In order to protect the goods from being damaged in the process of circulation, they are not damaged due to impact and vibration. The packaging used is called cushion and vibration-proof packaging, also called buffer packaging. With the development of economy, the products are trans-provincial and cross-border transportation has increased. The buffer packaging of products has received more and more attention. The rational design of the packaging structure will minimize the loss of goods during transportation, loading, unloading and storage. This is the significance of buffer packaging.

Development of buffer packaging design theory

During World War II, transported by various military supplies, especially high-precision electronic equipment, Mindlin and his team at Bell Labs applied the vibration analysis theory in the mechanical field to the past. By relying on the “testing method” or in the packaging field of analysis and design based on experience, a unique “buffer packing theory” has been formed. In 1968, Newton proposed the theory of boundary conditions for the failure of packaging products, established a brittleness assessment theorem and its testing methods, and was incorporated into the American Materials Testing Standard (ASTM). Mindlin and Newton’s pioneering work laid the foundation for the analysis and design of modern cushioning packaging.

In the 1980s, based on the theory of brittle-valued boundary conditions, U.S. MTS Systems Co., Ltd. and the School of Packaging at Michigan State University jointly developed a step-by-step design method for buffer packaging, and later developed a more complete buffer packaging design. Six-step method: determine environmental conditions of circulation; estimate product fragility; product redesign; calculation of gasket material; design packaging system; test packaging system prototype, and give ASTM standards to be implemented in each step, so as to make buffer packaging The design theory has made rapid progress.

Over the past decade or so, scholars from various countries, including Chinese packaging and scientific and technological workers, have paid great attention to and actively participated in the exchange and development of buffer packaging design theory, which has greatly facilitated the development of computer-aided design techniques such as buffer packaging and various types of linear and nonlinear buffer packaging. System impact and vibration response analysis, buffer packaging system analysis and design model, buffer packaging probabilistic design method and other fields have achieved a series of important results. In short, more than 40 years since the publication of Mindlin's paper, the research on cushioned packaging design theory has made great progress. The research on the mechanical properties of cushioning materials, assessment of product fragility, dynamic models, and design methods is increasingly practical and accurate. The design practice of buffer packaging is also increasingly reasonable. The main results are reflected in the following aspects:

Established the theory of product cushioning and vibration isolation;
Measured the maximum acceleration value that a large number of products can withstand without physical damage or functional failure, that is, product fragility;
All major industrial countries have successively carried out investigations and tests of the circulation environment and have achieved great results, laying a solid foundation for the packaging and transport testing of products;

Developed a lot of advanced packaging testing equipment, and the computer used in packaging test data processing and buffer anti-vibration packaging design;
Many countries (including China) have formulated a variety of packaging standards concerning cushioning and anti-vibration.

Problems with Buffered Packaging Design Theory

Although the research on buffer packaging technology has made great progress, there are still a lot of problems in buffer packaging design theory and methods that need further study and exploration, mainly reflected in the following aspects:

The method proposed by the proposed damage boundary to characterize the vulnerability of an item is based on the theoretical basis of considering the package as a single-degree-of-freedom linear packaging system. However, actual products, especially sophisticated electronic instruments, have multiple fragile components. Different impact frequencies and waveforms have different impact amplification ratios for the product, and different responses of the products form different incentives and impact amplification ratios for the fragile components of the product. Therefore, the method of evaluation of brittleness, which is an important basis for buffer packaging design, has yet to be developed. However, no more authoritative and reasonable experimental theories and methods have been published yet.

In packaging engineering, handling problems in a single degree of freedom, in addition to its practicality and simplicity. It is also very important to study the basic laws of packaging dynamics. But in theory, any product can be considered as having infinite degrees of freedom. Even considering only a limited number of fragile components, many items must be packaged with “one or more degrees of freedom” in order to provide a reasonable package design. The basic situation is "species: one is that the contents of the package itself is a multi-degree-of-freedom system, such as certain instruments and equipment, and their mass, elastic elements, and damping elements are the same in size and distribution as the buffer packaging system, if forced to simplify Single degree-of-freedom systems can cause large errors; the other type is subpackaging in large packages, such as the use of container transportation. However, the current domestic and foreign standards have not included the issue of multi-degree-of-freedom packaging.

In the packaging design process, because of too much emphasis on buffering and neglected anti-vibration packaging. The fourth step of “Cushioning Material Calculation” of the six-step process for buffer packaging design mentioned above should consider the issue of coordination between impact and vibration. However, only the buffer design part has standards for reference, and the vibration-proof packaging part does not. Any standard can be used. The investigation and analysis of many actual product damage cases show that with the development of commodity transportation equipment and loading and unloading technologies, the impact is often not the main cause of product damage, and the damage is often caused by vibration. However, there is insufficient research on anti-vibration packaging technology, or buffering and anti-vibration are not well designed. The main disadvantages are: First, after the buffer design, only the calibration packaging system will not be resonant, or just use the vibration isolation principle for passive vibration isolation design; Second, use the impact brittle value as a time to go beyond damage. Design, but in fact many components are damaged under repeated load conditions. In view of the above, the shockproof packaging design still needs further in-depth research.

The five-step method or the six-step method of the above-mentioned buffer packaging design is in the category of “value design method”. When the buffer package satisfies the design conditions, the fixed value design method considers the packaged product to be absolutely safe, otherwise it is considered absolutely insecure. In fact, the design parameters such as circulating environmental conditions, cushioning material properties, cushion cushion geometry, and product crispness all have features that vary randomly, and contain a large amount of subjective and objective uncertainties, making it difficult to accurately characterize the suitability of a product cushioned package. Therefore, the protective ability of cushioned packaging products should be described with probability. I believe that the establishment of a buffer packaging probabilistic design method is very appropriate and necessary.

The development direction of buffer packaging design theory

Computer-aided cushioning package design and analysis

At present, in the buffer packaging design process of the product, the buffer material selection and the size calculation must not only look for many diagrams and Tables, but also require a lot of time to calculate, analyze, compare, and ultimately select a reasonable buffer packaging scheme. This traditional manual design method restricts the development of cushioned packaging design to a certain extent due to the deficiencies of its complicated process, difficult choice of programs, and a large degree of reliance on the designer's own experience. Computer simulation and information technology quickly penetrated into the field of packaging design, making computer-aided buffer packaging design and analysis possible. The introduction of computers into the design and development of products enables people to liberate them from previously complex manual designs, significantly shortening the product development cycle, and the calculation results are accurate and reliable. Therefore, major industrial countries have invested a lot of manpower and material resources to develop various intelligent packaging systems. Computer aided design technology will surely have a broader application prospect in the field of buffer packaging.

Cushion packaging design based on system analysis

From the point of view of the system, buffer packaging is a systematic project, and the buffer packaging system should be developed in the order of system operation and evaluation performed by the system analysis system design system. However, in the development process of the previous buffer packaging system, because the developers pay more attention to the design of the packaging system itself, the importance of other stages, especially the system analysis stage, is ignored, resulting in unreasonable packaging design. The waste of resources is great. In order to minimize the waste of resources in the development process of the buffer packaging system and strive to develop an optimal packaging system, the buffer packaging system must be developed according to the laws of system engineering so that it has the best protection and economy. Social adaptability and ecological characteristics are both the overall goal of the buffer packaging system and the development direction of the buffer packaging design theory.

Introducing Reliability Theory to Study Design Problems of Cushion Packaging

As mentioned above, the design of cushioned packaging is affected by many factors with random variation characteristics such as circulation environmental conditions, cushioning material properties, cushion cushion geometry, and product fragility, and it is difficult to accurately characterize the suitability of the product cushion packaging. Because the reliability theory and method can reflect objectively and accurately the influence of the external incentives and structural performance characteristics on the design structure, it is very appropriate and necessary to introduce the reliability concept to study the buffer packaging design affected by a large number of uncertainties. . That is, consider the failure probability or reliability index of the packaged product to characterize the ability of the buffer package to protect the product and the suitability of the buffer package.