Compaction Roller Research Articles

Predicting gaps and overlaps in automated fiber placement composites by measuring sources of manufacturing process variations

Manufacturing variations in the automated fiber placement (AFP) process are one of the causes of gaps and overlaps. These manufacturing variations can be due to robot inaccuracy, tow lateral movement on the roller, tow width variation or tow compaction. An experimental setup was built to measure and investigate these various sources of manufacturing variations and their relative contributions to gap and overlap defects. This setup consisted of a commercial AFP head instrumented with additional sensors. Among all the measured sources of variations, lateral movement of the tow on the compaction roller was the biggest contributor to gaps and overlaps. The distributions of these sources of variations were fit with probability density functions. Random samples from these fits were used to simulate adjacent tows and predict the occurrence of gap and overlap defects. The distribution of predicted gaps correlated closely with the distribution of experimentally measured gaps. Thus, this approach of using statistical information about the sources of manufacturing variations to predict the frequency and magnitude of defects in a layup was validated.

Field Evaluation and Application of Intelligent Quality Control Systems

During road construction, the accuracy of compaction work is critical for the structural stability and maintenance of the road. Although the plate load test (PLT) is commonly used for quality inspections, it is impractical to test every section due to time and cost constraints. Therefore, simpler testing methods are being extensively developed. This study compared quality inspection results using the commonly used PLT, the relatively simple dynamic cone penetrometer test (DCPT), the lightweight deflectometer (LWD) test, and an intelligent quality control system equipped with accelerometer and global positioning system (GPS) sensors in intelligent compaction (IC) rollers. The results showed a strong correlation between the conventional tests (PLT, DCPT, and LWD) and the values obtained from the intelligent quality control system. The correlation analysis between the intelligent quality control system and PLT, LWDT, and DCPT yielded R-square values of 0.69, 0.91, and 0.95, respectively, indicating significantly high correlations. The implementation of intelligent quality management systems in earthwork construction projects will facilitate a thorough verification of the compaction quality throughout all construction segments, ensuring consistent compaction across the project. By enabling real-time data acquisition and analysis, these systems differ markedly from traditional methods, reducing the frequency and necessity of manual inspections. This approach not only streamlines construction processes, but also enhances operational efficiency. As a result, integrating these intelligent systems is anticipated to significantly increase productivity by optimizing the workflow and resource utilization in earthwork construction.

Assessment of In Situ Compactness and Air Void Content of New Asphalt Layers Using Ground-Penetrating Radar Measurements

This paper deals with the possibilities of ground-penetrating radar (GPR)-based quality control testing, which was demonstrated on an experimental road section of a ~220–240 m long Hungarian residential street. The measurements and their assessment aimed to control the prescribed compactness and air void content of newly built asphalt layers. Research has discussed the relationship between the air void content and the dielectric constant of asphalt layers, and provided empirical results for this relationship. We suggest a new logistic model with lower and upper asymptotes instead of the exponential formula often used in the literature. Contrary to this newly developed robust model, existing models are sensitive to extreme dielectric constant values due to the mathematical nature of their exponential function. The results of the new logistic model are compared to those of the Hoegh–Dai (HD) and Minnesota Department of Transportation (MnDOT) models on the basis of a few calibration data points. Through systematic data collection and analysis, the developed robust empirical model demonstrates a significant correlation between the relative permittivity and air void content in asphalt mixes, enabling accurate estimation of the air void content within a ±0.5% margin of error. The air void content can be applied to estimate the asphalt layer modulus. The developed model can be further exploited by utilizing a combination of GPR and drone technology. The “symbiosis” of these technologies can lead to a totally non-destructive imaging system, which can then be applied to environmental monitoring of roads and their surroundings in terms of quality control of asphalt compaction work and the hot asphalt mix behind the compaction roller during pavement construction.

Learning from data to improve asphalt road construction processes

Asphalt road construction projects pose a lot of challenges in different disciplines, from the choice of construction methods, type and quantity of machines and personnel, pre-planning of all processes, ordering material from asphalt mixing plants, real-time logistics of handling material transport, and the asphalt paving and compaction process itself. Depending on the complexity and size of the construction site, preparation and execution can be influenced by a lot of unknown variables, like weather impact, material properties of the delivered asphalt or delays in the deliveries themselves. These circumstances might lead to irregularities in the asphalt material temperatures and thus suboptimal conditions for compaction or even construction stoppage - in any case, they lead to a reduction in quality of the built asphalt road. In recent years, a lot of mobile devices, sensors and software have been emerging as viable solutions in the construction industry to digitize and support these processes. Those real-time applications allow deeper insight into logistics or material properties on site and acquire data for downstream analysis. These endeavours in process optimization now benefit construction companies to increase efficiency, and for work safety and environmental aspects, it is crucial to optimize energy and CO2 consumption. Improved logistics and building roads with low-temperature asphalt will have to become a standard in road construction. The present study gives an overview of the digitalized processes in asphalt road construction with market-available solutions focusing on logistics data of the material delivery chain from mixing plant to paver, thermal imaging data of the built asphalt to validate asphalt temperatures, as well as machine and location data from asphalt paver and compaction rollers.

Experimental research procedure of roller forming unit

Experimental research is conducted followed by a comparative analysis of the results, which are obtained in the process of theoretical and experimental studies, to check the theoretical research adequacy of the roller forming unit with the crank drive.
 We have developed the experimental research program for the roller forming unit with the crank drive. The research stand of roller forming with the crank drive was used for experimental studies. This research stand allows you to carry out full-value experimental studies on the determination of dynamic loads unrestricted. The experimental research program provides the determination of the interaction force for the compaction roller with the construction mixture, the force in the unit connecting rod, the torque on the unit drive shaft and the power, which is necessary for the realization of the forming process. The determination of these loads will make it possible to realistically assess the condition of the forming unit and rationally carry out its design and operation.
 Plan, procedure and processing of experimental research data have been developed. The measuring and recording equipment were selected to determine the force loads of the research stand for conducting experimental studies, which transforms the received numerical data into Microsoft Excel for their processing. The measurement of the force in the connecting rod and the interaction vertical force of the compaction roller with the construction mixture was carried out using strain gauges. These are pasted according to the bridge scheme on the connecting rod and the metal plate, which is located in the form with the building mixture under the compaction roller. RK 435 universal clamps, which make it possible to measure the line voltage, the current strength and the power under unit different load modes, are used to measure the power required for the forming process.

Experimental study of automated soil density control system of garlic planting machine

An automated system for adaptive regulation of soil density has been developed, which makes it possible to improve the quality of garlic incorporation when planting within the range of soil density regulation in the range of 1.2 -1.4 g/cm?. A methodology has been developed for conducting experimental studies of a machine for planting garlic with an installed automatic monitoring and control system for regulating soil density during planting. The results of experimental studies of the uniformity of soil compaction using a compaction roller with an automatic density control system and a closing device represented by a skid-type harrow indicate that after passing through a skid-type harrow, the value of the studied parameter increased by 18% relative to the initial state of the soil. The results of experimental studies of the quality indicators of the planting machine without an automatic monitoring and control system indicate a deterioration in the quality of the process of planting garlic bulbs with increasing forward speed in the range from 0.8 to 1.2 m/s at values of the coefficients of variation of the depth of planting of garlic bulbs ?_Hl from 32% to 42%. The results of experimental studies of the influence of a digital system for automatic control and management of garlic planting indicate the prospects of conducting research in this direction, which is confirmed by an increase in the quality indicators of the planting machine by 15% in comparison with the closing organ in the form of a skid-shaped harrow.

A Study on the Analysis of the Ground Compaction Effect According to the Roller Operation Method through CMV Analysis Using IC Rollers

In road construction, the compaction process using vibratory rollers is essential to increase the ground stiffness in earthworks. There need to be clear standards regarding the operation of compaction rollers during compaction work. Various simple quality inspection techniques have been developed to check the stiffness of the ground, but plate load test and field density test are the most commonly used test methods to evaluate the degree of compaction during road construction. However, both inspection methods could be more efficient, as they cannot be performed in all sections due to time and cost. Additionally, in compaction work today, the worker will individually judge the number of compactions, thickness, speed, vibration etc. based on his or her own experience. This means that the quality of compaction varies depending on the worker. In this study, quality inspection results for all sections were obtained using an intelligent quality control system that employs an IC roller, a technology that is now commercially available. The effect of the operating conditions of the vibrating roller (roller compaction direction, compaction roller speed, and compaction roller vibration method) on the compaction quality was analyzed using the intelligent quality control value. Through our highway construction site tests, it was found that the speed of the compaction roller and the vibration method of the compaction roller affected the degree of compaction, but the direction of compaction did not. Therefore, if the compaction work is performed by adjusting the driving speed and vibration method of the vibrating roller according to the ground conditions, repetitive compaction work can be reduced, thereby reducing construction costs and lowering work time, which will achieve an improved work efficiency.

Realization of combined dynamic motion mode for roller forming unit

The combined dynamic mode of the reciprocating motion for a forming trolley is calculated to increase the reliability and durability of the roller forming unit. The criterion action is used as a criterion of the motion mode, which is an integral over time with the sub-integral function that expresses the acceleration «energy» when calculating the combined dynamic motion mode of the forming trolley in the acceleration and braking areas. The change functions of the kinematic characteristics of the forming trolley during its motion from one extreme position to another, which correspond to the combined dynamic mode of the reciprocating motion, are calculated. The displacement and speed of the forming trolley in the acceleration and braking areas change smoothly with this motion mode, without creating significant dynamic loads in the unit, which in turn has a positive effect on its durability.
 The variation law of the compaction rollers angular velocity is calculated by taking into account the change functions of the forming trolley speed. The roller forming unit design with a drive from the high-torque stepper motor is proposed, which is mounted in the compaction rollers of the forming trolley and provides the combined dynamic mode of reciprocating motion for the forming trolley. The surface quality of the processed concrete mixture is increased, dynamic loads in the drive mechanism elements are reduced, unnecessary destructive loads on the frame construction are disappeared and, accordingly, the reliability and durability of the unit as a whole are increased, when we use the such drive in the unit.

Analysis of roller compaction pressure distribution in automated dry fibre placement

Automated Dry Fibre Placement (ADFP) is a version of Automated Fibre Placement (AFP) where prepreg tapes are substituted with dry fibre tapes. In this process, a uniform compaction pressure applied by a compaction roller is required to manufacture preforms with consistent quality. In this paper, a finite element model is developed to analyse the roller-applied pressure on the fibrous reinforcement bed. The model has been validated by using a pressure sensitive film. The influence of roller material, tool curvature and substrate thickness on the pressure distribution are investigated. Increasing tool curvature leads to a decrease in compaction pressure uniformity using the same compaction force. Force input target bounds for different rollers on tools with different curvatures are determined using the model. It is found that softer rollers show large force control window and suitability for tools with higher curvature. Thick substrates exhibit large deformation which could increase complexity for force control strategies.

Effect of Roller Pressure and Base Prepreg Layer on Tensile and Flexural Properties of CFRP Laminates Fabricated Using Automated Fiber Placement

Composites can be manufactured in numerous ways. Among the available methods, Automated Fiber Placement (AFP) is the most advanced and latest technology utilized by companies for aerospace and other projects. Although it offers many benefits, it has unique manufacturing challenges and quality issues. The presence of tow placement defects such as tow gaps, tow overlaps, twisted tows, incomplete tows, and missing tows in the AFP process are causes for concern as these lead to a decrease in the mechanical performance of the fabricated parts. Although it is not possible to completely avoid the occurrence of defects, optimizing key process parameters is a possible way to minimize them. Roller pressure is one such parameter. If it is too high, it can lead to wider and thinner tows and if it is too low, the towpreg may not stick properly to the substrate and hence, not conform to curvatures. In this work, test layups of different configurations using carbon (T700SC-24K-50C) towpreg with epoxy (UF 3376-100) as the matrix system were prepared at different compaction roller pressures (2 bar, 3.5 bar, and 5 bar), with and without the presence of base prepreg layers. Tensile and bending tests were respectively carried out according to ASTM D3039 and ASTM D7264 to study the effects of these process parameters on the layup defects. From the test results, it is found that using a compaction roller pressure of 3.5 bar and a base prepreg layer of the same material as the towpreg, leads to minimum defects, and hence, to the best tensile and bending properties.

Effects of processing parameters of infrared-based automated fiber placement on mechanical performance of carbon fiber-reinforced thermoplastic composite

This study investigates the influence of processing parameters of infrared-assisted automated fiber placement (AFP) on the mechanical and thermal properties of carbon fiber-reinforced thermoplastic composites. In particular, two processing parameters—compaction force and tool temperature—with two compaction roller types were analyzed based on the design of experiments with four distinct process conditions. Accordingly, we conducted experiments to determine the optimum process parameters and maximize the bending and bonding strengths. For each condition, the flexural and lap-shear strength (LSS) analyses along with thermal analysis were performed to investigate the impact of the process parameters and conditions. Moreover, the pressure films were used to examine the pressure distribution of the compaction roller. The failure modes of the LSS and flexural samples were observed under scanning electron microscopy and visual inspection. The correlation between the process parameters and the thermal and mechanical properties was derived for various parametric combinations. Overall, the results revealed that a higher tool temperature significantly increased the flexural strength of the AFP-fabricated composites. The samples fabricated with the elastomeric compaction roller displayed a higher degree of crystallinity with higher LSS and flexural strength compared to those fabricated with a steel compaction roller. This study provides comprehensive insights into the manufacturing and mechanical performance of carbon fiber/polyamide 6 composites with infrared-assisted AFP.

Experimental Validation of Traction Control of Compaction Roller Towed by Small Mobile Robot

Experimental Validation of Traction Control of Compaction Roller Towed by Small Mobile Robot

Realization of optimal motion jerky mode for roller forming unit

The optimal jerky mode of the reciprocating motion for a forming trolley is calculated to increase the reliability and durability of the roller forming unit. The criterion action is used as a criterion of the motion mode, which is an integral over time with the sub-integral function that expresses the jerk’s «energy» when calculating the optimal motion jerky mode. The change functions of the kinematic characteristics for the forming trolley are calculated. The variation law of the compaction rollers angular velocity is calculated by taking into account the change functions of the forming trolley speed. The roller forming unit design with a drive from the high-torque stepper motor is proposed, which is mounted in the compaction rollers of the forming trolley and provides the optimal jerky mode of reciprocating motion for the forming trolley. The surface quality of the processed concrete mixture is increased, dynamic loads in the drive mechanism elements are reduced, unnecessary destructive loads on the frame construction are disappeared and, accordingly, the reliability and durability of the unit as a whole are increased, when we use the such drive in the unit.

Predicting and Improving Interlaminar Bonding Uniformity during the Robotic Fiber Steering Process.

With their high specific stiffness, corrosion resistance and other characteristics, especially their outstanding performance in product weight loss, fiber-reinforced resin matrix composites are widely used in the aviation, shipbuilding and automotive fields. The difficulties in minimizing defects are an important factor in the high cost of composite material component fabrication. Fiber steering is one of the typical means of producing composite parts with increased strength or stiffness. However, fiber waviness is an important defect induced by fiber steering during the fiber placement process. Meanwhile, the laying speeds of the inner and outer tows along the path width direction are different during the fiber steering process, resulting in different interlaminar bond strengths. Therefore, the fiber waviness and uneven interlaminar bonding strength during fiber steering not only affect the dimensions of a composite product, but also influence the mechanical properties of the part. This study aims to reduce fiber waviness and improve interlaminar bonding uniformity along the path width direction using a multi-piece compaction roller. By analyzing the mechanism of the generation of fiber waviness, the interlaminar bonding strength for each tow during fiber steering is investigated. Through analyzing and optimizing the compaction force, laying temperature and laying velocity during fiber steering experiments, the optimization approach is verified.

Experimental study of particle lift initiation on roller-compacted sand–clay mixtures

Civil engineering works are sources of dust emissions, which can cause severe security, health and environmental damages to workers and neighbourhoods. This is particularly significant for implementation of earthwork sites. The present paper reports a study conducted to characterise the soil–atmosphere interaction above compacted soils where particle lift is initiated. Mixtures of kaolin clay and sand have been compacted using a laboratory roller compactor that reproduces near-field compaction conditions. Shear testing conducted at the interface confirms that the sand content affects the friction angle between the soil and the compaction roller. The experimental velocity profiles above the compacted samples have been obtained in a wind tunnel using a non-intrusive measurement technique (laser Doppler velocimetry). Results show that the sand fraction affects velocity profiles. Compaction, therefore, may not fully reduce the roughness of the soil surface. The airflow friction velocities at the sample surfaces have been determined from the boundary layer profiles. The results achieved demonstrate that all tested soils reach the threshold friction velocity required to initiate particle lift, and the higher the sand content of the soil, the more likely it is that particle lift occurs.

In situ consolidation of carbon fiber PAEK via laser-assisted automated fiber placement

Automated fiber placement (AFP) of thermosetting composites has been one of the leading manufacturing techniques for aerospace structures over the last decade. Thermoplastic composites (TPCs) offer several advantages including a high toughness, recyclability, weldability, and potential for rapid out-of-autoclave manufacturing. High-power heating sources and flexible compaction rollers can be used to melt and consolidate TPC tapes via AFP to form large structures in a layer-by-layer manner as used in additive manufacturing. This paper investigates the in-situ consolidation AFP of TPC tapes (ICAT) toward their process optimization and revealing mechanisms that govern the ICAT process. To this end, a laser-assisted AFP system was utilized to fabricate short beam strength samples from carbon fiber reinforced low-melt polyaryletherketone (LM-PAEK™) at various processing parameters. Analysis of results revealed how ICAT process parameters affect interlaminar bonding, crystallinity, and void content in manufactured parts. Multiphysics finite element analysis (FEA) was also carried out to reveal mechanisms that control void, crystallinity, and bonding in ICAT. Finally, a comparison of post-fracture specimens made via ICAT with traditional compression molding was used to explain the underlying failure mechanisms in ICAT coupons. This study shows that at AFP rates of up to 0.15 m/s, high interlaminar shear strengths, up to 60 MPa, are possible to achieve with low void content (<1%) and high crystallinity (>20%), proving that ICAT is potentially a viable process for manufacturing the next generation of aerospace composites.

Development and Assessment of an Intelligent Compaction System for Compaction Quality Monitoring, Assurance, and Management

The successful quality control and quality assurance of compaction operations are vital for the long-term performance of earth structures. Traditional in situ measurement methods are in practice for assessing compaction project specifications. These methods have several shortcomings and cannot provide complete compaction quality information. With the advancement in automation and information technology in the construction section, intelligent compaction roller technology has the potential to solve this problem. However, this technology still has many problems and needs more comprehensive studies for its implementation. This study focuses on the development of a Web-GIS-based intelligent compaction system and the assessment of the practical application of this technology. The developed system consists of major components—namely, system hardware and software—to provide real-time compaction information and an effective management system. An experimental study was conducted to assess the correlation between the developed system’s compaction quality and traditional measurement methods. The linear regression analysis identifies the strong correlation and promises the feasibility of an intelligent compaction system instead of a traditional in situ test for compaction quality control. Two implementation case studies of real-time projects are presented to validate and demonstrate the practicality of the developed system.

Design of an Innovative Tractor-Operated Seeder for Mat Type Paddy Nursery

This study contains the design approach, development details, and field evaluation of an innovative tractor-operated seeder for sowing mat type paddy nursery. In order to design and select the various components of mat type nursery seeder, the fundamentals of farm machinery design were taken into due consideration. The machine comprises of soil cutting unit, inclined conveyor unit, screw type conveyor auger, sieving unit, compaction roller, polythene sheet laying unit, soil metering and seed metering unit. The basic criteria for design were to prepare a soil bed with a width of 1000 mm and width of cut of channel 240 mm on both sides of the bed to irrigate the prepared soil bed. The soil cutting unit and conveyor unit were designed based upon amount of soil required on soil bed to have 20–30 mm soil mat bed thickness and seed metering unit was designed to deliver 2–3 seeds∙cm−2 on the bed. The machine was fabricated based on design calculations and then evaluated in laboratory as well as actual field conditions. During field evaluation of this machine, it was found that the coefficient of uniformity for seed spread was 7.33%, coefficient of uniformity for soil spread 5.67%, fuel consumption 39.6 l.ha−1 and actual field capacity 0.11 ha∙h−1 with 1.7 km∙h−1 forward speed of machine. Labour saving using the designed tractor-operated seeder was observed to be 86.4% as compared to the manual method of sowing mat type nursery using steel frames.

Prediction of average in-depth temperature of asphalt pavement using surface temperature measured during intelligent compaction

ABSTRACT This paper presents a novel equation (named the ‘STKAR equation’) to predict the average in-depth temperature of asphalt layers in real-time during compaction using the measured surface temperature and the estimated temperature gradient at the asphalt surface. The motivation for the development of this method is the fact that the asphalt surface temperature measured during asphalt compaction using infrared radiation (IR) sensors mounted on state-of-the-art intelligent compaction (IC) rollers does not represent the average temperature in the asphalt layer, which governs its mechanical properties. Further, current asphalt temperature prediction models require the elapsed time since asphalt paving to predict the in-depth temperature of the asphalt layer during compaction. However, the measurement of elapsed time for each spot on the asphalt layer during compaction has practical difficulties in the field. In this study, the STKAR equation was derived from the 1-D diffusion equation for the cooling process of a newly-laid hot asphalt layer during compaction in the field. The developed equation was validated using the temperature data obtained during the construction of a two-layer asphalt testbed in the field. The in-depth temperatures predicted using the STKAR equation showed excellent agreement with the in-depth temperatures measured in asphalt layers during compaction. Further, numerical simulations were carried out to examine the applicability of the STKAR equation to different field scenarios. The numerical results showed that the initial temperature of the asphalt mix, the thermal conductivity of the underlying support material and the initial temperature of the underlying support significantly affect the in-depth temperature profile of asphalt layers, while asphalt density and asphalt specific heat content have negligible effects on the in-depth temperature profile. The STKAR equation was further refined by incorporating the factors which affect the in-depth temperature profile of asphalt layers during compaction.

Research on Void Dynamics during In Situ Consolidation of CF/High-Performance Thermoplastic Composite

Automated fiber placement (AFP) in situ consolidation of continuous CF/high-performance thermoplastic composite is the key technology for efficient and low-cost manufacturing of large thermoplastic composites. However, the void in the in situ composite is difficult to eliminate because of the high pressure and the short consolidation time; the void content percentage consequently is the important defect that determines the performance of the thermoplastic composite parts. In this paper, based on the two-dimensional Newtonian fluid extrusion flow model, the void dynamics model and boundary conditions were established. The changes of the void content percentage were predicted by the cyclic iteration method. It was found that the void content percentage increased gradually along the direction of the layers’ thickness. With the increasing of the laying speed, the void content percentage increased gradually. With the increasing of the pressure of the roller, the void content percentage gradually decreased. When the AFP speed was 11 m/min and the pressure of the compaction roller reached 2000 N, the void content percentage of the layers fell below 2%. It was verified by the AFP test that the measured results of the layers’ thickness were in good agreement with the predicted results of the model, and the test results of the void content percentage were basically equivalent to the predicted results at different AFP speeds, which indicates that the kinetic model established in this paper is representative to predict the void content percentage. According to the metallographic observation, it was also found that the repeated pressure of the roller was helpful to reduce the void content percentage.