) as the signal
in robust design. We aspire to find regions of the design space
which are highly robust in this context by minimising the change in
deviation function over a corresponding change in the design
variables.
The design of experiment is a powerful tool for
evaluating the influence of a set of independent variables on a
Process performance, expressed by a dependent variables.
The Author has clarified that Experimentation and Testing.
are two different concepts:
- Experimentation must be performed in preliminary stages of the
process design in order to find the number and the values of the
independent variables that optimise the output.
- Testing, -- viceversa-- must be performed on prototypes to
evaluate the output of the process but does not suggest how to
modify the values of the control factors.
The Author has applied DOE concept in several cases. The most
attractive is the application of Design of
Experiment for fatigue life improvement of high stressed
vehicles components./73/ and /78/.
6.- Research Program in Progress (2000….) 6.1.-
Sustainability of a new development in the refrigerator systems.
Our objective is to focus research program primarily on how
systems can be designed to last a long time, provided they are
environmentally benign, to increase their sustainability.
From the point of view of the Mechanical Design, systems,
products and components can be seen as technical processes,
being their tasks the developing of a process, during their total
life cycle.
To do this, we concentrate on one aspect of design, namely,
reliability obtained through system robustness which plays an
important role in open engineering systems. We treat changes in the
design variables as noise and the deviation function (the
performance of the system relative to the goals) as the signal in
robust design.
In details the research is organised according to the following
steps;
Analysis of the production process on a product in order to
discover all the weak points of the process.
Analysis of the utilisation conditions of the product.
Validation of the method of risk assessment.
Critical points of the production process
Critical points in the utilisation process
A design of experiment will be introduced for some
experimentation in order to evaluate and to complete the knowledge
of the risk parameters
Redesign of the system on the basis of the information and
results obtained in the previous steps.
This research will have a international collaboration with
researchers of Wroclaw University in Poland .
6.2- Development of new design of sport devices
Design of new sport devices ( ski boots and ski) are an
attractive challenge to improve the quality of the human life. A
scientific approach can bring to new design of lighter more
effective ski boots and ski /80/ and /81/. Field tests represent
the key of evaluation and analysis of new solutions.
7.- Promotion of international relationships and
exchanges
The candidate is one of the Cofounder of Danubia Adria Committe
for Experimental Mechanics of Solids in the area of Central Europe
. This Committee, founded in 80' had the task to connect
researchers of Central Europe in the field of Experimental
Mechanics, organising regularly, an annual Symposium in the
following Countries ( Austria , Croatia , Czech Republic ,
Hungary , Italy , and Slovakia ). This Committee, for the wish of
the Candidate, was extended to Poland in 96 and later to
Romania . In 2002 the annual Symposium will be organised by polish
Collegues in Poland .
The DA has had a great role in keeping and establishing
scientific and human contacts between these Countries, favouring
common researches ( in Poland between Wroclaw University,
Bologna University in 1982, 1998, etc , through Prof. Bedzinski,
Dr. Cristofolini), between Warshaw University, Bologna University
(Prof. Stupinski, Dr. Pancewitz, ), in Czeck Republic (between a
Research Center in Prague and , Bologna University) and
common training Courses (see following paragraph).
8.- International Courses taught
Since 1994, named as organiser, coorganizer and teacher of
several Courses on Design for Quality, Biomechanics, Engineering
and Management, Engineering Design and Industrial Design
Interaction, in the Residential Centre of Bologna University in
Bertinoro (Forli), the Candidate has organized Courses in the
interest of several Countries, as Poland, Romania, Hungary, Czech
Republic, Slovakia, Baltic Republics, Ukraine etc. by the
Italian Ministry of Foreign Affairs.
A typical Course Format is the following:
1.- Total Quality Management :
- From ISO 9000 to TQM - New evaluation parameters- The new
indexes - Examples
2.- The Design Process
- Introduction to Concurrent Engineering Philosophy - Need of a
Systematic Design Procedure- The QFD- From Task to
Specification - The Conceptual design - The Embodiment
design - Failure analysis - A FMEA procedure
4.- Design of experiment:
- Introduction to the DOE Philosophy- Analysis of Variance-
Hypothesis testing- Power of a test- The interaction concept- The 2
level factorial and fractional factorial design- The Taguchi
method- The response surface method- Application of the DOE
to Design and to Process problems
5.- Statistical Process Control
- Histograms- Measures of variation- Statistical
inference- Pareto Analysis- Cause and Effect
Diagrams- Process Capability Indexes - Control Charts-
Case Study of Process Analysis
6.- Experimental approach to Mechanical Design-
Experimental shaping of Machine elements- Hints of Mechanics of
material- Application of experimental stress analysis techniques-
Strain gauges methods- Coherent optics methods
9.- Management activity
Since 1995 the candidate is President of the
Technical Committee 15 (TC15) of IMEKO, devoted to the development
of Measuremts in Experimental mechanics.
IMEKO is an international measurement Confederation of 32
Member Organisations individually concerned with the advancement of
measurement technology. Founded in 1958, the Confederation has
consultative status with UNESCO and UNIDO. The seat of the IMEKO
Secretariat is in Budapest, Hungary.
In 1999 he is Founder and Director of an High School at
Bologna University on Engineering Design and Industrial Design
Interaction, for a Master Degree in Design.
The idea of combining engineering education and art and
aesthetics education for better Designs is a tentative to overcome
the historical constraints of the two cultures, for a humanistic
approach to product design, that take into account the social
demand for a more conscious and sustainable development.
The course attempts to bridge the gap by providing the modern
engineer with at least a working knowledge of the fundamental of
quality technology.
Each lecture will be followed by workshop in which the
participants will be asked to work problems which related to the
lectures.
Main Topics are Drawing ( The aim of the course is to
help students to realise more personal goals in drawing. The
course offers a thorough introduction to a variety of drawing
materials, including charcoal, chalks, ink wash, brush and ink,
oil, pastel, collage and mixed-media).
Design Theories ( The course is devoted to the design for
function, and invention, which is the grandest form of design, in
both engineering and art. The relations between technology, form
and aesthetic are explored together with the way in which some of
our aesthetic preferences spring from the functional
requisites of design).
Quality planning and analysis (The course deals with the
quality needs of a modern society with requires an active role by
all major activities of engineering design. In the line of an
approach devoted to develop responsible attitudes towards the
importance of quality and reliability.)
Marketing ( The course discusses activities when the
product is made available to potential customer..New marketing
organisation have build their reputation upon some precise
methods).
CADCAM: from principles to practice ( . The purpose of
this course is to provide a tutorial for students who have interest
in the process of defining a product design with the aid of
computers and in developing manufacturing plans and in
planning and controlling operation of the manufacturing
systems).
Workshop activities ( CADCAM laboratory will be provided
for applications of reverse engineering and industrial
design. Every attendant can build freeform conceptual models. An
effective coordinate measurement technique is offered in order to
model the object. A compact 3D CNC machining centre is then
able to manufacture models. In this way in the CADCAM
laboratory it is possible carry on the complete cycle of reverse
engineering from a physical model or a sketch to functional
prototype.
