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The history of science and mechanics is confronted by two interconnected problems: a critical accumulation and systematization of historical information about the subject of study, and the relationship between events and the laws of their development.The influence of natural philosophy in classical times that led to the development of mechanics and engineering as a science from the 5th century B.C. to the Middle-Ages was investigated in a previous article by the author. The rapid development of mechanics as a science started in the 16th and the 17th century. Machine design as an applied science was heavily relying on mechanics. Since the beginning of the 19th century, mechanics became the theoretical basis of an increasing number of applied technical disciplines directly connected with the development of industry, the elaboration of new technological processes machines, and industrial plants. A brief history of the development of the theory of machines and mechanisms is attempted here, along with the personalities and Academic Institutions that influenced Mechanisms and Machine Theory from Medieval Times to the recent past.

Doureios Hippos or the Trojan Horse was the huge wooden structure, built by the Achaeans on Odysseus' suggestion, hiding a number of fully armed warriors inside, that eventually ended the ten year long siege of Troy (1194–1184 BC). The Greeks, pretending to depart and give up siege, left it before the city walls as an offering to the gods. The Trojan Horse was eventually moved inside the city walls, at night the hidden men emerged and opened the gates, thus permitting the Greek army to enter Troy and conquer it. From the references in the Iliad and vase paintings, archeological evidence concerning the Troy siege, and the Homeric shipbuilding, a reconstruction is attempted herewith. Analytical and numerical methods were incorporated to analyze the most conceivable loading situations of crucial structural elements of the reconstructed horse, load balancing, and transport kinematics and dynamics.

A new K-wire gripping configuration of the Ilizarov wire tensioning and hold assembly with an integrated load-cell is presented here. The method addresses two critical issues that appear in K-wire clamping assemblies in use, slippage and re-tensioning, being the major shortcomings of the standard fixation methods. The new grip can be re-tensioned by the patient, according to the load-cell measurements and the physician's instructions. The new design provides the advantages of a more accurate axial alignment of the K-wires, limited prestress loss, and lack of slippage. Detailed design with a commercially available solid modeling software and spread-sheet computation capability offers design flexibility for custom made solutions to adapt different patient's needs.

The intervention of a divinity in the action of a drama to resolve a conflict and, often, to bring the action to a conclusion was accomplished with ancient stagecraft, in which an actor playing the deity would be physically lowered by an elaborate piece of equipment into the stage area. This “god from the machine” was literally a Deus-Ex-Machina. Detailed information on stage scenery and machinery in the ancient theater are given by Vitruvius (1st Century BC) and Pollux (3rd Century AD). From the numerous references to such machines in extant tragedies or comedies and vase paintings, information about its design and operation is available, and efforts to reconstruct such mechanisms have been reported in the literature. Based on archeological evidence from the theater of Dionysus Eleuthereus in the western slope of the hill of the Acropolis, and previous reconstruction efforts, a new reconstruction attempt of the mechanism is presented. Analytical and numerical methods were incorporated to analyze the most conceivable loading situations of the different structural elements of the mechanism, as well as kinematics and dynamics, along with theater reconstruction.

Since ancient times upright stone slabs or pillars, the steles, bearing an inscription or design were serving as monuments or markers. Today, digital information and communications technologies produced a wide range of applications for collecting and processing historical data, and creating interactive information systems. This paper describes the design of a rotating info-stele providing on-screen visual and audio documentation for objects and monuments located through an integrated viewfinder. The info-stele is suitable either for indoor operation in museums or outdoors in archaeological sites. Initial design requirements incorporated the need for a smooth integration with sites of historical and cultural heritage, rotation according to a touch-screen signal, automatic positioning to pre-defined locations of interest, a silent two-speed operation mechanism for consecutive stops and all-the-way travel, user safety, and five or more language narrative options. The design objectives were followed by a detailed design procedure along with aesthetic considerations, user safety, strength and adverse environmental conditions resistance, vandalism proof design, and low maintenance. The proposed design is suitable for different applications as well as distant operation through the internet. The project was supported from the Greek Ministry of Culture.

Archimedes (ca. 287–212 BC) was born in Syracuse, in the Greek colony of Sicily. He studied mathematics probably at the Museum in Alexandria and made important contributions to the field of mathematics. Archimedes discovered fundamental theorems concerning the centre of gravity of plane geometric shapes and solids. He is the founder of statics and of hydrostatics. Archimedes was both a great engineer and a great inventor, his machines fascinated subsequent writers, and he earned the honorary title “father of experimental science”. Archimedes systematized the design of simple machines and the study of their functions and developed a rigorous theory of levers and the kinematics of the screw. His works contain a set of concrete principles upon which mechanics and engineering could be developed as a science using mathematics and reason.

Repeated loading of the outer strut leg of the Bjork–Shiley 60° convexo-concave (BSCC) valve results in fatigue crack propagation, with a duration from a few months to a few years. Sound and vibration analysis emitted from the strut of the BSCC valve due to impact is used to monitor the propagation of the fatigue crack before it would lead to the failure of one or both legs of the outlet strut. Analytical and experimental results established that the range of the fundamental natural frequency is 4000–8000 Hz. Analysis of sound emitted from the strut of the valve due to impact may be used to monitor the propagation of the fatigue crack before it would lead to the failure of the one or both legs of the outlet strut.

The development of transportation systems has significantly enhanced the welfare and modernization of society. Wooden vehicles pulled by animals have been used for land transportation since the early Bronze Age. Whole-body gharries with rigid wheels pulled by oxen appeared in Crete by 2000 BC or earlier. Horses originating from the East were depicted in early Cretan seal-rings of the same period. The two-wheeled horsedrawn chariot was one of the most important inventions in history. This vehicle provided humanity its first concept of personal transport and was the key technology of war for 2000 years. Chariots of Mycenaean and Archaic Greece with light and flexible four-spoked wheels acting as spring suspensions were depicted in vase paintings. The development of this vehicle incorporated the seeds of a primitive design activity and was important for engineering. The Trojan horse since 1194 BC and the helepolis since 700 BC were the first known machines on a wheeled base transported by horses or self-powered. Ancient engineers invented bearings lubricated with fat, and Romans introduced the ancestors of ball bearings for their wagons and carts. The historic evolution of wheeled transportation systems, along with early traction, suspension, and braking systems, is presented in this paper. Analytical and numerical methods are incorporated to analyze the most conceivable loading situations of typically reconstructed wheeled transportation systems in ancient times. Traction requirements both for horse-driven machines and the power for internal motors are also analyzed. This study can serve as a basis for further development of detailed reconstruction of transportation systems in antiquity.

The rollover stability of tank vehicles depends on a number of factors that result in a lateral shift of the centre of gravity, which influences roll dynamics in cornering. The most important factors are the height of the centre of gravity, the track width, the axle roll stiffness, suspension and tyre compliance, and suspension roll stiffness. A tilt table test and, alternatively, a calculation method are suggested for implementation by United Nations Economic Commission for Europe (UNECE) Regulation 111. In Greece, no available approved testing rig is available to carry out the required tests for the conformity of those vehicles with Regulation 111 and, consequently, the calculation method is almost exclusively adopted. However, the calculation method for Regulation 111 still remains a theoretical way to check the vehicle behaviour owing to the large number of non-validated physical parameters involved. Thus, there is a lack of reliability between results obtained by the calculation method from different inspection bodies for similar vehicles. A combined experimental and calculation method that determines the overall torsion-angular displacement relation for a vehicle on an inclined level under its own weight is discussed, and results of the application of this method in a large series of various types of road tanker are presented in this paper.

A linear full-car model with seven degrees of freedom was adopted for the simulation of the dynamic behavior of road tankers with a fixed tank. The vehicle is subject to selected typical road surface profiles and inertial loads due to acceleration, braking and driving on a curve. For the simulation, a Monte Carlo method is used for a sensitivity analysis of the suspension characteristics including tires and the road tanker’s CG vertical shift due to the liquid load in relation with the vehicles response to road profile. A standard deviation was assumed for the aforementioned vehicle design characteristics introduced for the simulations performed. The road tanker’s dynamic response was investigated and furthermore results were compared with a static model as proposed by UN-ECE Regulation R-111 for lateral stability. The proposed method can be used as a design tool for the prediction of road-tankers dynamic response and roll-over threshold from an early design stage.

The presence of a crack in a structural member introduces a local flexibility that affects its dynamic response. Moreover, the crack will open and close in time depending on the loading conditions and vibration amplitude. The changes in dynamic characteristics can be measured and lead to an identification of the structural changes which eventually might lead to the detection of a structural flaw. The results of various independent evaluations of changes in the natural frequency of vibrations of cracked structural elements are reported. A crack model of a continuous flexibility, found with fracture mechanics methods using the displacement field in the vicinity of the crack developed recently is used here. The analytical results for the cracked elements behaviour based on the continuous crack flexibility vibration theory were correlated with numerical solutions, the lumped-crack beam vibration analysis and experimental results obtained on aluminium and steel beams with open cracks.

This memorial tribute to the late Professor Andrew D. Dimarogonas is in two parts. The first part is a brief account of his life and his professional career and achievements. The second part is a bibliography of his publications.

A continuous cracked beam vibration theory is used for the prediction of changes in transverse vibration of a simply supported beam with a breathing crack. The equation of motion and the boundary conditions of the cracked beam considered as a one-dimensional continuum were used. The eigenfrequency changes due to a breathing edge-crack are shown to depend on the bi-linear character of the system. The associated linear problems are solved over their respective domains of definition and the solutions are matched through the initial conditions. The changes in vibration frequencies for a fatigue-breathing crack are smaller than the ones caused by open cracks. The method has been tested for the evaluation of the lowest natural frequency of lateral vibration for beams with a single-edge breathing crack. Experimental results from aluminium beams with fatigue cracks are used for comparison with the analytical results.

The dynamics of a cracked fixed-free bar with a breathing crack in longitudinal vibration is investigated. The Hu–Washizu–Barr variational formulation was used to develop the equation of motion and the boundary conditions of the cracked bar as a one-dimensional continuum. The crack was modelled as a continuous flexibility using the displacement field in the vicinity of the crack found with fracture mechanics methods. The eigenfrequency changes due to a single open-edge breathing crack, are shown to depend on the bilinear character of the system. The associated linear problems are solved over their respective domain of definition and then the solutions are matched through the initial conditions. These changes are smaller than the ones caused by open cracks. The method has been tested for different bar configurations corresponding to crack location, crack depths, cross-section dimensions, and Poisson’s ratio. The natural frequencies obtained from this model agree well with experimental results.

A continuous cracked bar vibration theory is developed for longitudinal vibration of rods with an edge crack. The Hu–Washizu–Barr variational formulation was used to develop the differential equation and the boundary conditions of the cracked bar as a one-dimensional continuum. The crack was modelled as a continuous flexibility using the displacement field in the vicinity of the crack found with fracture mechanics methods. The results of three independent evaluations of the lowest natural frequency of longitudinal vibrations of a bar with a single edge crack are presented: the continuous cracked bar vibration theory, the lumped crack bar vibration analysis, and experimental results obtained on aluminum bars with fatigue cracks. Experimental results fall between the values predicted by the two analytical methods. Moreover, the continuous bar theory agrees better with the experimental results than the lumped crack flexibility theory for small cracks. For larger cracks, a / h >0.4, experimentation was difficult due to the co-existence of several coupled modes and no reliable results could be obtained.

A continuous cracked beam vibration theory is developed for the lateral vibration of cracked Euler–Bernoulli beams with single-edge or double-edge open cracks. The Hu–Washizu–Barr variational formulation was used to develop the differential equation and the boundary conditions of the cracked beam as a one-dimensional continuum. The displacement field about the crack was used to modify the stress and displacement field throughout the bar. The crack was modelled as a continuous flexibility using the displacement field in the vicinity of the crack, found with fracture mechanics methods. The results of two independent evaluations of the lowest natural frequency of lateral vibrations for beams with a single-edge crack are presented: the continuous cracked beam vibration theory developed here, and a lumped cracked beam vibration analysis. Experimental results from aluminum beams with fatigue cracks are very close to the values predicted. A steel beam with a double-edge crack was also investigated with the above mentioned methods, and results compared well with existing experimental data.

A continuous cracked bar vibration model is developed for the lateral vibration of a cracked Euler-Bernoulli cantilevered beam with an edge crack. The Hu-Washizu-Barr variational formulation was used to develop the differential equation and the boundary conditions for the cracked beam as an one-dimensional continuum. The crack was modelled as a continuous flexibility using the displacement field in the vicinity of the crack found with fracture mechanics methods. The results of three independent evaluations of the lowest natural frequency of lateral vibrations of an aluminum cantilever beam with a single-edge crack are presented: the continuous cracked beam vibration model, the lumped crack model vibration analysis, and experimental results. Experimental results fall very close to the values predicted by the continuous crack formulation. Moreover, the continuous cracked beam theory agrees better with the experimental results than the lumped crack flexibility theory.

A consistent continuous cracked bar vibration theory is developed. The stress and displacement field about the crack was used to modify the stress and displacement field throughout the bar, and reduction to one spatial dimension was achieved by integrating the stress and displacement fields throughout the bar cross-sections so that the total displacement would be exact. The resulting linear differential equation with variable coefficients has the modified displacement field due to the crack imbedded in it. Any number of cracks can be introduced into the differential equation as modifications of the displacement field. A numerical solution and a first order perturbation solution are presented for the prediction of changes in longitudinal vibration natural frequencies of a fixed-free bar with a single open-edge transverse crack. To assess the validity of the assumptions made experiments on aluminium bars with fatigue cracks were performed. The analytical results correlate very closely with experimental results with better correlation than the local flexibility solution.

The question of crack detection from dynamic measurements is further extended and discussed in Chap. 7. A general stiffness matrix for cracked structural members is introduced, to model the respective dynamic system. This stiffness matrix can be further utilized for static, dynamic or stability analysis of a structure with cracked members of rectangular or circular cross-section. Off-diagonal terms indicate vibration coupling. The change in dynamic response is analytically evaluated for simple systems and by means of approximate methods for more complicated ones. The outlined procedure can be used for engineering analysis in two ways: (a) as a design tool, to assist in structural optimization with the objective of achieving certain specific dynamic characteristics; and (b) as a maintenance and inspection tool, to identify structural flaws, such as cracks, by linking the variations in service of the structure's natural frequencies to structural changes due to the cracks.

The problem of cracked rotor dynamics is discussed in Chap. 6. Analytical formulation for crack local flexibility in relation to crack depth yields a supervisory instrument which can give an early crack warning. Fracture mechanics methods provide stress intensity factors for the investigation of rotor’s dynamic performance for varying crack depth. Open cracks lead to linear systems, while closing cracks lead to non-linear ones. Analytical solutions are obtained, which can be used to monitor crack propagation or to identify cracks in service.

A tapered spring friction clamping assembly replaced the bolted grip and hold assembly of the Ilizarov wire tensioning device. An integrated force transducer records the wire tension and according to the physician’s instructions the patient adjusts himself the K-wire tension. Analytical solutions of the K-wires axial stress in relation with transverse loading provide the basis for the design of different gripping configurations to adapt different applications needs regarding K-wire length and diameter, varying tension force requirements, and different force transducers configurations. The proposed method provides design flexibility, and operational validation of this new Ilizarov fixator.

Greece, via its PRODEX membership intends to meaningfully participate to the instrument development of a flagship ESA mission, the Solar Orbiter (SolO). This involvement pertains to hardware development for SolO's Spectrometer/Telescope for Imaging X-rays (STIX), namely, STIX's movable attenuator. SolO will allow close-up and high-latitude studies of our mother star, the Sun, based mostly on remote-sensing measurements (imaging). STIX is a critical SolO instrument, enabling one of its major science goals: understanding and acceleration of electrons at the Sun and their transport into interplanetary space. The attenuator, or shutter, that will be developed by the Greek team, is a critical component of the STIX instrument. Attenuators are dictated by the substantial dynamical range of incident X-ray fluxes from solar flares: the largest X-ray flares can give as many as 105 more count rates in X-ray photons compared to those of the smallest microflare that STIX can detect. lt is proposed that two mechanisms are developed for a comparative study. First, a mechanism based on sensitive Shape Memory Alloy actuators and, second, one based on a piezoelectric actuator module. Both mechanisms will be designed and manufactured and then tested in vacuum and alternating high-low temperature conditions. Evaluation of reliability and accuracy in assembly and operation will follow. A vibrating table will be used for the dynamical analysis of the mechanism and independent strength tests of the various parts of the mechanism will follow.

Archimedes (ca. 287–212 BC) was born in Syracuse, in the Greek colony of Sicily. He studied mathematics probably at the Museum in Alexandria. Archimedes made important contributions to the field of mathematics. Archimedes discovered fundamental theorems concerning the center of gravity of plane geometric shapes and solids. He is the founder of statics and of hydrostatics. Archimedes was both a great engineer and a great inventor, his machines fascinated subsequent writers, and he earned the honorary title “father of experimental science”. Archimedes systematized the design of simple machines and the study of their functions and developed a rigorous theory of levers and the kinematics of the screw. His works contain a set of concrete principles upon which mechanics could be developed as a science using mathematics and reason. His contribution separates engineering science from technology and crafts, often confused for matters arrived at empirically through a process of long evolution. His works have influenced science and engineering from the Byzantine period to the Industrial Revolution and the New Era.

In some ancient Greek drama plays, the stage machine used to bring the gods or the heroes of the tragedy on stage, known with the Latin term deus-ex-machina, was used for the solution of an apparently insoluble crisis. A twin-facing stone base was found in the theater of Phlius in Corinthia, Greece, behind the stage building. The existence of similar foundations in other ancient theaters indicates their use for specific purposes connected with the needs of the play. An attempt to reconstruct the mechanism is presented based on archeological evidence and literary descriptions. The reconstructed mechanism was designed for path generation and comprised a single beam with ropes controlling its planar motion and a sidle twin lifting system. DOI: 10.1115/1.4000530

Developments in natural philosophy and the scientific method in the 6th and 5th Centuries BCled to rapid development of engineering design in the 4th to 1st Centuries BCin the Greek and Hellenistic world, reaching maturity in the Roman Empire after the 2nd Century ADwhen Greek mathematical works started being translated into Latin. Design rules and concepts were practiced extensively by the engineers of ancient times leading to machine design from machine elements to the design of a machine as a system. Purely mechanical treatises on machinery go back to the 4th century BC.For the solution of mechanical problems and the design of equipment many basic scientific principles had to be explained at this time, and also trial and experimentation was established. The process of engineering design evolution from the 4th century BCup to modern era is discussed here.

The stage machine used to bring the gods or the heroes of the tragedy on stage, known with the Latin term Deus ex machina was used in some ancient Greek drama, for the solution of an apparently insoluble crisis. This intervention of a god or a hero brought on stage was possible by this elaborate piece of equipment, the mechane. Archaeological evidence in the ancient Greek theatre of Phlius (Corinthia) was reappraised in an attempt to reconstruct the mechane.

Ten thousand domestic hot water solar systems were surveyed in Greece to assess component and system reliability. Data concerning the functioning condition of the systems was collected, a computerized data base was established and statistical analysis was performed. This work is part of a solar system evaluation program within the European Community. Greece was selected due to the high concentration of solar collector systems and the fact that these systems have reached maturity, the average lifespan being five years.

In some ancient Greek drama, an apparently insoluble crisis was solved by the intervention of a god often brought on stage by an elaborate piece of equipment. This “god from the machine” was literally a Deus Ex Machina. Archaeological evidences and descriptions of mechanisms used in the ancient Greek theatre were investigated in an attempt to reconstruct the Deus Ex Machina. None of these machines, made of perishable materials is extant. However, from the numerous references to such machines in extant tragedies or comedies and vase paintings, information about its design and operation is available. Static and dynamic analysis and simulation of the mechanism kinematics were performed. The reconstructed mechanism is a spatial three or four bar linkage designed for path generation.

Archimedes (ca. 287–212 BC) was born in Syracuse, in the Greek colony of Sicily. He studied mathematics at the Museum in Alexandria. Archimedes systematized the design of simple machines and the study of their functions. He was probably the inventor of the compound pulley and developed a rigorous theory of levers and the kinematics of the screw. He is the founder of statics and of hydrostatics, and his machine designs fascinated subsequent writers. Archimedes was both a great engineer and a great inventor, but his books concentrated on applied mathematics and mechanics and rigorous mathematical proofs. Archimedes was also known as an outstanding astronomer; his observations of solstices were used by other astronomers of the era.

The objective of this work is to develop a fault diagnostic system of an electric car based on artificial neural networks (ANN). Data from an on-board data acquisition system capable of measuring a number of parameters during the electric car operation are used to train an artificial neural network. The car’s monitoring system using the computational power of modern portable personal computers, user-friendly data input and output, and fullscreen editor capabilities is used for fault diagnosis. The ANN was trained to predict the temperature of the two motors of the electric car in order to detect any fault. The training data were learned by the ANN with an excellent accuracy. The results obtained for the training set are such that they yield coefficients of multiple determination (R2-values) equal to 0.9912 and 0.9939 corresponding to the values of the temperatures of the two motors respectively. Completely unknown data were then used for validation of the network. The correlation coefficients obtained in this case were equal to 0.954 and 0.987 for the temperature of the two motors respectively, which are very satisfactory. The fault diagnostic system developed compares the measured and predicted temperatures from the two motors and gives an “error” when a difference greater than a user defined tolerance is obtained. A polling routine was developed which sums-up the error signals and only gives a “fault” when 10 consecutive error reading are recorded. In this way false error conditions, which might arise from erroneous data recorded from the thermocouples and/or from wrong predictions of the network, are avoided

On June 26 2006, a 55-passenger motorcoach, operated by a local food-industry and carrying 14 passengers, was travelling on the two-lane national road EO-90 Chania-Iraklion westbound, in the island of Creta, Greece. The same day, a road tanker consisting of a two-axle tractor and a three-axle semitrailer aluminium tanker, loaded with JETA1 fuel was travelling westbound on the same national road. As the bus approached milepost 64.7 km, it slowed down to the right side of the highway until a secondary stop, for a passenger to depart, and while restarting the oncoming road tanker collided at the bus back. Three passengers and the truck driver were killed, and six passengers received serious injuries. The accident investigation and reconstruction in accordance with the application of the European Agreement Concerning the International Carriage of Dangerous Goods by Road (ADR), and the criteria which could be adopted to judge risk acceptability, are discussed.

The problem of the influence of a crack in a welded joint on the dynamic behaviour of a structural member is discussed in this work. Analytical and experimental investigation gave the relation between the change in natural frequency of vibration of a cantilever beam and the crack depth that appears at the built-in edge which is clamped by way of a weld. Measurement of the change of the natural frequency of the beam thus can give information for crack appearance and furthermore make possible the estimation of its depth. The results have been used to determine the behaviour of beams with different boundary conditions and can be extended to formed structures with complicated geometries.

Cracks that develop on machine members and structures influence their dynamic behavior. The Rayleigh principle is used for an estimation of the change in the natural frequencies and modes of vibation of the structure if the crack geometry is known, assuming that the eigenvalue problem for the uncracked structure has been solved in advance. The method reduces the computational effort needed for the full eigensolution of cracked structures and gives acceptable accuracy. It can be extended to higher modes and to decompose degenerate modes found in symmetric structures. To demonstrate the change in the dynamic behavior of linear structures with the crack depth, a cylindrical shaft and a plane frame consisting of prismatic bars were analyzed for dynamic sensitivity to surface cracks.