The theme of this diploma thesis is design of skid steer loader with capacity up to 1 tonne. The result of this thesis is a conceptual solution of loader. It describes structural, technological, ergonomic and visual aspects with respect to current trends.

Skidding contributes to up to 35% of wet pavement accidents. Pavement surface friction therefore is an important component of highway safety. The skid resistance also varies seasonally and reduces over time due to surface polishing. These leave the pavement in a state of increased risk of skidding accidents. An adequate surface friction that accommodates the seasonal and long term variations is essential for safety over the pavement surface service life. The resistance to skidding, however, depends on surface microtexture and macrotexture. Alternatively, increased texture aimed at increased and durable surface friction may affect the noise generated on the road. In fact, traffic noise is a growing problem throughout the world. Noise barriers, traditionally used for noise reduction, are expensive and inefficient in some cases. As the pavement surface characteristics play a key role in noise generation and propagation, it provides a window for noise reduction by altering the pavement surface. The challenge, however, is to provide a smooth, quiet, long-lasting, and economic pavement with adequate and durable surface friction. This research has been directed to address this challenge and to provide a realistic guideline. The tire-pavement noise, sound absorption, and skid resistance performances of various flexible and rigid pavement surfaces have been examined using the field and laboratory test data. Models for the prediction of pavement skid resistance including the seasonal and long term variations have also been developed correlating the influencing factors. A value engineering approach has been proposed to accommodate the construction and maintenance costs, longevity, smoothness, safety and noise in the selection of pavement surfaces.

Skidding contributes to up to 35% of wet pavement accidents. Pavement surface friction therefore is an important component of highway safety. The skid resistance also varies seasonally and reduces over time due to surface polishing. These leave the pavement in a state of increased risk of skidding accidents. An adequate surface friction that accommodates the seasonal and long term variations is essential for safety over the pavement surface service life. The resistance to skidding, however, depends on surface microtexture and macrotexture. Alternatively, increased texture aimed at increased and durable surface friction may affect the noise generated on the road. In fact, traffic noise is a growing problem throughout the world. Noise barriers, traditionally used for noise reduction, are expensive and inefficient in some cases. As the pavement surface characteristics play a key role in noise generation and propagation, it provides a window for noise reduction by altering the pavement surface. The challenge, however, is to provide a smooth, quiet, long-lasting, and economic pavement with adequate and durable surface friction. This research has been directed to address this challenge and to provide a realistic guideline. The tire-pavement noise, sound absorption, and skid resistance performances of various flexible and rigid pavement surfaces have been examined using the field and laboratory test data. Models for the prediction of pavement skid resistance including the seasonal and long term variations have also been developed correlating the influencing factors. A value engineering approach has been proposed to accommodate the construction and maintenance costs, longevity, smoothness, safety and noise in the selection of pavement surfaces.

The problem of providing adequate wet-road skid resistance on urban roads has received relatively little attention from highway maintenance authorities. This study is an assessment of the potential for reducing accident rates by improving skid resistance levels on such roads. Reasons for the neglect of urban skid resistance are discussed and an assessment made of the scale of the skidding problem in this context. Evidence is presented to demonstrate that the potential for accident reduction is greater than is indicated by the statistics for reported skidding accidents. The pattern of frictional demand and the measurement of skid resistance are discussed, as are the technical difficulties associated with maintaining good skid resistance on heavily-trafficked roads. The performance of conventional surfacing materials is assessed and recently-developed materials are evaluated. It is suggested that the attainment of high skid resistance is inhibited by economic rather than technical factors. Nationally-proposed standards for skid resistance are examined and modifications are suggested for urban use. The problem of defining accident risk at an individual site is examined and the relationship between accident rate and skid resistance investigated using regression techniques with data from the Greater London area. Criteria are developed for identifying sites where an improvement in skid resistance is likely to be effective in reducing accidents and consideration is given to the economic justification for skid resistance improvements. Alternative strategies are considered and a policy is proposed which would be practicable and cost-effective and, it is argued, could lead to a substantial reduction in accident rates.

Aggregate properties influence different aspects of asphalt pavement performance. Aggregate polishing characteristics are directly related to pavement surface frictional properties and thus to skid resistance. Aggregate resistance to degradation (abrasion and breakage) is another important property that influences pavement performance. Aggregate degradation could take place during production due to plant operations and during compaction, leading to change in aggregate characteristics and mix properties. In addition, aggregate resistance to degradation is important in mixes such as Stone Matrix Asphalt (SMA) and Open Graded Friction Course (OGFC) that rely on stone-to-stone contacts among coarse aggregates. Some aggregates in these mixes fracture due to the high stresses at contact points. Many test methods exist for measuring aggregate polishing and degradation, but a critical review of these methods reveals that they suffer from being time consuming, are unable to differentiate between aggregates with distinct resistance to polishing, or unable to differentiate between aggregate resistance to abrasion and breakage. New methodologies are needed to give better assessment of aggregate resistance to polishing, abrasion, and breakage. The thesis presents the development of new methods for measuring aggregate resistance to polishing, abrasion, and breakage. These methods rely on measurements using the Aggregate Imaging System (AIMS) and Micro-Deval. The new method for measuring aggregate resistance to polishing monitors change in aggregate texture as a function of polishing time. As such, it provides the initial texture, rate of polishing, and final texture. The new method for measuring aggregate degradation is capable of distinguishing between breakage and abrasion. In this method, abrasion is defined as the reduction in aggregate angularity, while breakage is defined by fracture of particles. The new methods are shown to be rapid and accurate, and they require reasonable training. Since both AIMS and Micro-Deval are used in the new methods, it was necessary to evaluate the repeatability of these two methods. Measurements using two AIMS units and two Micro-Deval machines were used to assess the variability. There was no statistical difference between the measurements of the two AIMS units or between the measurements of the two Micro-Deval units.

Aggregate properties influence different aspects of asphalt pavement performance. Aggregate polishing characteristics are directly related to pavement surface frictional properties and thus to skid resistance. Aggregate resistance to degradation (abrasion and breakage) is another important property that influences pavement performance. Aggregate degradation could take place during production due to plant operations and during compaction, leading to change in aggregate characteristics and mix properties. In addition, aggregate resistance to degradation is important in mixes such as Stone Matrix Asphalt (SMA) and Open Graded Friction Course (OGFC) that rely on stone-to-stone contacts among coarse aggregates. Some aggregates in these mixes fracture due to the high stresses at contact points. Many test methods exist for measuring aggregate polishing and degradation, but a critical review of these methods reveals that they suffer from being time consuming, are unable to differentiate between aggregates with distinct resistance to polishing, or unable to differentiate between aggregate resistance to abrasion and breakage. New methodologies are needed to give better assessment of aggregate resistance to polishing, abrasion, and breakage. The thesis presents the development of new methods for measuring aggregate resistance to polishing, abrasion, and breakage. These methods rely on measurements using the Aggregate Imaging System (AIMS) and Micro-Deval. The new method for measuring aggregate resistance to polishing monitors change in aggregate texture as a function of polishing time. As such, it provides the initial texture, rate of polishing, and final texture. The new method for measuring aggregate degradation is capable of distinguishing between breakage and abrasion. In this method, abrasion is defined as the reduction in aggregate angularity, while breakage is defined by fracture of particles. The new methods are shown to be rapid and accurate, and they require reasonable training. Since both AIMS and Micro-Deval are used in the new methods, it was necessary to evaluate the repeatability of these two methods. Measurements using two AIMS units and two Micro-Deval machines were used to assess the variability. There was no statistical difference between the measurements of the two AIMS units or between the measurements of the two Micro-Deval units.

Manufactured fine aggregates are a product created when rocks are crushed using a mechanical crusher. With the depletion of sources of natural sands, the usage of manufactured fine aggregates has increased. Manufactured fine aggregates have properties that differ from natural sands; for this reason, the plastic and hardened properties of concrete produced using manufactured fine aggregates differ from the properties of concrete made with natural sands. The main concrete properties affected by the usage of manufactured fine aggregates are skid resistance, workability, and finishability. The aim of this research project was to investigate how manufactured fine aggregates could be used in concrete pavements without causing workability or skid related issues. To improve the workability of concrete made with manufactured fine aggregates, the use of the optimized mixture proportioning method developed by the International Center for Aggregate Research (ICAR) was investigated. Results obtained from this testing were used to make recommendations on how the ICAR method for pavement concrete could be improved The goal of this research was to also develop laboratory tests that could reasonably predict skid performance of concrete pavements made with different types of sand. For this purpose concrete slabs made with different sands were evaluated for friction and texture using a circular texture meter (CTM), a dynamic friction tester (DFT), and a polisher. To ensure that the values obtained at the laboratory related to field performance, test sections constructed with 100% limestone sand and blended sands were evaluated. Laboratory and field test results for skid were used to identify aggregate tests that best correlates with concrete performance. Results show that the micro-Deval test for fine aggregates could be used to predict the polish resistance of concrete laboratory specimen. Results from field testing has shown that if limestone fine aggregates are not blended with siliceous sands, PCC pavements made with limestone sands on truck lanes could experience a large drop in skid resistance within a year of service. Results obtained from laboratory testing showed that blending a small quantity of siliceous sand with limestone sands considerably increased the skid resistance of concrete specimens. / text

A composite skid landing gear design investigation has been conducted. Limit Drop Test as per Federal Aviation Regulations (FAR) Part 27.725 and Crash test as per MIL STD 1290A (AV) were simulated using ABAQUS to evaluate performance of multiple composite fiber-matrix systems. Load factor developed during multiple landing scenarios and energy dissipated during crash were computed. Strength and stiffness based constraints were imposed. Tsai-Wu and LaRC04 physics based failure criteria were used for limit loads. Hashin s damage initiation criteria with Davila-Camanho s energy based damage evolution law were used for crash. Initial results indicate that an all single-composite skid landing gear may not be feasible due to strength concerns in the cross member bends. Hybridization of multiple composites with elasto-plastic aluminum 7075 showed proof of strength under limit loads. Laminate tailoring for load factor optimization under limit loads was done by parameterization of a single variable fiber orientation angle for multiple laminate families. Tsai-Wu failure criterion was used to impose strength constraints. A quasi-isotropic N = 4 (pi/4) 48 ply IM7/8552 laminate was shown to be the optimal solution with a load factor under level landing condition equaling 4.17g s. LaRC04 predicts that failures will be initiated as matrix cracking under compression and fiber kinking under in-plane shear and longitudinal compression. All failures under limit loads being reported in the metal-composite hybrid joint, the joint was simulated by adhesive bonding and filament winding, separately. Simply adhesive bonding the metal and composite regions does not meet strength requirements. Filament wound bolted metal-composite joint shows proof of strength. Filament wound composite bolted to metal cross member radii is the final joining methodology. Finally, crash analysis was conducted as per requirements from MIL STD 1290A (AV). Crash at 42 ft/sec with 1 design gross weight (DGW) lift was simulated using ABAQUS. Plastic and friction energy dissipation in the reference aluminum skid landing gear were compared with plastic, friction and damage energy dissipation in the hybrid metal-composite design. Damage in composites was modeled as progressive damage with Hashin s damage initiation criteria and Davila-Camanho s energy based damage evolution law. The latter meets requirements of aircraft kinetic energy dissipation up to 20 ft/sec (67.6 kJ) as per MIL STD 1290A (AV). Weight saving possibility of up to 49% over conventional metal skid landing gear is reported. The final design recommended includes Ke49/PEEK skids, 48 ply IM7/8552 cross member tapered beams and, Al 7075 cross member bend radii bolted to the filament wound composite tapered beam. Concerns in composite skid landing gear designs, testing requirements and future opportunities are addressed.

It has been well proven that as the skid resistance of a road surfacing decreases, the number of loss of control type crashes increases, causing road death and injuries. However, the management of skid resistance of road surfacings continues to be difficult due to the inherent and sometimes random variation in skid resistance levels over time. This study is an investigation and analysis of seasonal and short term variation of measured skid resistance in two phases. Phase 1: Regular field monitoring was undertaken using the GripTester and the Dynamic Friction Tester measurement devices on seven sites in the Auckland and Northland Regions of New Zealand was undertaken over a three year period. The effects of temperature, rainfall, contaminants, new surfacings, geometric elements and aggregate properties were analysed to investigate factors that initiate changes in the measured skid resistance of pavement surfacings. Phase 2: Laboratory prepared samples were constructed for accelerated polishing and skid resistance testing of four different aggregates (two greywackes, a basalt and an artificial iron-making melter slag aggregate). The samples were polished in an accelerated polishing machine to an ‘equilibrium skid resistance’ level (Stage 1 polishing). Contaminants were then added to the accelerated polishing process to determine the effect of varying additive, particle size and hardness in an attempt to simulate seasonal and/or short-term variations that occur in the field. The results have demonstrated that significant and previously unpredictable variations (greater than 30%) in measured skid resistance can occur over short time periods. These variations cannot be explained by any one factor. They are the result of a number of inter-related factors, including the geological properties of the aggregates and the contaminants themselves, the previous rainfall history, the road geometry, the calendar month of the year and (depending upon the measurement device), the temperature during testing. The laboratory tests demonstrate that accelerated polishing tests of aggregate samples could be prepared for testing by the Dynamic Friction Tester and that significant variations in measured skid resistance could be simulated on various aggregates in the laboratory by the addition of contaminants. The results of the testing and addition of contaminants on various aggregates resulted in significant behavioural differences which were related to the geological properties of the aggregates themselves, as well as the contaminants used in the accelerated polishing process. The findings of the research have specific relevance to three areas of industry; Road Controlling Authorities who are primarily interested in skid resistance policy, standards and management, Road Asset Managers who operate, maintain and manage condition level and the safety aspects of the road network and Crash Investigators who collect and analyse crash data primarily for legal proceedings. All three of these industry organisations need to clearly understand the inherent variability of skid resistance, the factors involved and the effects that geological and environmental variations have on skid resistance measurement. / Specific appreciation (as outlined below) is given to the significant industry partners/supporters that have helped support the research in many different ways. Firstly, I must give special thanks to Works Infrastructure Limited who have supported the research both financially and with resources almost from the outset of the research programme. The field testing data collection in the Northland Region of New Zealand would not have been possible without the support of the Whangarei Works Infrastructure team which included Peter Houba, Peter King, Matthew Findlay, Glen Kirk and the temporary traffic control team headed by Derek Phillips. Thanks also go to the Auckland Works Infrastructure testing laboratory which supplied aggregate supplies for laboratory sampling and testing and whose technicians also undertook Polished Stone Value tests on the aggregate samples. Special thanks are also given to Michael Haydon and David Hutchison from the technical management team of Works Infrastructure who have always been willing to listen to my requests and the many discussions that we have had on aspects of skid resistance, policy and technical matters. Pavement Management Services and especially Dr John Yeaman and Daniel Rich for their support for the research programme from the beginning, and secondly for financially contributing to the purchase of the Dynamic Friction Tester for the static field testing and the laboratory tests. Achnowledgement is also given to The Ports of Auckland and especially Jo Campbell of the AXIS Intermodal group that allowed access to the rail grid site as a field-testing site outside of normal port operation hours. Transit New Zealand head office staff (Mark Owen, David Cook and Chris Parkman) are also thanked for their support of the research and in enabling access to historic SCRIM and RAMM data on the Transit New Zealand state Highway network. Land Transport New Zealand (formerly Transfund New Zealand) are acknowledged for their significant financial support of the research, in terms of the Land Transport New Zealand Research project that allowed the field research data collection and analysis programme to continue for a further year and for the extension to the controlled laboratory testing.

It has been well proven that as the skid resistance of a road surfacing decreases, the number of loss of control type crashes increases, causing road death and injuries. However, the management of skid resistance of road surfacings continues to be difficult due to the inherent and sometimes random variation in skid resistance levels over time. This study is an investigation and analysis of seasonal and short term variation of measured skid resistance in two phases. Phase 1: Regular field monitoring was undertaken using the GripTester and the Dynamic Friction Tester measurement devices on seven sites in the Auckland and Northland Regions of New Zealand was undertaken over a three year period. The effects of temperature, rainfall, contaminants, new surfacings, geometric elements and aggregate properties were analysed to investigate factors that initiate changes in the measured skid resistance of pavement surfacings. Phase 2: Laboratory prepared samples were constructed for accelerated polishing and skid resistance testing of four different aggregates (two greywackes, a basalt and an artificial iron-making melter slag aggregate). The samples were polished in an accelerated polishing machine to an ‘equilibrium skid resistance’ level (Stage 1 polishing). Contaminants were then added to the accelerated polishing process to determine the effect of varying additive, particle size and hardness in an attempt to simulate seasonal and/or short-term variations that occur in the field. The results have demonstrated that significant and previously unpredictable variations (greater than 30%) in measured skid resistance can occur over short time periods. These variations cannot be explained by any one factor. They are the result of a number of inter-related factors, including the geological properties of the aggregates and the contaminants themselves, the previous rainfall history, the road geometry, the calendar month of the year and (depending upon the measurement device), the temperature during testing. The laboratory tests demonstrate that accelerated polishing tests of aggregate samples could be prepared for testing by the Dynamic Friction Tester and that significant variations in measured skid resistance could be simulated on various aggregates in the laboratory by the addition of contaminants. The results of the testing and addition of contaminants on various aggregates resulted in significant behavioural differences which were related to the geological properties of the aggregates themselves, as well as the contaminants used in the accelerated polishing process. The findings of the research have specific relevance to three areas of industry; Road Controlling Authorities who are primarily interested in skid resistance policy, standards and management, Road Asset Managers who operate, maintain and manage condition level and the safety aspects of the road network and Crash Investigators who collect and analyse crash data primarily for legal proceedings. All three of these industry organisations need to clearly understand the inherent variability of skid resistance, the factors involved and the effects that geological and environmental variations have on skid resistance measurement. / Specific appreciation (as outlined below) is given to the significant industry partners/supporters that have helped support the research in many different ways. Firstly, I must give special thanks to Works Infrastructure Limited who have supported the research both financially and with resources almost from the outset of the research programme. The field testing data collection in the Northland Region of New Zealand would not have been possible without the support of the Whangarei Works Infrastructure team which included Peter Houba, Peter King, Matthew Findlay, Glen Kirk and the temporary traffic control team headed by Derek Phillips. Thanks also go to the Auckland Works Infrastructure testing laboratory which supplied aggregate supplies for laboratory sampling and testing and whose technicians also undertook Polished Stone Value tests on the aggregate samples. Special thanks are also given to Michael Haydon and David Hutchison from the technical management team of Works Infrastructure who have always been willing to listen to my requests and the many discussions that we have had on aspects of skid resistance, policy and technical matters. Pavement Management Services and especially Dr John Yeaman and Daniel Rich for their support for the research programme from the beginning, and secondly for financially contributing to the purchase of the Dynamic Friction Tester for the static field testing and the laboratory tests. Achnowledgement is also given to The Ports of Auckland and especially Jo Campbell of the AXIS Intermodal group that allowed access to the rail grid site as a field-testing site outside of normal port operation hours. Transit New Zealand head office staff (Mark Owen, David Cook and Chris Parkman) are also thanked for their support of the research and in enabling access to historic SCRIM and RAMM data on the Transit New Zealand state Highway network. Land Transport New Zealand (formerly Transfund New Zealand) are acknowledged for their significant financial support of the research, in terms of the Land Transport New Zealand Research project that allowed the field research data collection and analysis programme to continue for a further year and for the extension to the controlled laboratory testing.