# Determination of Reliability of Selected Case
## 1 Introduction
The basic idea of ITER is the analysis of the properties of simultaneous random variables, one of which quantifies the ability of the furniture structure (load-carrying capacity, strength) and the other the operating mode during the lifetime. In the system of the interference theory of reliability, strength and stress working on it are taken into consideration for evaluation of its reliability. By models here we mean mathematical models, in particular probabilistic models. The mathematical models used in reliability theory can be broadly divided into three groups: time-dependent models, stress-strength (S-S) models or interference models, and time-dependent S-S models. For time-dependent models, stress is not taken into consideration, whereas for S-S models time is not considered; but, it does not mean that the other factor is not present; it is simply neglected, or its effect is negligible. In time-dependent models, both time and stress are taken into consideration. In the work [12], these two quantities are dynamized, that is, the dependence on time is expressed. The reliability of the furniture construction can also be expressed through its safety. By the term safety, we understand the property of the product not to endanger human health or the environment, when performing the specified function during the specified time and under the specified conditions. In the narrower sense of the word, it expresses sufficient strength and stiffness of the construction. In practice, the term safety also has a wider meaning and is intertwined with the definition of reliability. For furniture construction, it is also connected with the length of the failure-free service life of the products, which means the durability of the furniture. The reliability of furniture can be achieved by its appropriate dimensioning, by using one of the methods of construction mechanics. The most appropriate is the method of limit states, where the basic reliability criterion is the achievement of a decisive limit state. A limit state is considered to be a state in which the furniture construction loses the necessary properties to fulfil its purpose safely and satisfactorily according to operational requirements. The method of limit states is the method of extreme values. It belongs to semi-probabilistic methods because it also uses deterministic approaches. In the subject literature, there are works investigating the safety and durability issues of case-type furniture in the context of the strength and stiffness of its construction [13; 14]. The work [15] investigated corner joints made of 18 mm MDF and three-layer particleboard, while the work [16] studied corner joints made of OSB. In the study [17], L-shape furniture joints produced from OSB material of different densities (OSB-I, OSB-II, OSB-III) were investigated. Additionally, single-stable joints produced from those materials were studied [18]. There are also works dedicated to the broadly understood subject of the durability of the entire structure of case furniture, for example, the durability of case furniture from the point of view of the size of the load and the number of joints [19], as well as durability of the case furniture subassembly [20]. The work [21] investigated the durability of kitchen furniture when a change in heat and humidity occurs. However, there are only a few works dedicated to the topic of the reliability of the entire structure of case furniture. The reliability of case furniture in the context of the distribution of the strains and strength of the furniture joints, having an impact on the reliability of the whole furniture construction, is investigated in the study [22]. In the study [23], the kitchen cabinets were investigated in terms of maximum load-carrying capacity. The cabinets were manufactured on a scale of 1:1 and loaded until failure happened. As indicated earlier, the durability of the furniture is recognized among the most important factors influencing the decision on buying furniture.