SUMMARY


This work is presented according with the modality of thesis base on 
summary of publications established at the Deparment of Engineering 
Projects of the Valencia University of Technology. Its consist of six 
research articles. Two of them have been published in the magazine 
“Packaging Technology and Science”, another two different research 
articles have been published in “Advances in Experimental Mechanics 
Vols 7-8”, a fith have been published in “World Congress on Engineering 
2007, Vols 1 and 2” and the sixth article have been sent and it is pending  
the magazine “Packaging Technology and Science” decision.

The common link between the research articles is investigate thoroughly in 
the generation of new knowledge inside the field of packaging engineering.  
Its final objective is to improve the current simulation techniques of the 
hazards transmitted to products and packaging in the transport and 
distribution processes.

The investigations exposed in each of the articles, attempt to give a partial 
contribution to the ambitious planned objective. One of the main  
mechanical abuse, applied to a packaged product during the transport and 
distribution processes, is the impacts which it is submitted. The first 
research article is focus on the measurement and analysis of these received 
impacts by packaged products, which are sent by air mail by means of 
distribution companies (DHL and FedEx) between Europe and USA. 
This gives the necessary data to simulate, in the laboratory, the 
intercontinental transport conditions of packages, in order to achieve a 
correct design of the protection packages.

The magnitude of the impacts usually is described as a function of its 
equivalent drop height (EDH) and the impact orientation, in order to 
facilitate the drop tests at the laboratory. Usually is used a package that 
contains an acceleration recorder, and the data obtained is processed to 
give an statistic distribution of the expected drop-height in the distribution 
process. That’s the reason why the third research article objective has been  
to obtain the most accurate EDH estimation method, which is achieved 
when it is based on the use of the total velocity change parameter during 
the impact. The methods based on the impact velocity for the EDH 
calculation should not be used due to the high error introduced in its 
estimation.

Since the cushion packages which are used as product protection in the 
transport and distribution processes, are calculate and designed taking into 
account the maximum height of the expected drop, obtained by means the 
EDH estimation; its important to estimate correctly the distribution 
environment. Due to the negative environmental impact of the materials 
used as cushion of the package products, as the expanded polystyrene, 
there is a growing interest in  one of the most renewable and available, the 
paper, as substituted. In the sixth research article have been proved that 
the cushion materials develop with precompressed  multi-layer corrugated 
paperboard is a viable alternative as protection of the products against 
repetitive impacts in opposition to polymeric materials, which are less 
respectful with the environment. This is also due to the good behaviour in 
transmitted acceleration and frequency response of the material.

Another important mechanical abuse, applied to the packaged product 
during the transport and distribution processes, is the dynamic 
compression at which the packages are submitted. The objective of the  
fourth research article has been focused on obtaining a method which 
allows to assess the corrugated paperboard package ability to support 
dynamic compression loads in long time. Nowadays it has not been 
established a method by means the capacity of the paperboard to support 
dynamic compression loads in long time periods can be measured. 
Nevertheless, it has been demonstrated that the accumulated damage in 
corrugated paperboard, which are submitted continuously to random 
dynamic compression loads, can be obtained through the evaluation of the 
system modal parameters extracted from its frequency response function. 

The second research article has been focused on the analysis of the 
vibration levels which are transmitted to the loads in the road 
transportation. The vibrations produced by vehicles depend on variables 
as the load level used in the loading platform, the type of pneumatic or 
mechanic suspension of the vehicle platform and the velocity developed 
by the vehicle at that moment; as has been demonstrated in the PSD 
functions obtained in the second research article of the present thesis, 
after the data analysis of Spanish roads vibration records.

In the present thesis has been demonstrated that is possible to obtain a 
PSD function which shape depends exclusively on the transportation ways 
and which energy level depends on the velocity developed by the vehicle. 
The principal limitation of assuming a random vibration process as 
Gaussian-distributed and stationary when it is simulated is due to the used 
of a PSD function as a sole descriptor of the road vehicle vibrations. This 
limitation is resolved by the application of a new simulation technique that 
reproduce the amplitude changes of the process if the root mean square 
statistical distribution (RMS) of the vibration signal is known. That’s the 
reason why the fifth research article has been focused on  obtaining a new 
statistical model which describes with more accuracy the statistic 
distribution of the random vibrations generated by road vehicles, and 
which allows at the same time develop simulation tests in the laboratory,  
that includes the generation of random vibrations of different energy 
levels. The new developed model describes with more accuracy the 
statistical character of the random vibrations generated by road vehicles 
than the Weibull three parameters model.