Forest fires are still a serious global problem.Therefore, designing of modern forest fire fighting machines is an important problem.This paper deals with the investigation of reliability of forest fire fighting system at the design stage by using fracture mechanics and possibility theory application.Usage justification and some advantages of using wheeled forwarders as basic machines for the installation of forest fire fighting systems are presented in the introduction.The basic fracture mechanics equations linking stress intensity factor with crack-like defect length are presented in the first part of the paper.Fracture toughness and crack-like defect length are viewed as Gaussian random values; maximum applied stress is presented as a fuzzy variable with unknown distribution law.Analytical equations for reliability evaluation are obtained by estimation of upper and lower bounds of reliability function.The real value of this measure is located within this interval.The estimation of reliability function by the example of the supporting frame of a modular firefighting system based on forwarder Amkodor-2661 is presented in the second part of the paper.The stress intensity was determined by the finite element method.The calculation is carried out for the variant of presence of an edge type of crack in material.The interval of reliability function values is calculated.It is important to know the upper value of failure probability and, accordingly, the lower one as the most provided value of reliability function.

The working conditions of forestry machines differ from those of agricultural machines. The presence of obstacles during the clearing of forest areas increases loading of machine components and assemblies and, consequently, leads to their failures. This paper deals with an improvement of probabilistic methods of forestry machine design by applying fracture mechanics and possibility theory. The main fracture mechanics expressions linking stress intensity factor with crack-like defect length are presented in the introduction. Fracture toughness and crack-like defect length are viewed as Gaussian random values, maximum applied stress is presented as a fuzzy variable with unknown distribution law in the second part of the paper. Analytical equations for reliability evaluation are obtained by estimation of upper and lower bounds of reliability function. The real value of reliability function is located within this interval. The proposed approach may be applied to give recommendations for engineering of forestry machine and equipment elements in the case of limited statistical information.

Maintenance of forestry and agricultural machines, in addition to their configurations, is facing many challenges, one of them being extensive fragmentation over territories, which creates conditions for multiple practices to keep equipment operational, starting with field conditions and ending with specialized enterprises. The choice of the most efficient option in terms of location and technology (with due account for varying structural complexity of functional units) in order to ensure the best quality and cost-effectiveness of maintenance and repair is an important task in improving the efficiency of operating conditions, and, therefore, of the entire production that rests on them. The paper discusses a set of interrelated provisions to provide a rationale for factors characterizing the efficiency of practices to keep forestry and agricultural machines in satisfactory operational condition. The paper focuses on a comparative assessment of the ease with which these machines can be maintained and repaired while being in operation, as well as on predictions of maintainability indicators at the design stage to ensure their competitiveness and economic efficiency.

Работа посвящена оценке влияния эксплуатационных факторов на ремонтопригодность лесных машин. Цель работы заключается в обосновании и апробации порядка оценки факторов, определяющих ремонтопригодность транспортно-технологических машин, с использованием методов корреляции и регрессии. В первой части статьи представлен краткий обзор статистических методов анализа факторов эксплуатационной технологичности. Вторая часть статьи посвящена построению уравнения регрессии и определению значений коэффициентов в модели. В качестве факторов, определяющих продолжительность технических воздействий, приняты длительность эксплуатации лесных машин, стаж работы ремонтных рабочих и техническая оснащенность ремонтной базы. Связь между факторами и продолжительностью технических воздействий представлена в виде множественной линейной модели. В качестве показателей тесноты связи между исследуемыми переменными величинами использованы парные коэффициенты корреляции. Для определения коэффициентов регрессии линейной модели использована система нормальных уравнений. В третьей части статьи проведен анализ полученного уравнения регрессии. В качестве критерия правильности и полноты отбора факторов использован коэффициент детерминации. По полученной величине критерия был сделан вывод о достаточно высоком уровне полноты учета совокупности факторов, влияющих на продолжительность технического обслуживания и ремонта машин. Проведена проверка значимости коэффициентов уравнения регрессии с использованием критерия Стьюдента. По результатам проверки все рассматриваемые факторы признаны значимыми для оценки продолжительности технических воздействий. Наибольшее влияние на продолжительность технических воздействий оказывает техническое состояние машины, зависящее от длительности её эксплуатации. Влияние стажа работы (квалификации) исполнителей и уровня оснащенности ремонтно-обслуживающей базы незначительно отличаются друг от друга, однако уровень оснащенности ремонтной базы является более значимым. The paper deals with the estimation of operational factors affecting forest machine maintainability. The main goal of this study is to substantiate and test the order of operational factors estimation using correlation and regression methods. A brief description of statistical methods of operational factor analysis is presented in the first part of the paper. The second part of the paper presents the obtained multiple regression equation and determined values of beta coefficients. Operation time of forest machine, staff employment period and servicing base technological infrastructure are accepted as independent variables determining servicing time. The interaction between independent variables and servicing time is presented as a multiple equation of linear regression. Pair correlation coefficients are used as indices of close linkage among the analyzed variable quantities. The system of normal equations is used to determine the regression coefficients of the linear model. The analysis of the obtained regression equation is given in the final part of the paper. The coefficient of determination is used as the accuracy and completeness criterion of factor selection. According to the obtained value of the criterion, it was concluded that the level of completeness of factor selection is sufficiently high. The statistical significance of regression coefficients is verified using Student's test. All considered factors are recognized as significant for servicing time estimation according to the results of verification. Furthermore, operation time of forest machine is recognized as the general maintenance factor affecting the duration of technical impacts. The effects of the staff employment period and the servicing base technological infrastructure differ slightly from each other; however, the servicing base technological infrastructure factor is more significant.

In this work the technique of improvement of transport and technological vehicles maintenance is presented. A high-quality organization of technical service is impossible without determining the characteristics of the intensity of requests for a certain type of repair work. The failure flow as a set of successive failures of parts and assembly units is considered as a stationary Poisson process. The check of the stationarity of the failure flow was carried out using the Pearson criterion. The presented technique for researching the failure flow can be extended to any structural elements of technological machines. The results of calculations using this technique can be used, for example, to organize a rational supply of spare parts in order to reduce downtime and material losses during the technical operation of equipment.

The algorithm for the best development and delivery of a multi-item set of spare parts (SP) and/or maintenance supplies (MS) from the warehouse of the manufacturer or the central warehouse of the dealer to remote/geographically dispersed consumers that use a certain type of equipment. The solution to this problem is very important in order to improve the efficiency of the technical operation of machines and equipment used in any business. Market economy conditions require a strong need in spare parts and a new level of monitoring and management of the spare part provision system for machines and equipment. The article concerns the automation of the management decision making process and practical implementation of the algorithm based in the method that takes the form of a set of math models that take into account the sufficient number of factors and establish the right connections between the controlled and non-controlled variables. The controlled and noncontrolled parameters have been established, the structure of the algorithm for the implementation of math models allows to form a set of spare parts and choose a proper vehicle for the delivery of the set to the consumer. The multi-item set of spare parts must be flexible, both in terms of its composition and of the number of items on the list, the names of the parts that depend on the specific conditions of the delivery, including the operation conditions and the reliability of the serviced equipment. The establishment of the economically justified parameters for the delivery and stock set of spare parts for geographically distributed consumers should be conducted by the minimization of expenditures on the delivery and development of this analytical expression of the target function and the algorithm for its implementation when it comes to any equipment, including construction, agricultural or forest equipment.

This paper deals with the improvement of probabilistic methods of design by using the catastrophe theory and the possibility theory application. A brief description of the catastrophe theory is presented, the cusp catastrophe is considered, control parameters are viewed as fuzzy variables with unknown distribution laws in the first part of the paper. The definition of the possibility measure of the cusp catastrophe occurrence is given in the second part of the paper. The condition of the cusp catastrophe occurrence is formulated according to Zadeh’s extension principle. The proposed method can be applied to solve the problems of the technical systems reliability and to give recommendations for engineering of forest machine and equipment elements in the case of limited statistical information.

Current standards in the field of self-propelled machinery for forestry require equipping tractor cabins with roll-over protective structures (ROPS). It is necessary to reduce the risk of operator's injuries caused by tractor rollovers or falling trees. This article deals with the way of increasing the energy absorption capacity of forest machine cabin roll-over protective structure. The ability to absorb certain amount of potential energy during deformation is the one of basic requirements to cabin of a forest machine. The risk of injures to the operator is reduced by using energy-absorbing cab support in the construction of roll-over protective structure. The protective effect is attained by plastic strain of cab support elements, that provides operator's protection during an accidental roll-over. The article presents the design of the cab support, describes its functional principle in the event of an emergency

This paper deals with the statistical fracture mechanical method for the optimal design of forest machine components. The problem of optimal design includes the choice of the objective function and independent design variables and establishment of the system limits. The objective function is determined as the mean total cost that includes the initial cost and the cost of failure according to the failure probability. A quasi-brittle fracture occurs under the influence of the stationary random process of loading. Analytical equations of reliability function estimation are obtained. The algorithm of the random search method includes an interval reduction with regard to zone and functional constraints. The approach to the optimal design problem solution can be applied to obtain optimal geometrical sizes and permissible limit defect values of machine components.

В статье представлена апробированная методика оценки значимости факторов, определяющих стоимость технической эксплуатации машин. Для оценки факторов использован однофакторный дисперсионный анализ условий выполнения технических воздействий. Производительность технического обслуживания и ремонта зависит от места их проведения. Это могут быть полевые условия, ремонтно-механические мастерские, специализированные предприятия. В себестоимости продукции лесного комплекса до 30 составляют затраты на техническое обслуживание и ремонт машин. Исследование факторов, влияющих на эти затраты, является актуальным. В статье на конкретном примере осуществлена оценка значимости условий проведения технического обслуживания лесозаготовительной машины. Наилучшие условия проведения технического обслуживания в пунктах централизованного технического обслуживания. Это снижает продолжительность и повышает производительность работ. Методика оценки значимости факторов может быть применима к любым территориально распределенным машинам. Может быть оценена значимость механовооруженности ремонтно-обслуживающей базы, квалификация и стаж рабочих, возраст и наработка машин. Это является дальнейшим развитием работы. Дальнейшим развитием работы может быть использование двухфакторного и многофакторного дисперсионного анализа. Применение дисперсионного анализа позволяет оценить влияние количественных и качественных факторов. Сущность исследования значимости факторов заключается в разложении полной дисперсии на сумму дисперсий. Влияние каждого фактора на изучаемый признак оценивается его вкладом в полную дисперсию. Апробация оценки влияния способа организации работ, на длительность технического обслуживания осуществлена на примере тракторов Онежского тракторного завода (ОТЗ). Материалом для исследования явились данные эксплуатационных испытаний на надежность тракторов в условиях опорных пунктов Республики Карелия. Испытывались тракторы одной марки в пределах ресурсной наработки. Учитывалась длительность технических обслуживаний в условиях лесосеки, передвижных пунктов ремонта на верхнем складе, пунктов централизованного обслуживания, мобильными средствами. Наиболее эффективными явились условия пунктов централизованного технического обслуживания машин и оборудования. The paper deals with the tested method of estimating the significance of factors that govern the costs of forest machines operation. A single-factor analysis of variance was used for factor estimation. The productive capacity of technical maintenance and repair depends on the repair area location. It can be field conditions, mechanical repair shops or specialized enterprises. Technical maintenance expenses account for up to 30 of the total cost of forest complex production. Therefore the investigation of factors that affect these expenses is important. This paper contains an example in which the significance of forest machines technical maintenance conditions is estimated. The best conditions for technical maintenance are at centralized service points because there it is possible to decrease the servicing time and increase the work output. The proposed method of factor significance estimation can be applied to any geographically distributed machines. This method allows estimating the significance of such factors as the degree of maintenance and servicing base mechanization, the level of staff qualification and experience and the duration of machine operating time. The application of two-way and multivariate analysis of variance can be used in further wok development. The usage of variance analysis allows measuring theinfluence of quantitative and qualitative factors. The investigation of factor significance can be presented as the variance decomposition into a sum of variances. The influence of every factor is estimated as its contribution into the total variance. Onego Tractor Plant machines were used to test the influence of workflow management on the servicing time. This study is based on the results of tractor operation reliability tests at the service points in the Republic of Karelia. Tractors of the same models were tested within the similar operating time. The servicing time was considered for machines serviced at wood cutting areas, trucks workshops, centralized service points, or by using mobile maintenance and support equipment. The centralized service points were found as the most effective practices of forest machine technical maintenance.

This paper deals with the optimal design problem solution for the operator of an earth-moving machine with a roll-over protective structure (ROPS) in terms of the catastrophe theory. A brief description of the catastrophe theory is presented, the cusp catastrophe is considered, control parameters are viewed as Gaussian stochastic quantities in the first part of the paper. The statement of optimal design problem is given in the second part of the paper. It includes the choice of the objective function and independent design variables, establishment of system limits. The objective function is determined as mean total cost that includes initial cost and cost of failure according to the cusp catastrophe probability. Algorithm of random search method with an interval reduction subject to side and functional constraints is given in the last part of the paper. The way of optimal design problem solution can be applied to choose rational ROPS parameters, which will increase safety and reduce production and exploitation expenses.

Работа посвящена решению задачи оптимального проектирования устройства защиты оператора при опрокидывании лесной машины с применением методов теории катастроф. В первой части статьи представлено введение в теорию катастроф, приведена катастрофа сборки, при этом переменные управления рассмотрены как случайные величины, распределенные по нормальному закону. Вторая часть статьи посвящена постановке задачи оптимального проектирования, включающей выбор целевой функции и параметров проектирования, определение системных ограничений. Целевая функция определена в виде средних суммарных ожидаемых затрат, включающих затраты на производство конструкции и стоимость ее отказа с учетом вероятности катастрофы сборки. В третьей части статьи приведен алгоритм поиска оптимального решения, в основу которого положен метод случайного поиска с уменьшением интервала при учете областных и функциональных ограничений. В заключительной части статьи представлен пример решения оптимизационной задачи при выборе рациональных параметров защитного устройства, позволяющий повысить безопасность труда и снизить затраты при изготовлении и эксплуатации конструкции.

Работа посвящена оценке показателей надежности машин с позиций теории катастроф. В первой части статьи приведена катастрофа сборки, при этом параметры управления рассмотрены как стационарные случайные процессы (функции) и поставлена задача о выбросах. Полученные аналитические зависимости дают возможность оценки вероятности безотказной работы, вероятности отказа (вероятности катастрофы сборки), средней наработки до отказа. Для определения характеристик случайного процесса (математического ожидания и дисперсии) использован метод статистической линеаризации. Во второй части статьи проанализирована возможность применения методов теории катастроф для проектирования элементов конструкций технологических машин и оборудования на примере защитного устройства кабины колесного трелевочного трактора. Предложенный подход позволяет произвести статистический анализ положений равновесия вблизи критических точек. Полученные зависимости могут быть применены для оценки вероятности безотказной работы различных элементов конструкций машин и оборудования с позиций теории катастроф.

FIELD: transport. SUBSTANCE: invention relates to transport engineering. Claimed support comprises the thermally-treated draw ring with conical working zone connected with cabin protective belt, fastening bolt, pad nut and damper secured ion the guide coupled with the logging machine frame. The cabin fastening bolt is fitted in the draw ring channel. The diameter of the bolt section without thread equals the maximum diameter of the draw ring working zone. Ratio between diameters of said unthreaded and threaded bolt sections varies from 1.12 to 1.20. EFFECT: higher cabin safety. 5 dwg

This paper deals with the estimation reliability measures from the point of catastrophe theory. An introduction to the catastrophe theory is presented, cusp catastrophe is considered and analysis of control parameters critical values is carried out at the fi rst part of the paper. Control parameters are viewed as stationary random processes (functions) and problem of overshoot of random function is formulated. Mean number of zero crossings by random stationary process was evaluated at the next stage of the research. Analytical equations can be applied for defi nition of reliability function, failure probability (cusp catastrophe probability), mean operating time to failure. The statistical linearization method used for determination of random process characteristics (mean value, dispersion). Statistical analysis of balance near critical points can be carried out by this approach. These expressions can be applied for estimation of reliability function of machines and equipment construction elements from a perspective of catastrophe theory.

В работе приведен метод оценки показателей надежности с позиций теории катастроф. В первой части статьи представлено введение в теорию катастроф, рассмотрена катастрофа сборки и проведен анализ критических значений управляющих параметров. Параметры управления рассматривались как стационарные случайные процессы (функции) и ставилась задача о выбросах. На следующем этапе исследований определялось среднее число пересечений нулевого уровня стационарным случайным процессом. Полученные аналитические зависимости дают возможность оценки вероятности безотказной работы, вероятности отказа (вероятности катастрофы сборки), средней наработки до отказа. Для определения характеристик случайного процесса (математического ожидания и дисперсии) использовался метод статистической линеаризации. Предложенный подход позволяет произвести статистический анализ положений равновесия вблизи критических точек. Полученные зависимости могут быть применены для оценки вероятности безотказной работы различных элементов конструкций машин и оборудования с позиций теории катастроф.

Анализ функционирования зоны ремонта предприятия технического сервиса лесной отраслиА. В. Питухин 1 И.Г. Скобцов Н. И. Серебрянский А

This paper deals with the methodical way of definition the indicators of technical service enterprise’s capacity by probabilistic and statistical methods in conditions of market economy.